SOLAR-BASED SOLAR-BASED UNINTERRUPTED POWER UNINTERRUPTED POWER SUPPLY (UPS)SUPPLY (UPS)

By C. Krishna Sunder (07841A0222)

I. Sireesha (07841A0218)

ABSTRACTABSTRACT

Photovoltaic (PV) solar cells are semiconductor devices that convert sunlight into direct current (DC) electricity.

Groups of PV cells are electrically configured into modules and arrays.

With the appropriate power conversion equipment, PV systems can produce alternating current (AC) compatible with any conventional appliances, and operate in parallel with and interconnected to the utility grid.

PV ARRAY + BALANCE OF SYSTEM COMPONENTS = PV SYSTEM

BLOCK DIAGRAM OF SOLAR BASED BLOCK DIAGRAM OF SOLAR BASED UPSUPS

PV ARRAYS

CHARGE CONTROLLER

BATTERY INVERTER

AC LOAD

DC LOAD

PV TECHNOLOGYPV TECHNOLOGY

Photovoltaic (PV) solar cells as they are often referred to, are semiconductor devices that convert sunlight into direct current (DC) electricity.

A MODULE is the basic building block of photovoltaic systems.

Groups of modules can be interconnected in series and/or parallel to form an ARRAY.

Working of PV cell

TYPES OF PV CELLSTYPES OF PV CELLS

There are four types of PV cells Multicrystalline silicon Monocrystalline silicon Ribbon silicon Thin-film

PHOTOVOLTAIC MODULE PERFORMANCEPHOTOVOLTAIC MODULE PERFORMANCE

Electrical characteristics of photovoltaic modules determine the compatibility with loads.

I-V (current-voltage) curve gives the electrical characteristics.

The current-voltage (I-V) curve is based on the module being under standard conditions of sunlight and module temperature.

It assumes there is no shading on the module.

A TYPICAL CURRENT VOLTAGE

CURVE

FACTORS EFFECTING OUTPUT OF MODULESFACTORS EFFECTING OUTPUT OF MODULES

Tilt Shadowing Temperature of the module Orientation Sunlight conditions Less than one sun will reduce the current output of the module by a

proportional amount.

I-V Curve for an Unshaded Module and for a Module with One Shaded Cell.

I-V Curve for a Module at 250C (770F) and 850C (1850F)

PHOTOVOLTAIC ARRAYS AND MOUNTINGPHOTOVOLTAIC ARRAYS AND MOUNTING

Modules can be connected in series, parallel, or both to increase either output voltage or current to form Arrays.

Combinations of series and parallel connections are also used in arrays. Different types of arrays are developed with different features.

Various ways in which a PV array can be mounted on a building.

• Bracket mounting

• Pole mounting

• Structure mounting

SOLAR CHARGE CONTROLLERSOLAR CHARGE CONTROLLER

The primary function of a charge controller in a stand-alone PV system is to maintain the battery at highest possible state of charge while protecting it from overcharge by the array and from over discharge by the loads.

The important functions of solar charge controller are:

1. Prevent Battery Overcharge

2. Prevent Battery Over discharge

3. Provide Load Control Functions

MAXIMUM POWER POINT TRACKING(MPPT)MAXIMUM POWER POINT TRACKING(MPPT)

THERE ARE THREE TYPES OF CHARGING PROCESSESTHERE ARE THREE TYPES OF CHARGING PROCESSES

Bulk charge Absorption charge Float charge

UN-INTERRUPTIBLE POWER SUPPLYUN-INTERRUPTIBLE POWER SUPPLY

Rectifier & battery charger

Battery

Inverter

BATTERIESBATTERIES

primary functions of a storage battery in a PV system are to:

- Energy Storage Capacity and Autonomy.

- Voltage and Current Stabilization.

- Supply Surge Currents. Two types of storage batteries: Primary and Secondary. There is no “perfect battery” suitable for PV systems in general. Typical batteries used in stand-alone PV systems can deliver up to several

thousand amps under short-circuit conditions, requiring special precautions.

BATTERY SELECTION CRITERIABATTERY SELECTION CRITERIA

Selection of battery depends upon very many factors and will be influenced by system management and climatic conditions.

Special requirements made of the battery in operation can be broadly classified according to :

1. The operating time per year.

2. The type of loads (high or low power drain).

3. The number of cycles per week.

• In general, transparent housings should be preferred.

FACTORS EFFECTING BATTERY FACTORS EFFECTING BATTERY PERFORMANCEPERFORMANCE

Corrosion Battery Gassing Sulfation Stratification Temperature

WORKING OF SOLAR BASED UPS WORKING OF SOLAR BASED UPS SYSTEM SYSTEM 

Two types of PV systems

GRID CONNECTED PV SYSTEMS STAND ALONE PV SYSTEMS

GRID CONNECTED PV SYSTEMSGRID CONNECTED PV SYSTEMS

Operate in parallel with and interconnected with the electric utility grid.

Back-feeds the grid when the PV system output is greater than the on-site load demand.

GRID-INTERTIED SOLAR-ELECTRIC GRID-INTERTIED SOLAR-ELECTRIC SYSTEMS WITH BATTERY BACKUPSYSTEMS WITH BATTERY BACKUP

STAND ALONE PV SYSTEMSSTAND ALONE PV SYSTEMS

Operate independent of the electric utility grid.The load only operates during sunlight hours.For maximizing the power transfer from the array to the

load, impedance matching is to be optimized.Optimum matching for resistive loads can be as high as

94.34% at 25 C. Optimum matching factor for electrolytic loads is

99.83% at 25C.

ECONOMY OF SOLAR BASED UPSECONOMY OF SOLAR BASED UPS

Based on two factors

- Energy payback time

- Energy returned on energy invested (EROEI)

• Another factor – Grid parity

S.NO Functions SAPV ( Euro million)

Thermal ( Euro million)

1 Installation cost

of Power Plants

17 104.35 12 274.44

2 Transmission

and distribution

Nil 5521.45

3 Production cost

Nil 5809.37

COST COMPARISON OF SAPV PANELS VERSUS THERMAL

ADVANTAGESADVANTAGES

   Saves your money Environmentally friendly Independent/ semi-independent Low Maintenance

APPLICATIONSAPPLICATIONS

Remote weather monitoring system.Remote communication system.Satellite communication.Solar power based transport system.

CONCLUSIONCONCLUSION

High life of the equipment.

The excess generated power can be pumped in to the grid.

Per unit cost is much less when compared with the power supply companies.

Power can be supplied to both DC and AC loads.

QUERIESQUERIES