Designing of Solar Submersible Water Pump

Designing of Solar Submersible Water Pump

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1. INTRODUCTION The purpose of this project is to provide water to farmers and landowners with information on planning and installing solar-powered water pumping systems. Because every location has different needs and resources, this project provides the general principles required to make an informed decision on whether or not a solar pump is right for your operation.

Currently, solar water pumps are used in the western United States as well as in many other countries like India China or other regions with abundant sunlight. Solar pumps have proven to be a cost effective and dependable method for providing water in situations where water resources are spread over long distances, power lines are few or non-existent, and fuel and maintenance costs are considerable. Historically, solar water pumps have not been widely used in New York State, in part due to the perception that solar does not work in New York. However, demonstration units that have been operating over the past few years have proven that solar pumps work at capacity when needed most: during warm, sunny days. This is particularly important for animal grazing operations.

While there are several possible methods for supplying water to remote pastures, such as wind, gas/diesel pumps, and ram pumps, solar-powered water pumps may offer the best option in terms of long-term cost and reduced labor. In the relatively rare instances with favorable topography and spring or pond location, ram pumps or gravity feed may be better options. In flat areas where the water is supplied by a remote well and where there is limited access to the power grid, solar pumps appear to be the best option.

Solar pumps offer a clean and simple alternative to fuel-burning engines and generators for domestic water, livestock and irrigation. They are most effective during dry and sunny seasons. They require no fuel deliveries, and very little maintenance. Solar pumps are powered by photovoltaic (solar electric) panels and the flow rate is determined by the intensity of the sunlight.

Solar panels have no moving parts, and most have a warranty of at least 20 years. Most solar pumps operate without the use of storage batteries. A water tank provides a simple, economical means of storage. Solar pumps must be optimally selected for the task at hand, in order to minimize the power required, and thus the cost of the system. A wide variety of solar pumps is available, to meet a wide variety of needs.


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2. Solar-Powered Water Pumping System Configurations There are two basic types of solar-powered water pumping systems, battery-coupled and direct-coupled. A variety of factors must be considered in determining the optimum system for a particular application. 2.1 Battery-Coupled Solar Pumping Systems Battery-coupled water pumping systems consist of photovoltaic (PV) panels, charge control regulator, batteries, pump controller, pressure switch and tank and DC water pump (Figure 2.1.1 ). The electric current produced by PV panels during daylight hours charges the batteries, and the batteries in turn supply power to the pump anytime water is needed. The use of batteries spreads the pumping over a longer period of time by providing a steady operating voltage to the DC motor of the pump. Thus, during the night and low light periods, the system can still deliver a constant source of water for livestock.

2.1.1System Components

Pump Controller: The primary function of a pump controller in a battery-coupled pumping system is to boostthe voltage of the battery bank to match the desired input voltage of the pump. Without a pump controller, the PV panels’ operating voltage is dictated by the battery bank and is reduced from levels which are achieved by operating the pump directly off the solar panels. For example, under load, two PV panels wired in series produce between 30 to 34 volts, while two fully charged batteries wired in series produce just over 26 volts. A pump with an optimum operating voltage of 30 volts would pump more water tied directly to the PV panels than if connected to the batteries. In the case of this particular pump, a pump controller with a 24-volt input would step the voltage up to 30 volts, which would increase the amount of water pumped by the system.

Figure 2.1.1 Battery-coupled solar water pumping system.


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Charge Control Regulators: Solar panels that are wired directly to a set of batteries can produce voltage levels sufficient enough to overcharge the batteries. A charge control regulator should be installed between the PV panels and the batteries to prevent excessive charging. Charge controllers allow the full current produced by the PV panels to flow into the batteries until they are nearly fully charged. The charge controller then lowers the current, which trickle charges the battery until fully charged. The regulator installed should be rated at the appropriate system voltage (i.e., 12-volt, 24-volt, etc.) and the maximum number of amperes the solar panels can produce. The regulator should be installed near the batteries, in accordance with the manufacturer’s instructions. This usually requires only four connections: the PV panel “POS” and “NEG” terminals and the battery “POS” and “NEG” terminals. In addition to overcharging protection, a low-voltage or battery state-of-charge control is required to prevent deep-discharge damage to batteries. The low-voltage relay acts as an automatic switch to disconnect the pump before the battery voltage gets too low. The relay is activated and switches when battery voltage drops to “low-voltage” threshold, and de-activates and switches back when the battery voltage rises to “reconnect” threshold. Most suppliers of PV equipment offer a charge control regulator that combines both overcharge protection and low-voltage disconnect to protect the batteries.

Batteries: The most common batteries used in stand-alone PV systems are lead-acid batteries. The familiar deep-cycle, marine-grade battery is a good example. They are rechargeable, easily maintained, relatively inexpensive, available in a variety of sizes and most will withstand daily discharges of up to 80 percent of their rated capacity. A new type of lead-acid battery “gel cell” uses an additive that turns the electrolyte into a non-spoilable gel. These batteries can be mounted sideways or even upside down if needed because they are sealed. Another type of battery using nickel cadmium (NiCd) plates can be used in PV systems. Their initial cost is much higher than lead-acid batteries, but for some applications the life-cycle cost may be lower. Some advantages of NiCd batteries include their long-life expectancy, low maintenance requirements and their ability to withstand extreme conditions. Also, the NiCd battery is more tolerant to complete discharge. It is important to choose a quality battery rated at a minimum of 100 amp-hour storage capacity. Shallow-cycle (car batteries) should not be used for PV applications.

These batteries are lighter, less expensive and are designed to produce high-current cold-cranking amps for a short period. The battery is then quickly recharged. Generally, shallow-cycle batteries should not be discharged more than 25 percent of the rated battery capacity. Battery banks are often used in PV systems. These banks are set up by connecting individual batteries in series or parallel to get the desired operating voltage or current. The voltage achieved in a series connection is the sum of the voltages of all the batteries, while the current (amps) achieved in series-connected batteries is equal to that of the smallest battery. For example, two 12-volt batteries connected in series produce the equivalent voltage of a 24-volt battery with the same amount of current (amps) output as a single battery. When wiring batteries in parallel, the current (amps) is the sum of the currents (amps) from all the batteries and the voltage remains the same as that of a single battery.

Batteries must be protected from the elements. Batteries should be buried below the frost line in a watertight enclosure or placed in a building where the temperature will remain above freezing. If the batteries are buried, select a well-drained location. Batteries should never be set directly on concrete surfaces, as self discharge will increase, especially if the concrete surface gets damp.


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2.1.2Why we don’t Recommend Batteries in Water Pumping Systems While batteries may seem like a good idea, they have a number of disadvantages in pumping systems. They reduce the efficiency of the overall system. The solar modules operating voltage is dictated by the battery bank and is reduced substantially from levels which are achieved by operating the pump directly. Batteries also require additional maintenance and under and over-charge protection circuitry which adds to the cost and complexity of a given system. For these reasons, only about five percent of solar pumping systems employ a battery bank.. This reduced efficiency can be minimized with the use of an appropriate pump controller that boosts the battery voltage supplied to the pump.

2.2 Direct-Coupled Solar Pumping System In direct-coupled pumping systems, electricity from the PV modules is sent directly to the pump, which in turn pumps water through a pipe to where it is needed (Figure 3). This system is designed to pump water only during the day. The amount of water pumped is totally dependent on the amount of sunlight hitting the PV panels and the type of pump. Because the intensity of the sun and the angle at which it strikes the PV panel changes throughout the day, the amount of water pumped by this system also changes throughout the day. For instance, during optimum sunlight periods (late morning to late afternoon on bright sunny days) the pump operates at or near 100 percent efficiency with maximum water flow. However, during early morning and late afternoon, pump efficiency may drop by as much as 25 percent or more under these low-light conditions. During cloudy days, pump efficiency will drop off even more. To compensate for these variable flow rates, a good match between the pump and PV module(s) is necessary to achieve efficient operation of the system. Direct-coupled pumping systems are sized to store extra water on sunny days so it is available on cloudy days and at night. Water can be stored in a larger-than-needed watering tank or in a separate storage tank and then gravity-fed to smaller watering tanks. Water-storage capacity is important in this pumping system. Two to five days’ storage may be required, depending on climate and pattern of water usage. Storing water in tanks has its drawbacks. Considerable evaporation losses can occur if the water is stored in open tanks, while closed tanks big enough to store several days water supply can be expensive. Also, water in the storage tank may freeze during cold weather. 2.2.1 System Component

Power Controllers: The efficiency of a direct-coupled water pumping system is sensitive to the match between the pump and the PV system. PV panels produce a fairly constant voltage as the light intensity changes throughout the day; however, amperage changes dramatically with light intensity. During low-light levels, such as early morning and late evening, the PV array may be producing 30 volts at 1 amp.

Fig. 2.1.2.1 solar battery


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The pump motor needs current to start; however, it can run on a lower voltage. A pump controller’s circuitry trades voltage for current, which allows the pump to start and run at reduced output in weak-sunlight periods. Matching pump motor performance to the available sunlight with a properly sized controller can increase the amount of water pumped in a day by 10 to 15 percent.

Figure 2.2.1. Direct-coupled solar pumping system.


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3. DESIGNING A SOALR PUMPING SYSTEM There are many aspects of designing a solar pumping system. This guide provides the information to correctly select a pump, controller, sensors, solar array, wiring, and pipe. The process is broken down into the following steps: STEP-3.1 Suitability of the Site for Solar STEP-3.2 Determine Water Source STEP-3. 3 Determining your basic amount of water required per day. STEP-3. 4 Calculating the TOTAL DYNAMIC HEAD. STEP- 3. 5 Selecting the pump, controller and solar array. STEP-3. 6 Determining the solar resource for your location. STEP-3.7 Selecting the correct solar array mounting method. STEP-3. 8 Selecting the right size pump cable and pipe. STEP-3. 9 Using water level sensors and pump controls. 3.1 Suitability of the Site for Solar The site of the water source must then be evaluated for suitability for the installation of the solar-powered water pumping system. The following are specific issues that must be addressed:

The solar panels require a south facing location with no significant shading; Locations must be found for the water pump (surface), controllers, storage tank and other

system components; The solar array should be as close to the pump as possible to minimize wire size and

installation cost. If batteries are to be used, they must be in a reasonably dry/temperature controlled location

with proper venting; and If year-round water is required, freeze proofing issues must be addressed. A heated area is

preferred for water storage and pressure tanks. It is not economical to use PV to run a resistance heater in the winter.

Assuming that you can place the array in a location that can receive full sun, you then need to estimate the regional solar potential using published data or maps for your region4. These sources will tell you what full sun hours per day your area receives. The average for most of New York State is 2.5 hours in the winter, 5.5 hours in the summer, and 4 hours for the year. Multiply the array wattage by this number to get a rough estimate of daily power available at the site.

Figure 3.1.1 Suitable Site


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3.2 Determine Water Source The configuration of the watering system will be defined largely by the type of water source and its location relative to the places you want to provide water. The water source will either be subsurface (well) or surface (pond, stream, or spring). Wells are preferable because of the improved water quality and consistency. However, wells are expensive to drill, particularly where water tables are deep. Surface water sources may vary seasonably, such that the amount and quality of the water is low during the summer when it is needed most. For wells, the following need to be determined:

Static water level; Seasonal depth variations; Recovery rate; and Water quality.

The well driller should give you this information for a new well. For most wells, water quality is not an issue if not used for human consumption. For surface water sources, the following need to be determined:

Seasonal variations; and Water quality, including presence of silt, organic debris, etc.

The water delivery system should be mapped out to determine the location of the water source and the desired points of distribution. The map should have height contours so that you can calculate the height differences. Figure 7 shows an example of a farm that can use a low lying pond as the source combined with a storage tank placed on a hill. The water can then be gravity fed through the distribution pipes to individual paddocks. A water resource manager can assist you with planning a water distribution system.


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3.3 Daily Water Requirement and Storage The size and cost of your system will depend on the amount of water required per day. AC pumping systems connected to a utility power grid are generally designed to run on demand with a specified flow rate. Unlike grid-tied systems, solar pumping systems are designed to provide a certain quantity of water per day. Water is pumped during sunlight hours and stored in a tank. The daily requirement is simply a total of all water required during a 24 hour period. This quantity is expressed in LITERS PER DAY or GALLONS PER DAY.

Tanks are used to store water for use during the night or periods of cloudy weather. Tanks are usually large enough to hold 3 to 5 days of daily water output.

TABLE 3.3.1 TYPICAL WATER REQUIREMENTS FOR SMALL APARTMENT OF

FOUR FLATES

If your application requires large amounts of water on a periodic basis, like watering a crop once a week, divide the weekly requirement by 7 to arrive at an average daily requirement. A system such as this should have a tank large enough to hold at least 1.5 times the weekly requirement.

Information about water needs is available from many sources. Government agencies can provide information for household and agricultural applications. Some guidelines for water uses and daily quantities are shown below. These are general guidelines only; actual values depend on many factors.

Use for each flate Usage in liters per day Each person 500*4=2000 Cleaning of house and car 200 Cooking and other usage 300 Total 2500*4=10000


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3.4 Calculating TOTAL DYNAMIC HEAD Total Dynamic Head, or TDH, is a very important factor in system design. TDH is the effective pressure the pump must operate against. TDH is expressed in METERS or FEET. TDH is the sum of 3 factors:

TOTAL VERTICAL LIFT TOTAL VERTICAL LIFT is the sum of the STANDING WATER LEVEL, DRAWDOWN and ELEVATION. The STANDING WATER LEVEL (SWL), measured in meters or feet, is the distance from the top of the well to the surface of the water in the well when no water is being pumped. The STANDING WATER LEVEL water is also called the "static" (at rest) water level. The DRAWDOWN, measured in meters or feet, is the distance the standing water level lowers when water is pumped from the well. Depending on the well, the DRAWDOWN may be 1 to 20 meters (3 to 50 feet) or more. Slow flowing wells will have the greatest DRAWDOWN. The STANDING WATER LEVEL and DRAWDOWN can also be provided by the well drilling company or by testing the well. The DRAWDOWN is related to the flow rate of the pumping system; the greater the flow rate, the greater the DRAWDOWN. NOTE: The sum of the STANDING WATER LEVEL and the DRAWDOWN is called the PUMPING LEVEL. ELEVATION to point of use, measured in meters or feet, is the vertical distance from the top of well to the point of use, such as the top of a storage tank.

FRICTION LOSS The FRICTION LOSS, measured in equivalent meters or feet, is the pressure required to overcome friction in the pipes from the pump to the point of use. The friction is based on: rate of flow, the length, diameter, and type of pipe, and also the number and type of pipe fittings used. The greater the flow, the greater the FRICTION LOSS. Tables are used to calculate friction loss.

TANK PRESSURE TANK PRESSURE, expressed in equivalent meters or feet of head, is the operating pressure of the storage tank. Solar pumping systems have very large tanks because no water is pumped at night or in very cloudy weather, pressurized tanks are rarely used in solar pumping systems. However, systems with battery power can be used to pump to pressurized tanks. For typical, nonpressurized systems, TANK PRESSURE equals zero. TOTAL DYNAMIC HEAD = TOTAL VERTICAL LIFT + FRICTION LOSS + TANK PRESSURE 3.4.1 TOTAL VERTICAL LIFT To calculate TOTAL DYNAMIC HEAD it is best to make a sketch like Figure on next page. Calculate the TOTAL VERTICAL LIFT by adding the STANDING WATER LEVEL, the DRAWDOWN and the ELEVATION. 3.4.2 FRICTION LOSS In most cases, calculating FRICTION LOSS can be simplified. If the system storage tank is located close to the well head, 10 meters (30 feet) or less, and the recommended pipe size is used, a simple rule can be used. Friction loss, in equivalent head, can be estimated at 5% of the TOTAL VERTICAL LIFT. This will allow for a few straight runs of pipe and a few fittings.


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In cases where the tank is located far from the well, more than 10 meters (30 feet),more accurate calculations must be used for FRICTION LOSS. FRICTION LOSS is based on the size and length of the pipe, the number and type of fittings, and the FLOW RATE. Solar pumping systems, unless connected to a battery, pump only when the sun is shining on the solar array.

Cloudy weather will also affect the flow rate. The flow rate varies over the course of the day with the peak flow occurring at midday. Because our system design is not complete (a pump and array have not been selected yet), the TOTAL DAILY OUTPUT can only be estimated. To estimate the flow rate, make a guess for the TOTAL DAILY OUTPUT and use the following equations: US: GPM (gallons per minute) = GPD (gallons per day) / 360 Metric: LPM (liters per minute) = LPD (liters per day) / 360 Example: DAILY REQUIREMENT = 10000 liters per day FLOW RATE = 10000 / 360 =28 liters per minute Calculate the friction loss by adding the length of all piping in the system. Use TABLE 2 or 3 to express the friction loss from fittings in equivalent length of pipe. Add the total of fitting losses to pipe losses. Using the total equivalent length of pipe, and the flow rate, find the head loss in meters per meter of pipe, or feet per foot of pipe, from TABLE 4 or 5. Multiply this number by the total equivalent length of pipe. This number is the FRICTION LOSS in meters or feet of head.

When the system design is complete, use the actual DAILY OUTPUT of the chosen pump and array, recalculate the FLOW RATE, and review the FRICTION LOSS calculations. If necessary, recalculate the FRICTION LOSS and the TOTAL DYNAMIC HEAD and double-check your pump and array choice. 3.4.3 TANK PRESSURE Tank pressure is specified from other system needs. When a pressurized tank is used, convert the cutoff pressure to meters or feet of head. If the water is allowed to flow free into an open or vented tank, the TANK PRESSURE is zero, use a value of zero when calculating TOTAL DYNAMIC HEAD. To convert pressure to equivalent head, use the following formulas: US: HEAD (in feet) = PRESSURE (psi) x 2.31 Metric: HEAD (in meters) = PRESSURE (kPa) x 0.102


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3.4.4 Calculations for TOTAL DYNAMIC HEAD 3.4.4.1 CALCULATING TOTAL VERTICAL LIFT: Standing water level LINE 1 _____70________ Drawdown LINE 2 _____10________ Elevation LINE 3 _____20________ TOTAL VERTICAL LIFT (add lines 1 – 3) LINE 4 _____100________

FIGURE 3.4.4.1 TOTAL DYNAMIC HEAD


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3.4.4.2 CALCULATING FRICTION LOSS: Simplified method, tank close to well (see text): FRICTION LOSS (multiply line 4 by 0.05) LINE 5 ______5_______ Calculated method, tank far from well (see text): Total length of all pipes; add the length of all pipes. ____70____ + _____10___ + ____20___+____10____ =110 LINE 6 _____110______ Equivalent length of fittings; add the equivalent Length of all fittings (from TABLE 2 or 3). _____2___ + ____2____ + ____2____ = 6 LINE 7 ______6_______ Total equivalent length of pipe (add lines 6 & 7) LINE 8 _______116______ TOTAL DAILY OUTPUT (estimated or actual) LINE 9 ______10000_______ Flow rate (divide line 9 by 360) LINE 10 ______28_______ Friction loss per length (from TABLE 4 or 5; use next largest flow rate and actual pipe size) LINE 11 ______0.14_______ FRICTION LOSS (multiply line 8 & 11) LINE 12 ______116*0.14=16.24_______ 3.4.4.3 CALCULATING TOTAL DYNAMIC HEAD: TOTAL VERTICAL LIFT (Enter line 4) LINE 13 _____100________ TOTAL FRICTION LOSS (Enter line 5 or 12, see text) LINE 14 ______16.24_______ TANK PRESSURE (in meters or feet of head) LINE 15 ______0_______ TOTAL DYNAMIC HEAD (add lines 13 – 15) LINE 16 ______99.76______


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3.4.4.4 CALCULATING VELOCITY OF FLUID IN PIPE V=Q/A Where Q= flow rate in m3/sec A=area in m2 V=28*0.001*4/3.14*60*(.0158)2 V=2.38 m/s NOTE: Velocity of fluid is less then 3m/s so we can take ½” pipe

Tables Table 3.4.4.1 (metric) FRICITON LOSS FOR FITTINGS IN EQUIVALENT OF PIPE

Nominal size of pipe fitting(npt) ½” ¾” 1” 1 ¼” 1 ¼” 2”

Types of fitting and application Equivalent length of pipe(in meters) Insert coupling

0.9 0.9 0.9 0.9 0.9 0.9

Threaded adapter(plastic to thread)0.6

0.9 0.9 0.9 0.9 0.9 0.9

90 standard elbow

0.6 0.6 0.9 1.2. 1.2 1.5

Stanadard tee (straight flow)

0.3 0.6 0.6 0.9 0.9 1.2

Standard tee (90 flow)

1.2 1.5 1.8 2.1. 2.4 3.3

Gate valve 0.3 0.3 0.3 0.3 0.6 0.6 Swing check valve

1.5 2.1 2.7 3.7 4.0 5.2

TABLE 3.4.4.2 (US) FRICITON LOSS FOR FITTINGS IN EQUIVALENT OF PIPE

Nominal size of pipe fitting(npt) ½” ¾” 1” 1 ¼” 1 ¼” 2”

Types of fitting and application Equivalent length of pipe(in meters) Insert coupling

3 3 3 3 3 3

Threaded adapter(plastic to thread)

3 3 3 3 3 3


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90 standard elbow

2 2 3 3 4 5

Stanadard tee (straight flow)

1 2 2 3 3 4

Standard tee (90 flow)

4 5 6 7 8 11

Gate valve 1 1 1 1 2 2 Swing check valve

5 7 9 12 13 17

TABLE 3.4.4.3 (METRIC)FRICTION LOSS SCH 40 PVC PIPE IN EQIVALENT METERS

NOMINAL PIPE SIZE LOSS IN METERS OF HEAD PER ONE METER OF PIPE

FLOW IN LITER PER MINUTE

½” ¾” 1” 1 ¼” 1 ¼” 2”

5 10 15

0.0058 0.021 0.044

0.0053 0.011

20 25 30

0.076 0.11 0.16

0.019 0.029 0.041

0.0057 0.0086 0.012

35 40 45

0.21 0.054 0.069 0.086

0.016 0.021 0.026

0.0055 0.0069

50 60 70

0.1 0.14 0.19

0.031 0.043 0.058

0.0084 0.012 0.016

0.0072

80 90 100

0.074 0.092 0.011

0.020 0.025 0.030

0.0093 0.012 0.014

0.0047 125 150 175

0.17 0.046 0.064 0.085

0.21 0.30 0.40

0.0071 0.013 0.13

200 225 250

0.11 0.14 0.17

0.51 0.64 0.77

0.17 0.21 0.26


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TABLE 3.4.4.4 (US)FRICTION LOSS SCH 40 PVC PIPE IN EQIVALENT FEET NOMINAL PIPE SIZE LOSS IN FEETS OF HEAD PER ONE FOOT OF PIPEFLOW IN

LITER PER MINUTE

½”

¾” 1” 1 ¼” 1 ¼” 2”

2 3 4

0.041 0.087 0.148

0.022 0.037

5 6 7

0.222 0.312 0.415

0.057 0.08 0.106

0.018 0.025 0.033

8 9 10

0.53 0.66 0.805

0.135 0.168 0.204

0.042 0.052 0.063

0.017

12 14 16

0.286 0.38 0.486

0.089 0.118 0.151

0.023 0.031 0.04

0.014 0.019

20 25 30

0.605 0.228 0.387

0.028 0.043 0.06

0.028 0.043 0.06

0.013 0.018

35 40 45

0.169 0.216 0.28

0.08 0.102 0.125

0.024 0.03 0.038

50 60 70

0.154 0.216 0.287

0.046 0.064 0.085


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3.5-Selecting the Pump, Array and Controller Selecting the right components is crucial to performance of your system. Component selection requires three pieces of information; the DAILY WATER REQUIREMENT, the TOTAL DYNAMIC HEAD, and the SUN HOURS ON TILT. Follow the steps below to choose the correct pump, array, and controller for your application. 3.5.1 CHOOSING PUMP TYPE 400 series pumps are low volume pumps that allow for a simple low cost system. These pumps are typically used for single family water supply and livestock watering. 400 series pumps offer much higher volumes of water, and will pump from greater depth, but require larger, more costly, solar arrays. These pumps are usually used for village water supply and moderate agricultural needs. If you are unsure about which type of pump to use, consider using a 400 series first. This will be the lowest cost option. If the 400 series does not provide enough water, select a 400 series system.

Both 400 and 400 series pumps will deliver more water per day when the solar modules are placed on a TRACKER. TRACKERS boost water output in the morning and afternoon and extend the daily run time by gathering more sunlight. Trackers will boost output 30-40% in summer and about 5-15% in winter. Keep this in mind when sizing your system. Trackers have certain drawbacks and cannot be used in all situations

DETAILS OF V4 MOTORS & PUMPS 3.5.1.1 4 " Submersible Motors 4” VARUNA motors are excellence in engineering & high efficiency electrical design ensures maintenance free long life in most critical applications and are available in single and three phase models. Technical Specifications and Advantage

Oil Lubricated

• 4” VARUNA Oil Lubricated Motors are rewindable • Upper / Lower bracket and motor base are cast iron with nickel coating • Motor shaft is of SS 420 grade or above • Stator shell is of SS 304 • Winding wire is dual coated with insulation Class-B • Flange and shaft protrusion as per NEMA standard • Degree of protection: lP 58 • Max oil temperature: 50°C • Start/H: Max30 • Allowable voltage variation: + 6% / -10% • Max depth immersion 250m • Mounting : vertical / horizontal • Single phase motors are capacitor start capacitor run • Coolant: Die electric non toxic


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Versions

• Single Phase 0.25 kW to 2.2 kW, 220-230 Volt/50Hz • Three Phase 0.55 kW to 5.5 kW, 380-400 Volt/ 50Hz • Other voltage and frequencies are also available on demand

Water Lubricated

• 4” VARUNA Water Lubricated Motors are rewindable • Upper / Lower bracket and motor base are cast iron with nickel coating • Motor shaft is of SS 420 grade or above • Stator shell is of SS 304 • Winding wire poly propylene with insulation Class-B • Flange and shaft protrusion as per NEMA standard • Water lubricated radial and thrust bearing • Degree of protection: lP 68 • Max water temperature: 50°C • Start/H: Max 30 • Allowable voltage variation: +6%/-10% • Max depth immersion: 250m • Mounting : vertical / horizontal • Motor cable length: 3m / 3 core

Versions • Single Phase 0.25 kW to 2.2 kW, 220-230 Volt / 50Hz • Three Phase 0.55 kW to 5.5 kW, 380-400 Volt /50 Hz • Other voltage and frequencies are also available on demand


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Figure 3.5.1.1 C/S Drawing Motor


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3.5.1.2 4" Submersible Pumps Product Advantages and Specification

• VARUNA 4” multistage pumps with new hydraulic design offers high level of performance, mechanically build to last long and provide un-interrupted service.

• Suction and discharge outlets are made of Cast Iron with nickel coating. Also available in Stainless Steel on request.

• Carefully designed impeller and bowl are made of resin impregnated thermoplastic. This material ensures high performance and longer life cycle of pump.

• Pump casing in SS304. • Pump shaft in SS410. • Hex rubber bush and Stainless Steel Sleeve with hard chrome increase the wear resistance of

this pump against sand. • Efficiently designed check valve guarantees trouble free service. even in most critical

application. • Cable guard and strainer in stainless steel. • Pumps available in radial and mixed flow designs. • Pump-Motor connection according to NEMA standard. • Operating range:

Head range : 6 mtr. to 278 mtr. Flow rate : l0 lpm to 500 lpm. Immersion : 1 mtr. Minimum.

• Minimum level sand content: 50gm/m3. • Application: These pumps are for domestic, agriculture & industrial usage.


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Figure 3.5.1.2 C/S Drawing Pump

4" Submersible Pumps


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MODEL NAME RATING DISCHARGE l/min 0 23 42 55 85 100 115 120 SINGLE

PHASE THREE PHASE STAGE kW HP

m3/h 0 1.38 2.52 3.3 5.1 6 6.9 7.2

4RF-400/05 4RF-400/05 5 0.55 0.75 29 28 26 25 20 18 15 13

4RF-400/07 4RF-400/07 7 0.75 1.00 41 39 37 35 29 25 21 18

4RF-400/08 4RF-400/08 8 1.10 1.50 46 44 42 40 33 29 24 21

4RF-400/10 4RF-400/10 10 1.10 1.50 58 56 53 50 41 36 30 26

4RF-400/12 4RF-400/12 12 1.50 2.00 70 67 63 60 49 43 36 31

4RF-400/14 4RF-400/14 14 2.20 3.00 81 78 74 70 57 50 42 36

4RF-400/16 4RF-400/16 16 2.20 3.00 93 89 84 80 66 58 48 42

4RF-400/18 4RF-400/18 18 2.20 3.00 104 100 95 90 74 65 54 47

4RF-400/22 4RF-400/22 22 2.20 3.00 128 122 116 110 90 79 66 57

4RF-400/25 25 3.00 4.00 145 139 132 125 102 90 75 65

4RF-400/31 31 4.00 5.50

180 172 164 155 127 112 93 81


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Table 3.6.1.2 WO : 5L HP : 0.33 / STAGE :9 S.L. 40 mm CAP RUN : 25 mfd.

VOLT HEAD ( meter )

DIS ( lpm ) Amp Rpm

OVER ALL EFF %

230 1 55 3.94 2790 1.09 230 18 44 4.05 2775 14.01 230 22 40 3.85 2776 17.12 230 32 28 3.88 2789 17.62 230 39 20 3.88 2801 14.94 230 43 12 3.76 2803 10.67 230 46 0 3.66 2807 0.0 180 1 51 3.77 2630 1.37 180 18 39 3.82 2616 17.46 180 22 34 3.88 2635 18.96 180 32 23 3.83 2649 18.86 180 39 14 3.73 2685 13.67 180 43 0 3.81 2672 0 150 1 44 3.65 2297 1.5 150 18 27 3.64 2292 15.13 150 22 22 3.67 2289 15.37 150 32 11 3.59 2404 11.10 150 38 0 3.44 2413 0 130 1 34 3.25 2066 1.47 130 18 11 3.26 2072 8.28 130 22 7 3.27 2081 6.42 130 27 0 3.14 2181 0.00 RESISTANCE TEST : BR YB RY 15.5 24.4 39.9


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3.5.1.3 Calculatio

n of Watt Watt= Volts*Amp =230*3.85

Watt = 886W input in motor But the losses are occurred in the motor system and it must be considered as 20% So, Watt =1200W

NO LOAD TEST VOLT AMP WATT HZ 230 3.40 680 49.8 BLOCK ROTOR TEST VOLT AMP WATT HZ 150 4.10 560 49.8 VOLT CAP.VOLT VOLT S/F meter 230 393 120 20.12 180 259 110 12.08 150 185 130 153

Mini. Start. Volt

AMP WATT

105 2.50 240 Temperature Rise : 29.67°C Starting torque : 0.087 kgm Full load torque : 0.125 kgm % of torque : 70.33 Winding detail wire (SWG) Turns

Running winding 25 100

Starting winding 26 128

Stamping size : 90 X 48 mm Slot size : 24 / R - 18 Pitch (Running & Starting) : 1-8 , 1-10 , 1-12


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3.5.1.4 Calculation of Efficiency Efficiency=Head* Discharge/6120*Pin(KW) = (32*28)/(6120*1.2) Efficiency = 17.62% 3.5.2 SELECTING THE RIGHT INVERTER CONTROLLER & PUMP CONTROLER 3.5.2.1 Pump Controller

Specification For V4 oil lubricated motor • Powdered coated metal box • Voltmeter, Ameter • Magnetic Contactor • Start up with disconnecting relay • Permanent run capacitor • Start capacitor fitted • Thermal overload protractor manual reset • Connection terminal strip • Inlet outlet cable cutput • On off push button • Pilot lamp • Push to volt push button

Table 3.5.2.1 Capacitor Details Voltage /Hz HP Capacitor

running uF Capacitor Starting uF

Thermal Overload Protector rating amp

230 Volt 50 Hz

0.33 30 100-120 6-10

3.5.2.2 Inverter Controller Today’s older generation would probably remember the days of the solar powered calculator or the solar powered watch when they were in grade school. But today, the use of solar or photovoltaic energy grants the earth and its inhabitants with a cleaner and healthier future. A far cry from checking the time or calculating bills. More responsible home owners are becoming environmentally aware about the damages of fossil fuels and are turning to renewable energy options. Aside from wind or hydro-power, solar energy seems to be the most abundant and reliable as, well, the sun rises and sets every day. If one wishes to use this kind of system, it is best to get some photovoltaic training to get the fundamentals. Solar energy is composed of a system with panels, wiring and circuitry. Solar cells are installed pick up and store energy. Once the solar energy has been harnessed by the solar cells, it is time for the Photovoltaic inverter to do its job. The inverter is the heart of the whole power system and the key piece in the providing of renewable energy to the home. Energy that is generated by the solar cells is known as Direct Current or DC, which is not too useful for powering most if any household appliances due to its low voltage.


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Interval training will enumerate the inform owners of what devices use DC but it is definite not strong enough for living needs. For the DC to be compatible with the energy that comes into the home it must be converted to the form appliances and the power grid setup expects, Alternating Current or AC. This kind of current is used in national power grids because it can travel in thinner wires and does not suffer too much loss or degradation through long distances. The circuitry of the inverter is quite sophisticated but generally works as a transformer by taking in the direct current and changes its form into true sine wave alternating power. Transistors that rapidly switch on and off make direct current act or behave similar to alternating current with the end result of successfully powering up all appliances.

Inverter training on properly monitoring the current can view it on an oscilloscope that shows a true sine wave representation on a Cartesian plane with the start of the wave beginning at zero, rising to a positive point and curving down pass zero to a negative point and arching back to zero as compared to direct current which is seen as a straight line. Photovoltaic systems are not simply a plug-and-use type of gadget. One has to understand the instruments as well as power itself. Further photovoltaic training can cover reading alternating current and understanding its five characteristics of AC power: Amplitude, Cycles, Frequency, Peak-to peak and RMS or Root Means Square. This can be valuable in owning a complete photovoltaic power system at home.

Having the proper inverter and solar training allows the inverters to be grid inter-tied by hooking up to the whole utility grid. With this type of connection and access, home owners can actually help their national power suppliers by either switching to solar power while electricity demand is great or by giving clean and excess power to them. This results in the miraculous "turning back the meter" as some location practice this as a credit system that works well for both the home owner and the power companies. One can literal see the meter move backwards.

Photovoltaic inverters are suited with safety features such a breakers that can be tripped manually for the protection of linemen and electricians from being electrocuted if repairs or routine check-ups need to be done. An "anti-islanding" feature is also built in for immediate disconnection from the

Figure 3.5.2.1 Inverter


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power grid if levels get to high and hazardous for homes and halts any feeding of more power. Having a solar power system for the household is very expensive and needs a lot of planning such as purchasing and installing of the solar panels, wiring, set-ups and hook-ups.

But the long term benefit speaks for itself once it becomes fully efficient and operational. However home owners must be aware that the Photovoltaic inverter is the most important component in the whole network. Without it, power with be there but it will be useless unless converted. Even though it is one of the most costly parts, skimping should be avoided as it would be the biggest mistake one can make for it is the whole heart of the operation. Just as the Sun is the center of the solar system, so is the Photovoltaic inverter in the homes. 3.5.2.2.1 Basic functions: 1. Intelligent protection control and management on the system, in terms of low voltage, over voltage, over load, short circuit, deficiency of water in well, excess of water in tank, etc. 2. Intelligent settings of key parameters for the system in terms of input DC voltage, output current, soft start time of the pump, coefficient of solar panels and pumps, etc. 3.5.2.2.2 Features:

Wide range DC input: 176V~264V or 304~456V High efficiency: above 95% Max power point tracking (MPPT) function available Intelligent inverter control Intelligent auto-protection technology for inverter system Intelligent optimization for combination of solar panels, sunlight and pumping capacity System can select with storage batteries or without storage batteries

3.5.2.2.3 Requirement For Inverter Model: INV1440 Input Voltage-24v Input load-60amp Output Voltage -240V Output load-5.5Amp Enclosure class: IP 53 Ambient temperature: In operation: –10°C to +50°C; during storage: –20°C to +60°C Relative air humidity: 95% Marking: CE Weight: 5 kg Dimension: 200mm*240mm*430mm 3.5.3 SELECTING THE PUMP AND ARRAY – 400 ONLY 400 series pumps are small diaphragm pumps that provide for a low cost solar pumping system. They can operate with as little as 1200 Watts of power depending on TOTAL DYNAMIC HEAD and DAILY WATER REQUIREMENT. 400 series use a rubber diaphragm for pumping. The diaphragm does not tolerate water with a high sand content. The sand will cause premature diaphragm failure. Certain sands, such as shale or silica, are worse than others. 400 series pumps


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should be used with a SAND SHROUD if there is any possibility of sand in the well. SAND SHROUDS fit over the pump to prevent sand from reaching the pump intake. SAND SHROUDS increase the diameter of the pump and require a larger well casing. 400 series pumps also require yearly maintenance to replace the diaphragm and cam assembly. Failure to service the pump will lead to diaphragm failure and major damage to the pump motor and electrical parts. This may void warranties. There are 3 pumps in the 400 series. See TABLE 3.5.3.1 below for basic performance and well diameter requirements. TABLE 3.5.3.1 DIAMETER OF BORE PUMP MODEL

MAXIMUM DYNAMIC HEAD

TYPICAL DAILY OUTPUT

MINIMUM WELL DIAMETER/ NO SANDSHROUD

MINIMUM WELL DIAMETERWITH SAND SHORUD

300/9 32 METER 9000-11000 LITERS

5 INCHES 6 INCHES

If the minimum well diameter, and maximum TOTAL DYNAMIC HEAD are suitable for your system, and the daily output is close to your needs, consider a 400 series pump. This will be the lowest cost solution. Remember, a 400 pump requires yearly maintenance for proper operation. Use the following section, "SELECTING THE PUMP AND ARRAY – 400 ONLY", to select the correct array and predict performance of your system.

Select a 400 series pump using above value. The TOTAL DYNAMIC HEAD of the well must be less than or equal to the MAXIMUM TOTAL DYNAMIC HEAD of the selected pump. The diameter of the well must be greater than or equal to the MINIMUM WELL DIAMETER for the selected pump.


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3.6 Determining Your Solar Resource 3.6.1 History of solar cells The term "photovoltaic" comes from the Greek φῶς (phōs) meaning "light", and "voltaic", meaning electric, from the name of the Italian physicist Volta, after whom a unit of electro-motive force, the volt, is named. The term "photo-voltaic" has been in use in English since 1849.

The photovoltaic effect was first recognized in 1839 by French physicist A. E. Becquerel. However, it was not until 1883 that the first solar cell was built, by Charles Fritts, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions. The device was only around 1% efficient. Subsequently Russian physicist Aleksandr Stoletov built the first solar cell based on the outer photoelectric effect (discovered by Heinrich Hertz earlier in 1887). Albert Einstein explained the photoelectric effect in 1905 for which he received the Nobel prize in Physics in 1921. Russell Ohl patented the modern junction semiconductor solar cell in 1946, which was discovered while working on the series of advances that would lead to the transistor. 3.6.2 Simple Explanation

1. Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.

2. Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction.

3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.

3.6.2.1 Photogeneration of Charge Carriers When a photon hits a piece of silicon, one of three things can happen: 1. the photon can pass straight through the silicon — this (generally) happens for lower energy

photons, 2. the photon can reflect off the surface, 3. the photon can be absorbed by the silicon, if the photon energy is higher than the silicon

band gap value. This generates an electron-hole pair and sometimes heat, depending on the band structure.

When a photon is absorbed, its energy is given to an electron in the crystal lattice. Usually this electron is in the valence band, and is tightly bound in covalent bonds between neighbouring atoms, and hence unable to move far. The energy given to it by the photon "excites" it into the conduction band, where it is free to move around within the semiconductor. The covalent bond that the electron was previously a part of now has one fewer electron — this is known as a hole. The presence of a missing covalent bond allows the bonded electrons of neighbouring atoms to move into the "hole," leaving another hole behind, and in this way a hole can move through the lattice. Thus, it can be said that photons absorbed in the semiconductor create mobile electron-hole pairs.

A photon need only have greater energy than that of the band gap in order to excite an electron from the valence band into the conduction band. However, the solar frequency spectrum approximates a black body spectrum at ~6000 K, and as such, much of the solar radiation reaching the Earth is composed of photons with energies greater than the band gap of silicon.


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3.6.2.2 Charge carrier separation There are two main modes for charge carrier separation in a solar cell:

1. Drift of carriers, driven by an electrostatic field established across the device 2. Diffusion of carriers from zones of high carrier concentration to zones of low carrier

concentration (following a gradient of electrochemical potential).

In the widely used p-n junction solar cells, the dominant mode of charge carrier separation is by drift. However, in non-p-n-junction solar cells (typical of the third generation solar cell research such as dye and polymer solar cells), a general electrostatic field has been confirmed to be absent, and the dominant mode of separation is via charge carrier diffusion.

3.6.2.3 Semiconductor and p-n Junction The most commonly known solar cell is configured as a large-area p-n junction made from silicon. As a simplification, one can imagine bringing a layer of n-type silicon into direct contact with a layer of p-type silicon. In practice, p-n junctions of silicon solar cells are not made in this way, but rather by diffusing an n-type dopant into one side of a p-type wafer (or vice versa).

If a piece of p-type silicon is placed in intimate contact with a piece of n-type silicon, then a diffusion of electrons occurs from the region of high electron concentration (the n-type side of the junction) into the region of low electron concentration (p-type side of the junction). When the electrons diffuse across the p-n junction, they recombine with holes on the p-type side. The diffusion of carriers does not happen indefinitely, however, because charges build up on either side of the junction and create an electric field. The electric field creates a diode that promotes charge flow, known as drift current, that opposes and eventually balances out the diffusion of electron and holes. This region where electrons and holes have diffused across the junction is called the depletion region because it no longer contains any mobile charge carriers. It is also known as the space charge region.

Figure 3.6.2.1General layout of solar cell


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3.6.2.4 Connection to an external load Ohmic metal-semiconductor contacts are made to both the n-type and p-type sides of the solar cell, and the electrodes connected to an external load. Electrons that are created on the n-type side, or have been "collected" by the junction and swept onto the n-type side, may travel through the wire, power the load, and continue through the wire until they reach the p-type semiconductor-metal contact. Here, they recombine with a hole that was either created as an electron-hole pair on the p-type side of the solar cell, or a hole that was swept across the junction from the n-type side after being created there.

The voltage measured is equal to the difference in the quasi Fermi levels of the minority carriers, i.e. electrons in the p-type portion and holes in the n-type portion. Equivalent circuit of a solar cell 3.6.2.5 The schematic symbol of a solar cell To understand the electronic behaviour of a solar cell, it is useful to create a model which is electrically equivalent, and is based on discrete electrical components whose behaviour is well known. An ideal solar cell may be modelled by a current source in parallel with a diode; in practice no solar cell is ideal, so a shunt resistance and a series resistance component are added to the model. The resulting equivalent circuit of a solar cell is shown on the left. Also shown, on the right, is the schematic representation of a solar cell for use in circuit diagrams.

Figure 3.6.2.1 Equivalent Circuit of a solar cell

Figure 3.6.2.2 Cell, Module, Array


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3.6.3 Types of solar cells Silicon is the raw material used to make solar cells. It's the second most abundant element on Earth.

There are three main types: 1. Monocrystalline or single crystal cells

The first generation of solar cells Excellent conversion rate (12 - 16%) (23% under laboratory conditions) Making them is a painstaking, therefore expensive process Another drawback - it takes a lot of energy to obtain pure crystal

2. Polycrystalline cells

Lower production costs, requiring less energy to make 11 - 13% conversion efficiency (18% in the lab)

Figure 3.6.3.1 Single Crystal

Figure3.6.3.2 Polycrystalline cells


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3. Amorphous

o A more recent technology (mid-70's) o Lower production costs, but unfortunately also o Lower efficiency (8 - 10%) (13% in the lab)

3.6.4 Solar panels Theory and construction Solar panels use light energy (photons) from the sun to generate electricity through the photovoltaic effect (this is the photo-electric effect). The structural (load carrying) member of a module can either be the top layer (superstrate) or the back layer (substrate). The majority of modules use wafer-based crystalline silicon cells or a thin-film cell based on cadmium telluride or silicon. Crystalline silicon, which is commonly used in the wafer form in photovoltaic (PV) modules, is derived from silicon, a commonly used semi-conductor. In order to use the cells in practical applications, they must be:

connected electrically to one another and to the rest of the system protected from mechanical damage during manufacture, transport, installation and use (in

particular against hail impact, wind and snow loads). This is especially important for wafer-based silicon cells which are brittle.

protected from moisture, which corrodes metal contacts and interconnects, (and for thin-film cells the transparent conductive oxide layer) thus decreasing performance and lifetime.

Most modules are usually rigid, but there are some flexible modules available, based on thin-film cells. Electrical connections are made in series to achieve a desired output voltage and/or in parallel to provide a desired amount of current source capability.

Diodes are included to avoid overheating of cells in case of partial shading. Since cell heating reduces the operating efficiency it is desirable to minimize the heating. Very few modules incorporate any design features to decrease temperature, however installers try to provide good ventilation behind the module.

Figure 3.6.3.3 Amorphous Cells


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New designs of module include concentrator modules in which the light is concentrated by an array of lenses or mirrors onto an array of small cells. This allows the use of cells with a very high-cost per unit area (such as gallium arsenide) in a cost-competitive way.

Depending on construction, the photovoltaic can cover a range of frequencies of light and can produce electricity from them, but sometimes cannot cover the entire solar spectrum (specifically, ultraviolet, infrared and low or diffused light). Hence much of incident sunlight energy is wasted when used for solar panels, although they can give far higher efficiencies if illuminated with monochromatic light. Another design concept is to split the light into different wavelength ranges and direct the beams onto different cells tuned to the appropriate wavelength ranges.[2] This is projected to raise efficiency by 50%. Also, the use of infrared photovoltaic cells can increase the efficiencies, producing power at night.

Sunlight conversion rates (module efficiencies) can vary from 5-18% in commercial production (solar panels), that can be lower than cell conversion.

The current market leader in efficient solar energy modules is SunPower, whose solar panels have a conversion ratio of 19.3%, with Sanyo having the most efficient modules at 20.4%.[4] However, a whole range of other companies (HoloSun, Gamma Solar, NanoHorizons) are emerging which are also offering new innovations in photovoltaic modules, with a conversion ratio of around 18%. These new innovations include power generation on the front and back sides and increased outputs; however, most of these companies have not yet produced working systems from their design plans, and are mostly still actively improving the technology. As of August 26, 2009 a world record efficiency level of 41.6% has been reached.

Crystalline silicon modules Most solar modules are currently produced from silicon PV cells. These are typically categorized into either monocrystalline or multicrystalline modules. Thin-film modules Third generation solar cells are advanced thin-film cells. They produce high-efficiency conversion at low cost. Rigid thin-film modules In rigid thin film modules, the cell and the module are manufactured in the same production line. The cell is created directly on a glass substrate or superstrate, and the electrical connections are created in situ, a so called "monolithic integration".

The substrate or superstrate is laminated with an encapsulant to a front or back sheet, usually another sheet of glass. The main cell technologies in this category are CdTe, or a-Si, or a-Si+uc-Si tandem, or CIGS (or variant). Amorphous silicon has a sunlight conversion rate of 6-12%. Flexible thin-film modules Flexible thin film cells and modules are created on the same production line by depositing the photoactive layer and other necessary layers on a flexible substrate. If the substrate is an insulator (e.g. polyester or polyimide film) then monolithic integration can be used. If it is a conductor then another technique for electrical connection must be used.


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The cells are assembled into modules by laminating them to a transparent colorless fluoropolymer on the front side (typically ETFE or FEP) and a polymer suitable for bonding to the final substrate on the other side. The only commercially available (in MW quantities) flexible module uses amorphous silicon triple junction (from Unisolar). So-called inverted metamorphic (IMM) multijunction solar cells made on compound-semiconductor technology are just becoming commercialized in July 2008. The University of Michigan's solar car that won the North American Solar challenge in July 2008 used IMM thin-film flexible solar cells.

The requirements for residential and commercial are different in that the residential needs are simple and can be packaged so that as technology at the solar cell progress, the other base line equipment such as the battery, inverter and voltage sensing transfer switch still need to be compacted and unitized for residential use. Commercial use, depending on the size of the service will be limited in the photovoltaic cell arena, and more complex parabolic reflectors and solar concentrators are becoming the dominant technology.

The global flexible and thin-film photovoltaic (PV) market, despite caution in the overall PV industry, is expected to experience a CAGR of over 35% to 2019, surpassing 32GW according to a major new study by IntertechPira.

Standards 3.6.5 Standards generally used in photovoltaic panels:

• IEC 61215 (crystalline silicon performance), 61646 (thin film performance) and 61730 (all modules, safety)

• ISO 9488 Solar energy -- Vocabulary. • UL 1703 • CE mark • Electrical Safety Tester (EST) Series (EST-460, EST-22V, EST-22H, EST-110).

3.6.6 Solar Cell Production Through the electricity can be generated by photovoltaic effect using various semiconductor materials, the most commonly used materials for fabricating solar cell is silicon . The most generally known techniques of making solar cells based on silicon are the monocrystalline, polycrystalline, ribbon and amorphous technology. we shall describe briefly the construction of a standard single crystal Si photovoltaic cell. There are many variations; and commercial competition produces continued revision of cell type and fabrication method. A general design is shown in fig. 3.6.6.1General design criteria (1) Initial materials have to be of high chemical purity with consistent properties. (2) The cells must be mass produced with the minimum cost, but total control of the processes and high levels of precision must be maintained. (3)The final product has to have a lifetime of at least 20 years in exposed and often hostile environments. Even without concentration of the insolation, the cell temperature may range between -30 and=200 c . Elecrical contacts must be maintained and all forms of corrosion avoided . In particular water must be able to enter the fabric. (4) The design must allow for some faults to occur without failure of the compelete system . Thus redundant electrical contacts r=are useful .The parallel and serieds connections between the cells


35

must allow for some cells between faulty without causing an avalanche of further faults. (5)The completed modules have to be safely transported, often to inaccessible and remote areas. 3.6.6.2 Crystal Growth High purity electronic grade base material is obtained in polycrystalline ingots. Impurities should be less than 1 atom in 10 9 , i.e. less than 10 18 atoms per mq . This starter material has to be made into large single crystals.

(1) Czochralski technique. This well -established crystal growing technique consists of doping a small seed crystal into molten material.

3.6.6.3 Slice treatment. The 300 um to 400 um thick slices are then chemically etched . A very thin layer of n - type material is formed by diffusion of donors for the top surface .One method is to heat the slices to 1000 c in a vacuum chamber into which is passed P2O5, but more often the slices are heated in nitrogen with the addition of POCI3. Photolithographic methods may be used to from the grid of electrical contacts. First Ti may be deposited to form a low resistance contact with the Si, then a very thin pd layer to prevent chemical reaction of Ti with Ag; and then the final Ag deposit for the current carrying grid . Other methods depend on screen printing and electroplating. The important antireflection layers are afterwards carefully deposited by vacuum techniques; however the similar properties of textured surfaces are produced merely by chemical etching. The rear surface may be diffused with Al to make a back surface field of P+ on p. on this is laid the rear electrical metal contact as a relatively thick overall layer. The very pure silicon required for semiconductors is obtained by refining elemental silicon which has itself been made from pure materials. In one process for making n-p junctions, the highly purified solid is melted and a controlled amount of boron is added. From this melt, a p-type semiconductor is grown slowly as a single crystal in the form of long cylinder about 8 to 10 cm in diameter. The cylinder is cut into disks, commonly 0.25 to0.35 mm thick; this thickness is necessary in single crystal silicon for effective absorption of the solar radiation. One face of each disk i then exposed to phosphorus vapour at high temperature. The phosphorus atoms diffuse into the silicon to form an n-type layer to a depth of about 1 micrometer or so over the p- layer. An n-p homojunction is thus produced. The product, in which the n- type is exposed to sunlight, is called an n-on-p-type solar cell. Solar cell of the p-on-n-type have also been made , but they were found to be less resistant to space radiation. Since the main initial use of the solar cells have been on space craft , commercial cells were of the n-on-p-type. To complete the cell, electrical contacts, designed to cause minimum obstruction of sunlight are attached to the front and back of the semiconductor material. A transparent cover , with an antireflection coating to reduce loss of solar radiation by reflection , is placed in front of the cell , and the whole is each capsulated to provide protection from damage. 3.6.6.4 Cost Reduction.


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If solar cells are to be used more widely for generating electric power, their cost must be reduced substantially. Some reduction can be achieved by using automatic assembly procedures and improved fabrication techniques , such as ion implantation of depends followed by laser annealing .However, more fundamental technical advances are still necessary. Considerable effort in this direction is being made by government, university, laboratories, semiconductor industry and individuals. Following points are being considered for reducing the cost: (1) Reduction in cost of producing single crystal silicon. (2) Development of less expensive forms of silicon. (3) Less expensive alternative semiconductor material. (4) Utilization of a larger proportion of a solar energy. (5) Alternatives to conventional p-n junctions. (6)Concentrating5 collectors to increase the electric power output per unit area of semiconductor devices. Among the methods being studied for decreasing the cost of single crystal silicon is to grow the material as a continuous ribbon or possibility as a sheet of a required thickness .Growth 0f monocrystalline silicon ribbons can allow for considerable reduction in cost of generated electricity per unit .This is possible because no cutting and polishing operations being involved in ribbon technology. Another advantage of using ribbon is higher packing density because the final cell geometry is suitable for panel integration. A number of programmes for continue ribbon processes are ongoing. The basic objective of all these programmes is to demonstrate the potential for achieving low cost per unit of generated electricity. Small amounts of undesirable impurities are introduced, however from the die through which the molten silicon is drawn. As a result, the conversion efficiencies of the solar cells are generally somewhat less than for cells made from single crystal silicon. This loss of efficiency may be more than offset by the decreased cost of the cells. Instead of expensive single-crystal silicon, it may be possible to make solar cells from cheaper polycrystalline silicon. Polycrystalline material consists of an aggregate of small crystal or gains, rather than a single crystal. In this technology basically the silicon is cast or directly solidified in the shape of an ingot rather than making long single crystals as in the case of single crystal silicon. The wafer which are slicked from the polycrystalline material are semi-crystalline in nature and are processed more or less in the same manner as in the case of single crystalline wafers. To be effective in a cell, the individual silicon grains must exceed a certain minimum size for the solar radiation to be absorbed without crossing a grain boundary .Polycrystalline material of this type can be made by deposition from silicon vapor. Another possibility is to produce material with small grains, which is relatively simple, and then to increase the grain size using laser or electron beam techniques, The efficiencies of polycrystalline silicon solar cells so far observed are yet below 10%. This loss in the efficiency compared to the mono crystalline silicon solar cells is considered to be compensated by the saving in the energy consumed for the production of poll- crystalline technology. A promising alterative to single crystal silicon is the so called amorphous silicon, which is actually an "alloy" of silicon and hydrogen...It is made most readily by passing an electric discharge through


37

the gas silence, a compound of silicon and hydrogen , at low pressure , a thin layer of amorphous silicon hydrogen alloy then deposits on a heated surface . The product can be doped with boron or with phosphorus by adding a controlled amount of a boron hydride or phosphorus hydride respectively, to the saline. The amorphous material is a much better absorber of solar radiation than crystalline silicon, and so a thickness of only 1 micrometer is sufficient for a solar cell. Homojunction p-n cells made from amorphous silicon are cheaper then single -crystal cells, but their photochemical conversion efficiencies have been low .Better results can be obtained with a schottky junction will be described later. The amorphous silicon technology offers thin film solar cells. Because the photo -sensitive layer are very thin, very little material is used and the ultimate costs are low. The processes for fabricating the solar cells from thin film silicon technology are entirely different from that used in the case of monocrystalline, poly crystalline or ribbon technology silicon solar cells. A number of groups are working to develop the amorphous silicon technology. Theoretically it is possible to achieve an efficiency of around 15%. It has been reported that efficiency around 10% has already been achieved. However, the stability of the amorphous silicon solar cells under normal solar energy insulation has yet not been fully established. Research efforts are being directed throughout the world on long term stability of the silicon solar cells that have reproducible parameters. It is possible to increase the efficiency of such solar cells by preparing multilayer cells which would lead to lesser costs. Already the amorphous silicon solar cells have found many applications for various indoor devices such as calculators, electric toys, watches, etc... The basic objective of all the processes so far described aimed to reduce the cost of electricity by photovoltaic processes through the realization of less expensive cells. Various methods have been developed and, ultimately it has been found that amorphous silicon solar cells can really provide low cost direct energy conversion by photovoltaic effect. One of the best semiconductor material for solar cells is gallium arsenide which can be doped like silicon; however, it is too much expensive to use expect in special circumstances. A less efficient, but much less expensive solar cell utilizes a cadmium sulfide - cuprous sulfide hetrojunction .hence, photovoltaic cells can be made of thin micro crystalline films, obtained by spraying or vapour deposition of the sulfides on a conducting base. It should be possible to produce such solar cells in sheets that could be used as roof tiles. A number of techniques are being studied for increasing the conversation efficiency of silicon solar cells. One proposal is based on a combination of two or more cells using different semi conductors materials. In these materials different amounts of energy are required to produce free electron and holes. The principle is that solar radiation that is not effective in one cell will be effective in a succeeding cell. One such combination of such three cells, made from gallium arsenide, silicon and germanium of which the minimum energy requirements are 1.3, 1.1, and 0.8 electron volts, respectively, has a possible conversion efficiency of 40 per cent. Another approach is to shift the solar radiation spectrum in a way that increases the proportion of energy in the effective range for producing free electrons and holes in the given semiconductor In the thermo voltaic cell, this is achieved by absorbing in the solar cell is reflected back to the radiator and is retained in the system . Overall conversion efficiencies of 30 to 50 per cent are considered possible. The cost of photovoltaic cells may perhaps be reduced by alternatives to the conventional p-n


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junctions with two semiconductor materials. One promising possibility is the Scotty junction formed by depositing a thin layer of metallic conductor onto a p or n type semiconductor. A potential barrier is established just as in a conventional p-n junction. Free electrons and holes produced by solar radiation with the appropriate energy then travels in opposite directions under the influence of this potential , in the usual manner .Scotty junction photovoltaic cells made with the so-called amorphous silicon are more efficient homojunction p-n cells of the same material. The MIS solar cell is similar to the Scotty type except that a very thin layer of an insulator is deposited between the semiconductor and the metallic conductor. A conversion efficiency of more than 17 per cent has been reported for an MIS solar cells made with single crystal silicon. 3.6.7 Design of Photovoltaic System To determine the capacity and size of a photovoltaic system (to size the system), it is necessary to select an optimum combination of battery capacity and array size for a perfect location. Methodologies for sizing systems are relatively well-developed and employ an hour-by-hour computer model of the system under consideration. The annual energy output from the system can then be calculated for range of array sizes and battery capacities to select an optimum combination, i.e. the one with the lowest cost. The size of the photovoltaic array and the amount of battery storage required depend on several technical/site factors : (i) Location. Both the quantity of solar energy available (the solar irradiation in kWh/m2/day) and its day-to-day variations have a significant effect on the array size and storage requirements. (ii) Required availability. This is the fraction of the year when energy is available from the photovoltaic system. Any loss in service is due to inadequate insulation. Although an oversized system could probably provide 100 per cent availability, it would most likely be uneconomic. (iii) Duty cycle. The pattern of energy demand influences the system size. For example, a short duty cycle centered on solar noon will require less storage because midday soar irradiance levels are fairly constant. (iv) Energy demand. The major technical factor affecting the cost of the system is energy demand. If a battery is included in the system then power demand is less important. Because of the linear response of photovoltaic cells (i.e. electricity output is directly proportional to solar input), the array and storage size increase linearly with the energy demand. Thus for a given location, given availability and a fixed duty cycle increasing the energy demand by a factor of 2 will require twice the storage capacity and twice the array size. If the power requirements for a fixed duty cycle are doubled, then the energy requirements are also doubled. Photovoltaic systems are already economically viable systems in isolated locations for loads of less than 1KW. In such cases the system is generally a low voltage d.c system and is used to charge storage batteries such a simple photovoltaic system consists of one or more arrays of solar cells, storage battery, blocking diode and a battery charge limiter. The design of such a system would involve: 3.5.7.1 Calculation of array size 3.5.7.2 Calculation of battery capacity 3.6.7.1 Calculation of array size (a) Approximate calculations. This calculation of the size of the array requires data of mean daily


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insulation at the place of installation. Insulation data of major cities of the world are available from records of weather stations located there. For India, "Handbook of solar radiation data for India, "by Armani can be referred, or standard charts of solar radiation on horizontal surface vs time (hrs) for a typical day can be referred. The monthly solar insolation is averaged for a day to obtain solar insolation kWH/m2 day. Graph is available which shows the monthly variation of total radiation in kWH/m2 day or it may be for values of solar insolation in kWH/m2 year. Contours of world wise distribution of solar energy in terms of duration of sun shine are also available. In case the mean daily insolation data of a particular prospective place of installation is not available, it can be approximately computed from the duration of sunshine hours in that region of the world. Typical data for some locations in India are giving below. These values are obtained on horizontal surfaces, at AM1. For Ahmedabad Latitude 22 57’N Mean horizontal insolation kWh/m2 Yearly Solar Insoaltion 2190 kWh/m2 Mean horizontal daily insolation in kWh/m2 = Number of peak sunshine hours (Hpass) Also, Hpass = yearly insolation in kWh/m2 /365 Hpass = 2190/365 Hpass = 6 hrs From insolation data, one can compute the required photovoltaic system output necessary for a given daily load requirement in watt hours. Considering system losses to be 20%, the system output can be computed as System output=(daily load in watt hours+20% system loss)/peak sunshine hours As per previous calculations system output must be 1440W System current=system output/voltage output =1200/230 System output=6.2 amp 3.6.8Voltage can drop for several reasons:

At high temperatures. (Unlike thermal solar energy, PV works less well when it's very hot! In tropical climates, choose higher voltage panels.)

As a result of long wires. It's important to keep your wiring between your panels and other parts of your installation as short as possible.

Diodes can also cause small voltage losses, as we'll see later. Just as voltage can be likened to water pressure in a hose, current can be likened to the flow, or the amount of water (or


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electrons) passing through. A thin hose will take longer to fill a swimming pool than a thicker hose with the same pressure.

A panel that produces 2 amperes sends twice as many electrons as a one-ampere panel. When talking of PV panels, you usually refer to their POWER (measured in WATTS). VOLTAGE (electrical "pressure") is measured in VOLTS CURRENT is measured in AMPERES. POWER (WATTS) is calculated by multiplying these two. VOLTS x AMPERES = WATTS A 24-volt PV panel producing 60 amperes of current has 1440 watts of power. Panels can be connected in series or in parallel. If you take two of these 48-watt panels, you can connect them in SERIES, adding their VOLTAGE, with no change in CURRENT (amps); the result is 12 volts at 100 amps (1200 watts). You can also connect them in PARALLEL, the VOLTAGE stays the same, but you add the CURRENT (amps), which gives you 12 volts at 100 amps, but still 1200 watts as in the case above. 3.6.9 How Much Will My Panels Produce? One square meter of solar panels can produce up to 150 watts of maintenance-free power for up to thirty years. They even work on diffuse light on overcast days, albeit with less output. The voltage produced by PV panels remains roughly the same regardless of the weather, but the current (amps) and the power (watts) will vary. The most important variable to bear in mind when planning a photovoltaic installation is the power output, which will basically depend on four factors:

The peak power of your panels (measured in peak-watts or Wp) Light intensity The number of hours of exposure to the sun and The angle of exposure to the sun

The daily output of a solar pumping system varies with the amount of direct sunlight striking the surface of the solar modules. The more sunlight, the more water pumped. The amount of sunlight varies with weather, time of year, and location. You must know the amount of sunlight in your area before a proper system design can be completed. Also patterns of water usage vary. Some users require more water in summer while other users require the same amount of water in winter or summer. This manual contains "solar maps" that will aid you in determining you solar resource. These maps will provide you with a number called Sun Hours on Tilt, or S.H.O.T., and a color that represents the amount of solar resource for your location and application.

The first step is to determine the pattern of water usage. If the application requires a minimum amount of water each day, the system should be designed to provide this amount of water with the least amount of sunlight. This generally occurs in winter. Solar maps, on the following pages, are provided for both December and June. Users requiring the same amount of water each day should use the December map in the northern hemisphere and the June map in the Southern hemisphere. Systems designed with these maps will provide the required water in winter when the least amount of sunlight or energy is available. They will also provide more water in summer.

If the application requires more water in the summer the system should be designed using the June map in the northern hemisphere and the December map in southern hemisphere. Systems designed with these maps will produce the water required in summer. These systems will produce less water in winter, and in some cases may not provide any water in the winter. These maps also assume that the solar array is fully exposed to sunlight during the entire day and is not shaded by trees or hills.


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The angle the solar array is tilted toward the sun affects the energy produced. In order to produce the most energy the solar array must be pointed directly at the sun with the rays of sunlight falling perpendicular to the surface of the solar array. The S.H.O.T.maps provides the optimal angle the array should be tilted for maximum energy output during that season. In fact, these maps are only accurate when the array is mounted at the angle specified on the map. If the angle is changed, the water produced will decrease.

Users in tropical areas, between -23° and +23° of latitude, should examine both maps to determine the solar resource. Also the array tilt angle in these areas is a concern. Solar arrays in the tropics should not be mounted flat or at angles less than 15° despite the fact the sun may be directly overhead. Arrays mounted at low angles become covered with dirt and debris and lose energy output. Mounting at angles 15° or greater insures that rain and gravity will help keep the modules clean. The solar array surface in the northern hemisphere should be pointed true south. Arrays in the southern hemisphere should be pointed true north. Arrays near the equator can be aimed north or south. 3.6.10 SUN HOURS ON TILT & TILT ANGLE To determine the solar resource, follow these steps: 1. Decide whether to design the system for winter or summer. 2. Find your location on the maps,be sure to use the correct map for summer or winter. Remember the seasons are dependent on the hemisphere. 3. Read the color from the installation site on the map and use the legend to determine the S.H.O.T. value (kiloWatthoursper meter squared per day on a tilted flat plate collector). This value is also known as "Sun Hours on Tilt". This value will be used to select the correct pump and array. 4. Use the scale on the right side of the maps to determine the optimum tilt angle for the solar array. “FS”means facing south and “FN”means facing north. See FIGURE - ARRAY TILT ANGLE in STEP 7- ARRAY MOUNTING to see how this angle is measured on the solar array.


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Figure 3.6.10.1 Map of Asia


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3.7 -Array Mounting Array mounting has a large effect on system performance. There are two common methods for array mounting for solar pumping systems; TRACKING and FIXED. 3.7.1 Tracking Tracking arrays provide additional water output and can reduce overall system cost, especially for large systems.

A solar tracker is a PV rack that rotates on an axis to face the sun as it crosses the sky. It is well known that solar tracking will increase energy yield by 25-50%. For solar pumping, tracking offers even greater gains and benefits that can greatly reduce system cost.

Optimum yield during the peak watering season Tracking offers more water out of smaller, less expensive system by increasing performance when the most water is needed - during long sunny days of the growing season. This is most appropriate for agricultural and seasonal summer uses.

Prevention of pump stalling Many solar pumps experience a disproportionate drop in performance when the sun is at a low angle (early morning and late afternoon). When the PV array output is less than 50%, a centrifugal pump may produce insufficient centrifugal force to achieve the required lift. By causing the pump to run at full speed through a whole sunny day, tracking can often DOUBLE the daily water yield

Water distribution for PV-direct irrigation solar irrigation can be practical without storage device, in some situations. The soil itself stores water during cloudy days! But sun-tracking may be necessary to achieve uniform water distribution. When water flow is reduced, a sprinkler just makes a puddle. A trench or drip line feeds only the first few plants, or the lowest ones. A tracking array minimizes the periods of reduced flow. It makes solar-direct water distribution an option for dry sunny regions.

Expediting the design process The tracking decision as a handy variable in the design process. Often you find a system that produces a little bit less than is needed, but the next larger system costs much more. A tracker is a low-cost means to increase the yield of the smaller system.

When not to use a tracker Tracking is least effective during shorter winter days and cloudy weather. If the need for water is constant during the year or greatest in the winter, or if the climate is very cloudy, then it may be more economical to design the system with more solar watts and no tracker.

Figure 3.7.1.1 Solar Tracking


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3.7.2 FIXED Fixed mounting must be used where trackers are not practical. Also, in small systems, the additional cost of the tracker does not offset the reduction in solar module cost. SD series pumps are generally connected to fixed arrays. 3.7.3 MOUNTING ANGLE Whether using a fixed or tracking array, mounting angle is important for maximum water production. The general principle is simple; the array should be angled directly at the sun at solar noon. The rays of sunlight should be perpendicular to the surface of the array.

The position of the sun changes with the seasons of the year. The tilt angle of the array cannot be perfect for all seasons. Some users are able to change the angle of their array a few times during the year to increase water output. At any time of the year, output can be maximized by adjusting the array to directly face the sun at solar noon. The Sun Hours on Tilt maps, on pages 17 through 23, provide the optimum angle for the season. Here are some simple rules for tilt angle based on the latitude of the location: • Arrays mounted at [latitude + 15 degrees] will maximize output in the winter. Output during the peak of summer will be diminished by about 13%. • Arrays mounted at [latitude – 15 degrees] will maximize output in the summer. Output during the peak of winter will be diminished by about 13%. • Arrays mounted at [latitude] will usually maximize yearly output. Output during the peak of summer and winter will be diminished by about 4%. • Arrays should never be mounted horizontally. A minimum angle of 10 degrees is recommended to prevent dirt build up on the solar modules. Wet and humid locations should use a minimum of 15 degrees to prevent the growth of mold and fungus. However, trackers do have certain drawbacks. • Trackers are difficult and expensive to ship. • Trackers for large systems are heavy structures that require several workers to lift into position. • Trackers require a large metal pole for mounting. • In areas with regular cloud cover, trackers can get "lost" and not point at the sun. • In areas with high winds, trackers can be damaged or blown in wrong direction.

In general, trackers are the preferred method for array mounting in the 400 series systems. The 300 pump is centrifugal and requires the additional RPM early in the morning and late in the day to move water. 400 series systems that cannot use trackers must instead use larger arrays to produce equivalent output. 3.7.4 Theft prevention for solar panels The theft of solar PV panels is often cited as a reason for farmers’ being reluctant to invest in this technology. Here are some suggestions for minimizing the risk of theft: • Try to establish a permanent presence at the water point or pumping installation by erecting a labourer’s home there. This will also help to control poaching and/or stock theft. By incorporating the installation’s solar panels, this residence can in some instances be electrified too!


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• Mark the underside of the panels with the farm name and contact details in nonremovable paint. You can paint the entire underside in your favourite colours. This will be hard work for a thief to clean off. • Keep records of serial numbers of all panels. This is proof that the panels are yours when they are recovered, or when you place an insurance claim. • Put a fence around the PV installation! Or plant a solid wall of cacti or sisal that can only be crossed with a removable arched ladder. • Install the panels on six meter steel poles with a large concrete block as foundation, guy wires for anchorage, and fill the inside of the steel pole with cement. Fit razor wire underneath the panels. This also deters baboons from playing or tampering with your assets. • But above all: make a plan! You would not leave your car parked in town with the key in the ignition; you would not let your stud bull roam freely on a public road. So, do not leave solar panels exposed in the field without at least making it hard for thieves.

Figure 3.7.4.1 Theft Prevention of Solar


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3.8 - Pump cable and pipe Selection 3.8.1 PUMP CABLE Properly selecting and installing wire is essential for pump performance. Solar electricity is very valuable and waste should be avoided. Solar pump installations generally use larger wire than AC systems to avoid power loss. Use the following tables to determine what size of wire to use. The deeper the well, the larger the wire. For all 400 applications, pump cable should be 3 conductors, jacketed cable approved for submersible pumps. Conductors should be stranded for low resistance; solid conductors are not suitable. The preferred colors for the conductors are RED, BLACK, and GREEN. Other colors can be used as long as close attention is paid to polarity. This solar pump offers the perfect cable for solar pumping applications.

Table3.8.1.1 CABLE SELECTION

Table 3.8.1.2 SELECTED CABLE 3.8.2 PIPE Size and type of pipe are important for proper system performance. Larger pipe sizes can be used to reduce friction loss on long horizontal runs. Larger sizes should be avoided in vertical runs because sand in the water may settle and cause blockage. Smaller sizes should not be used because friction losses will increase. Plastic pipe is preferred for all pumps because the smooth surface of the pipe reduces friction loss. 300 series pumps must be used with plastic pipe; the plastic pipe provides a cushioning effect and protects the pump diaphragm from damage. Proper pipe size and type for each pump is listed in the table below:


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Table 3.8.2.1PIPE SIZE and TYPE

3.9 -Water level sensors and pump controls

Water storage & tank indicator Storage of water, especially for an orchard or nursery, can improve the efficiency to a great extent. It can enable you to irrigate according to your needs. It can also serve as excellent back up during a dry spell in monsoon. It allows irrigation during early morning or late evening when there is less evaporation, and the plants can make more efficient use of the water.

Pressurized Water Systems

In some applications, a pressurized water system may be required. A properly sized solar pump may be used in a pressurized water system much the same as a standard AC powered pump (Figure 12). If full-time water is needed, the pressure tank can be oversized to provide sufficient water through the night. Storage batteries may also be used to provide a continuous power source. The solar array is used for battery charging purposes, recharging each day what was used during the night. A charge controller and low voltage disconnect are needed in this type of system.

PUMP MODEL PIPE SIZE PIPE TYPE 300/9 ½” PVC OR POLYETHELYNE

Figure 3.9.1 Water Level Indicator


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4. COMPARISION OF SOLAR SUBMERSIBLE PUMP WITH OTHER TYPE OF PUMPS Table 4.1. Comparison of Solar and Other Remote Watering Systems Pump Type Advantages Disadvantages Solar • Low maintenance

• No fuel costs or spills • Easy to install • Simple and reliable • Unattended operation • System can be made to be mobile

• Potentially high initial cost • Lower output in cloudy weather • Must have good sun exposure between 9 AM and 3 PM

Diesel (or gas) power systems

• Moderate capital costs • Can be portable • Extensive experience available • Easy to install

• Needs maintenance and replacement • Maintenance often inadequate, reducing life • Fuel often expensive and supply intermittent • Noise, dirt and fume problem • Site visits necessary

Windmill • Potentially long-lasting • Works well in windy site

• High maintenance and costly repair • Difficult to find parts • Seasonal disadvantages • Need special tools for installation • Labor intensive • No wind, no power

Gravity • Very low cost • Low maintenance • No fuel costs or spills • Easy to install • Simple and reliable

• Practical in only few places

Ram • Very low cost • Low maintenance • No fuel costs or spills • Easy to install • Simple and reliable

• Requires moving water for operation

Hauling • Lowest initial cost • Excellent mobility

• Lowest initial cost • Excellent mobility


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5. APROXIMATE COST CALCUATION Table 5.1Typical cost for a direct-coupled solar pumping system Item Cost (Rs.) Solar pumping system Item Cost in Rs. 230-volt submersible pump 7500 watt PV panels 1,45,000 Mounting bracket 5000 Pump controller 2000 Inverter controller 17000 120 ft., #12 UF wire 2500 Water Lines 300 ft., 1-in PVC pipe 3000 Fittings/glue 500 Pressure tank indicator 2000 Watering Tank Concrete 5000 Site preparation 5000

TOTAL 194500


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6. MAINTENANCE Most failures of solar pumping systems are caused by pump problems. Sand and silt pulled in by the pump are the primary cause of failure. Filtering out silt or sand at the pump intake with fine mesh screen will prolong the life of the pump.

The amount of maintenance required by solar pumping systems depends on the type and complexity of the system. PV panels generally require very little maintenance; however, pumps, batteries and other components require periodic routine maintenance. Solar pumping systems failures can be avoided with the following preventative maintenance: • Check the tightness of all electrical connections in the system. Battery connections should be cleaned and treated with a corrosion inhibitor available from any auto parts store. • Follow the manufacturer’s recommended maintenance procedures for all batteries. Check the electrolyte level and specific gravity of each cell in the battery. Do not overfill batteries. • Check system wiring. Look for cracks in the insulation of exposed wires. Inspect wires entering and exiting junction boxes for cracks or breaks in the insulation. Replace as necessary. • Check all junction boxes for water damage or corrosion. Check the tightness of the terminal screws and the general condition of the wiring. After inspection, make sure covers on junction boxes are closed and sealed. • Inspect the array-mounting frame to be sure that all mounting hardware is tight. Loose bolts Could result in a damaged panel. Maintain any tie-down anchors. Remove any weeds, tree branches or any other objects that may be shading the PV panel. • Check to see if the panel glass is clean. If it is dirty, simply clean it with a soft cloth, mild detergent and water. Rinse with clean water to prevent the detergent from forming a film on the panel. • Check the operation of switches. Make sure the switch movement is solid. Look for corrosion or charring around contacts. Check fuses with ohmmeter after removing; look for discoloration at their ends.


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7. PRECAUTION Pump should be rigidly mounted on the base-plate; otherwise excessive vibration would

result in undue noise and could even damage the magnetic stator. Pump should be covered adequately for weather protection. However, it is necessary to

provide an air vent for the motor fan Foot-valve should be of minimum 2” size so as to minimise suction losses. Sharp bends should be avoided in the pipe lines. The pump should be used daily for at least 15 minutes Under no circumstances should the surface pump be submerged & exposed directly to water The panels should never be covered with any material (e.g. wire mesh). It will reduce the

output of the pump substantially. Carbon brushes should slide freely in the brush holders, otherwise it will result in failure of

the motor. However, excessive play between the brush and the brush holders will also result in sparking. Only recommended grades of carbon brushes should be used.


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8. LIMITATION Low yield: Solar pumping is not suitable where the requirement is very high. The maximum capacity available with solar is 2 HP. However, the output of the 2 HP pump is equivalent to a normal pump of 4 HP. Variable yield: The water yield of the solar pump changes according to the sunlight. It is highest around noon and least in the early morning and evening. This variability should be taken into consideration while planning the irrigation. Dry operation: The submersible pump has an in-built protection against dry run. However, the surface pumps are very sensitive to dry run. A dry run of 15 minutes or more can cause considerable damage to a surface pump. Water quality: As with any other pump, solar pumps work best if the water is clean, devoid of sand or mud. However, if the water is not so clean, it is advisable to clean the well before installation or use a good filter at the end of the immersed pipe. Theft: Theft of solar panels can be a problem in some areas. So the farmers need to take necessary precautions. Ideally, the solar system should insured against theft as well as natural hazards like lightning. Cost: The initial cost of the system is very high but after using 2 or more years it will totally free of cost.


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9. CASE STUDY Nicaragua Solar Water Pump Location Candelaria, Nicaragua Project Timeframe 2003-2004 People Receiving Water 240 Capacity of Installed Photovoltaic System 1128W System Specifications: 210’ dynamic head 140’ well depth Designed for 8 gpm Tested at 15 gpm Grundfos 11-SQF-2 pump 12 Isofoton 94W 24V panels Cost of the Project $44,665 A remote, poor Nicaraguan village now has fresh water thanks to solar energy. Green Empowerment, in partnership with Asofenix, installed a solar water pump system in 2004 to bring water to the village of Candelaria. Previously, 240 villagers had to rely on a shallow well miles away; women and children spent hours each day hauling the heavy water back to their village. This is one of the first solar water pumping projects in

Nicaragua, a model Asofenix and Green Empowerment can replicate in other communities in need. Green Empowerment’s Program Director recounts the moment when water started pouring. “Everyone stood by while we connected the pump and turned on the solar system. After a few minutes, water started pouring out of the pipe at the well top. The supervisor from the local water authority was obviously impressed, and surprised to see that the water was so clear. People gathered to get some water and enjoy the fact that they really had a water supply in their community. It is beyond description to get across what it means to a community living in extreme heat with nearly no water, to suddenly get good clean water. It is a huge transformation. When we left town, everywhere you looked, there was laundry on the lines - since this was the first time in a while they could afford to use their water to wash their clothes.”

Instead of simply installing a solar water pump, Green Empowerment’s approach is to train the NGO (non-governmental organization), Asofenix, and the community of Candelaria to be technically skilled at design, installation, maintenance, and repair of the renewable energy technology. We believe that projects must be underpinned with sufficient training so that local


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people can understand, build, maintain, and fix the system in order to make it sustainable. The well and distribution system from the tank to individual homes will be provided by the Nicaraguan water authority, ENECAL, supported in part by UNICEF. The solar pumping system was provided and installed by Asofenix and Green Empowerment, with support from the New Earth Foundation, the International Foundation and the EnerGreen Foundation. The community members organized a committee to construct, maintain and collect a small tariff for a reserve fund for future repairs or upgrades. This successful partnership has created the foundation for expanding ecological and innovative projects to improve the quality of life in rural Nicaragua.

Why Solar Pumping is needed A solar-powered water pumping system uses solar energy to power a pump to supply a village with potable water. As more groundwater sources become unsafe for drinking, potable water often needs to be drawn from depths that require pumping. Solar-powered water pumping can access deeper, cleaner water that is not accessible by ropes or manual pumps. Another advantage of solar water pumps is they can be used in deeper wells, where the water table is too low for traditional pumps. In Candelaria, women and children had to walk for miles to the nearest well with enough clean water. For this project, a deep well was drilled in their community, and the solar water pump could draw up the fresh water into a tank, from which it will be distributed by gravity to homes around the community.

How Solar Pump Systems Work The process is broken into 4 basic steps: Electricity Generation: Solar Photovoltaic (PV) panels convert sunlight to electrical flow. The electricity then flows to a controller, which monitors the water level in the well and storage tank to ensure safe pump operation. Pumping: If the sun is shining, the storage tank is not full, and the well is not empty, the pump runs. Water is pumped from the water level in the well to the top of the storage tank, a distance generally called the head or lift. Water Storage: Water is stored in a large tank, usually set on a hill at a point that is high relative to other locations in the village. Excess


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water is pumped to the tank to provide water when the pump is being serviced or cloud cover prevents electricity from being generated.

Water Points: From the tank, water is distributed to water taps at individual homes. Since we depend on gravity to carry the water from the tank through the piping system to the water points, the water points need to be at a lower elevation than the bottom of the storage tank.


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10. CONCLUSION 10.1 SELF ANALYSIS OF PROJECT VIABILITIES As mentioned in the introduction of the chapter, this project was aimed to be designed of 10000 liters of water per day solar submersible water pump for La-Gajjar Machineries Pvt Ltd. According to our view point the project was successful to a large extent. We were able to complete the project as far as the requirement was provided as per our apparent clients. We expect that this project will have an upper edge over the other inverters of same rating, cost & requirement. 10.2 PROBLEM ENCOUNTERED AND POSSIBLE SOLUTIONS Till the date we have not encountered any major problem in design as such. To our knowledge we have tried our level best to make the design, keeping in mind the technical as well as the economical aspects. Our Solar Submersible Pump is basically simple in design. Its Electrical & Mechanical parts are intentionally kept isolated to avoid confusion & for better safety. Though there are always some loopholes in every device in this world. Our major concern in the Pump was the Solar panels which demanded high cost. On student level we couldn’t consider any commercial values. Thus, its run-time & usage is still not having been justified as per our level.


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11. BIBLOGRAPHY Solar energy utilization by G D Rai Manual of La-gajjar machineries PVT LTD Application Guide of Solar submersible pump by Kyocera Solar INC. www.aurore.in Solar cell - Wikipedia, the free encyclopedia.mht Guide manual of NYSERDA Nicaragua%20Solar%20Water%20Pump%20Project%20Profile.pdf

Designing of Solar Submersible Water Pump

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