1 Introduction Water is a basic necessity of life. Be it for drinking, irrigation, livestock, or domestic use, there is nothing of such a crucial importance to human health and well-being. Millions of cubic meters are pumped every day all over the world for rural applications, with electricity and onsite generators being utilized as the primary sources of power. Renewable energy started to become more and more of a feasible solution in the recent years given the combination of high energy prices and lowering costs of renewables, especially solar PV technologies, providing farmers and rural residents with environmentally friendly power sources to pump water with clear competitive advantages over traditional fuel-driven generators.

Why Solar Pumping?

Available abundantly, solar energy offers a potentially financially feasible and technically practical solution, with solar water pumping becoming very common in agricultural applications using sophisticated yet well-established technologies to empower water pumps that move water from wells, ponds, and other water sources to ground levels and to end-use locations. Thus, as long as the sun is shining, water is being pumped and moved around either to a water storage location or directly to consumers. When compared to other water pumping methods that have been and are more commonly utilized, such as diesel-powered, wind-powered, human-powered and animal-powered sources, solar pumping has its advantages as demonstrated in Table 1.

Solar water pumping is becoming a more common application in rural areas, primarily used in irrigation and domestic water supply for private homes, camps, villages, rural medical centers and other facilities .

April 2015Exchange Issue 15

Solar - Driven Water Pumping: An Untapped Resource for Lebanon

Guest Author: Mr. Nader Hajj Shehadeh

Energy Consultant, Lebanonnhshehadeh@gmail.com

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Farms, orchards, vineyards, and domestic gardens are using solar pumps for irrigation and cattle watering purposes, with best results and most clear feasibility in application requiring low flow and pressure, making open channels and drip irrigation the most suitable methods when coupled with solar PV pumping.

How does it Work?

The method is simple. Direct current (DC) electricity is produced in a set of silicon solar cells, connected

to a pump that can be located either on the surface or submersible. Surface pumps are mounted at ground level, its inlet linked to the well and its outlet to the water delivery point, while submersible pumps are completely lowered into the water (best applicability for deep wells). Both DC and alternating current (AC) pumps can be used; in the case of AC, an inverter is needed to convert DC to AC. The operation of the pump is controlled by a pump controller that assesses the voltage output of the panels (see Figure 1).

Storage can be done by the use of elevated water

Table 1: Advantages and Disadvantages of various energy sources for water pumping

Figure 1: Typical off-grid surface and submersible solar pumping system sketch

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tanks or storage ponds where water is stored until it is delivered to end-users, or through the use of batteries that store electricity and save it until there is demand for water. The first is more feasible and requires less maintenance compared to battery storage systems.

A typical system consists of four major components that are the PV panels, the solar pump, the controller, and the storage volume. Some systems use batteries as a storage volume while others use water tanks. There are other minor components that are also used such as the mounting structure, wiring, piping, float switch and others.

The PV panels are considered the most important and effective items in the pumping system, making up almost 70% of the overall system cost (assuming no battery storage needed). Panels produce DC electricity, they are interconnected together in series and parallel to achieve the desired voltage and current.

The choice of pump type, size, and capacity depends on the application and its requirements. In principle, submersible pumps are used in wells deeper than 7

meters and pumps installed on the surface are used for shallow wells. DC motors are widely applied in small applications with capacity not exceeding 3 kW [Jekins 2014)] , mainly applicable for small water demand such as gardening, landscaping, small volume livestock watering, etc. DC pumps are more efficient and more practical as they do not require an additional component to convert current to AC. This reduces costs and avoids additional efficiency drops.AC pumps are used for larger applications with capacities exceeding 3 kW, requiring an inverter to change the current that the solar panels produce (DC) to a current that is suitable for the pump (AC). Latest 3-phase pumps use a variable frequency AC motor and a three-phase AC pump controller that enables them to be powered directly by DC power produced by the solar modules.The controller plays a vital role in the system performance due to its ability to regulate the power production to match that produced by the panels with that required by the pump. It also plays a critical role in protecting the system by turning it off when the voltage is at an inappropriate level, meaning too low or too high compared to the operating voltage range of the pump. This voltage protection role helps extend the lifetime of the pump and reduce maintenance requirements.

Figure 2: Typical solar pumping system for irrigation, livestock and domestic water supply

Sizing the Solar Water Pump

There are different factors that affect the applicability of the solar pump and the system’s optimal capacity. The sizing process normally requires the following data:

1) Water source inspection to evaluate the water depth, water level, and delivery capacity and, accordingly, decide on the type of pump and water capacity availableWater demand on site is based on the application and the number of cattle, acres of irrigated area, and/

or number of residents to supply water to. There are some benchmarks used, for example a milking cow consumes 95 liters per day, while a horse consumes 76, and a hectare of rice consumes 100 liters, etc… [Jekins (2014), Gleick (1996), Morales et al (2010)]

2) Total head including dynamic and static head in order to evaluate the friction loss

3) Solar resources online including solar radiation and sun peak hours per day in order to design the PV arrays

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Financial Performance

Solar pumping is most practical and financially feasible when the national grid power line is more than 1 km away from the pump location. The investment that would be made to have a solar-powered water pump makes more sense than that made to extend power lines. On average, extending the power lines costs somewhere between 18 and 36 USD per meter [CEMC (2014), Home Power (2014)], but in Lebanon there is no official data published by EDL on these costs.

International benchmarks are available from previous experiences in developing countries, especially

India. According to a study performed and published on Energypedia.com, the average investment for a 1 kWp solar water pumping system is around $5.93 USD per Wp excluding pumping system, logistics, set-up, reservoir, construction, and water distribution costs. A ready-to-operate system, including pumping system, logistics, set-up, reservoir, construction, and water distribution costs is $11.85 per Wp.

The study goes beyond 1kWp and assesses larger systems of capacities of 2kWp and 4 kWp, to find out that the rate drops to $4.63 per Wp for basic 4kWp system, and $7.59 for a 4kWp ready-to-use system, as shown in Figure 5.

Figure 3: Example solar pump sizing diagram (Mono Pumps Limited, 2007)

4) Required flow rate based on the water consumption profile on site

Based on this data, the pump is sized and the solar PV system is designed accordingly. Some solar pump

manufactures offer simplified graphs allowing the sizing of the complete system through the knowledge of the basic flow and head requirements (see Figure 3).

Figure 5: Investment cost of PV pumps systems for drinking water supply (Energypedia, 2015)

A comparative chart for diesel water pumping and PV water pumping is presented in 6 where methods are compared in terms of m4 delivered, with m4 equals

volume in cubic meters multiplied by the total dynamic head in meters.

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Figure 6: Water pumping cost of diesel compared to PV per m4 (Energypedia, 2015)

Figure 7: Diesel versus solar water pumping breakeven point for different diesel price

In Lebanon, A typical 10 kW solar pumping system for domestic water use delivering 13,000 liters per day would cost around 20,000 USD, assuming that the pump is already available, making an average of $2 per Watt. Smaller systems tend to have a higher USD per watt rate but normally not exceeding $4 per watt.

When compared to conventional diesel generator pumps, it appears that solar pumping pays back the investment in an average of 2 years. Results have shown that a medium size solar pumping system with a head of 80 meters and flowrate of 12 m3/day would break even in two years with diesel at an average price of $0.86 per liter and 2.6 years with diesel at $0.57 per liter, as shown in Figure 7.

For other flowrate and head values, Table 2 shows the breakeven for different values, highlighting in yellow the cases where solar pumping would make sense. The blocks in grey identify cases where there is no alternative pump to be used for solar pumping, in such a case diesel still needs to be used or the solar PV system will be designed to provide electricity

to the existing AC pump.

For example, a water pump with a flow rate requirement of 8 cubic meters per day and a head of 80 meters would break even in 1.3 years (16 months), and a system with 25 cubic meters and 40 meters head would break even in 2.6 years (32 months)

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Solar Pumping for Lebanon

Solar Resource

Lebanon is blessed with good solar radiation levels, varying from a yearly average of 1,700 kWh/m2 in

the least irradiated regions to 2,500 kWh/m2 in those regions with best solar irradiance. Irradiance reaches highest levels during the months of May, June, July, and August, peaking in July at more than 300 kWh/m2 per month, as shown in Figure 8.

Table 2: Years to breakeven - when solar becomes cheaper than the diesel option )Emcon, 2006)

Figure 8: Solar irradiance data for the city of Zahle in the Bekaa (SolarMEDAtlas)

Potential and Opportunities

Solar water pumping has a huge potential in the agricultural sector in Lebanon, where large amounts of water is demanded especially during summer seasons. Yet, it is not very common among farmers and people involved in the agricultural sector. There are no more than 15 projects implemented in Lebanon, with more than 80% of them initiated by the technology provider rather than the farmer himself.

This is an indication of how much there is a lack of awareness among users, and there is a need for more efforts and incentives to make it a viable and applicable solution.

According to the latest statistical review performed by the ministry of agriculture, there are around 175,000 farmers in Lebanon working in various agricultural activities. The total agricultural land is somewhere between 215 and 277 thousand hectares (215,000

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ha reported by ministry of agriculture in 2011, and 277,000 ha reported by the ministry of information in 2010). 25% of this land requires watering according to the ministry of agriculture, making around 54,000 hectares.

The water demand in the agricultural sector is 877 million cubic meters per annum, requiring a pumping power of 260 MWp of solar PV to power pumps, assuming an average total head of 100 meters. If pumped using diesel pumps, these systems consume an annual diesel capacity of 26 million liters, costing $13M at an average diesel price of $0.5.At an average investment rate of $2 per Wp, switching all irrigation pumps to PV requires an overall investment of $53M, leading thus to a payback period of 4 years.

With the utilization of proper financing mechanisms, solar pumping can become more and more financially attractive to farmers and individuals living in rural regions, where the purchasing power is low and it is rarely possible to invest large amounts of money in solutions like solar pumping. This is where NEEREA comes in handy, offering farmers funding opportunities that require no upfront investments, with low interest loans paid over a long period of time.The overall irrigation demand would avoid the consumption of around 26 thousand tons of diesel per year, thus avoiding greenhouse gas emissions of

around 68 thousand tons of carbon dioxide equivalent per year.

Conclusion & Recommendations

To date, Lebanon is not an oil-producing country, remaining highly dependent on foreign resources of fuel for electricity production. This gives renewable energy and especially solar an added value and presents it as a reliable solution contributing to increasing energy security in the country and reducing energy demand.The solar water heaters market is the biggest renewable energy market, being followed by the PV that only started during the past couple of years after the ministry of energy and water through the LCEC launched a green loan financing mechanism with the central bank of Lebanon. This financing option, called NEEREA, offers individuals or institutions interested in implementing a green initiative to benefit from long term loans with very low interest rates.Although there is not much solar pumping projects in operation, there is a significant potential for the development of this sector in Lebanon, especially with the frequent fluctuation of fossil fuel price and the growth of water demand in rural regions where various agricultural activities are abundant.Table 3 presents the main barriers hindering the development of solar pumping in Lebanon that need to be resolved. This includes market-related, technology-related, and regulatory barriers.

Table 3: Major barriers and potential solutions for solar pumping in Lebanon

Having a proper financing mechanism in place, and raising awareness among farmers and end users are definitely game changers. This would push the solar pumping market forward and create an attractive

market place for investors and technology providers.With a payback period ranging from a few months to few years, there is no doubt sola pumping is capable of being the next big thing.

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References

CEMC (2012). Line Extension Charges. Retrieved from http://www.cemc.org/line-extension-charges.asp, Cumberland Electric Membership Corporation

Emcon. (2006). Feasibility Assessment for the Replacement of Diesel Water Pumps with Solar Water Pumps. Windhoek, Namibia: UNDP.

Energypedia (2014, October 6). Photovoltaic (PV) Pumping. Retrieved January 8, 2015, from https://energypedia.info/wiki/Photovoltaic_(PV)_Pumping

Gleick, P. (1996). Basic Water Requirements for Human Activities: Meeting Basic Needs. Water International, 21, 83-92.

Home Power (2014), Line Extension Fees

Jenkins, T. (December 2014). Designing Solar Water Pumping Systems for Livestock. Cooperative Extension Service - Engineering New Mexico Resource Network.

Mono Pumps Limited (2007). Solar Powered Water Pumping. Literature Reference: ART 29/4.

Morales, T., & Busch, J. (2010). Design of Small Photovoltaic (PV) Solar-Powered Water Pump Systems (Technical Note No. 28). Portland, Oregon: Natural Resources Conservation Service.

Ministry of Environment (2010). State and Trends of the Lebanese Environment. Chapter 3: Water Resources.

Copyright © UNDP/CEDRO - 2015

The findings, interpretations and conclusions expressed in this report are those of the authors and do not necessarily represent those of the United Nations Development Programme (UNDP). The Consultant does not guarantee the accuracy of the data included in this report. The boundaries, colors, denominations, and other information shown on maps and images in this work do not imply any judgment on the part of the Consultant or UNDP concerning the legal status of any territory or the endorsement or acceptance of such boundaries. The United Nations Development Programme and the Consultant assume no responsibility of any kind for the use that may be made of the information contained in this report.”