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Technology SYLLABUS FOR PV SOLAR INSTALLER: How much a 100watt module can produce energy.

Sunday, May 23, 2010

How much a 100watt module can produce energy.


The 100watt module will produce only 67watt. The efficiency can be increased to 77watt by adopting high efficiency modules and minimize other factors. In general energy calculation we take efficiency 77%
The PV solar plant consists of series and parallel connected modules. The specifications printed on the module are based on STC condition. Suppose module rated power is 120watt, it says that module will produce 120 watt power at 25°C cell temperature, 1.5 air mass and 1000watt/m^2 solar irradiance. In the actual practice this can not be achieved. There are so many factors which affects the plant efficiency.
1.     Module tolerances:  On the name plate of module “+/-5%” is written. It means that 100 watt module can generate 105watt or 95watt,  still the module is called 100watt module. For safety factor 95watt is considered. Its efficiency factor is 0.95
2.     Temperature: The output power of module decrease as temperature increases. In the summer season when the ambient temperature is 50°C than the module cell temperature will be 80°C on the roof top of building (30°C above ambient temp.). For crystalline module the temperature reduction factor is 0.89. It varies from manufactured technology of module.
3.     Dirt and dust: Bird spikes and accumulation of sand on the on the module surface, blocking some of the sunlight and reducing the output. A typical annual dust reduction factor is 0.93.
4.     Mismatch and wiring losses: The maximum output of the total array is less than the sum of individual modules. The difference is a result of slight inconsistencies in performance from one module to the next and is called module mismatch factor and amounts to at least 2%. Power is also lost in resistance of wiring. The wiring loss 3%. The total loss factor is 0.95.
5.     Dc to Ac conversion losses: The Dc power generated by modules converted in Ac power by inverters, this again causes losses anf loss factor is 0.9.
The total losses are products of 1 to 5 factors and are equal to:
 0.95x0.89x0.93x 0.95x0.9 =67watt. It means that 100watt module will generates only 67watt.
     6. If battery is used for back up an additional loss of 6 to 10%
7. Array oriental losses: Array gives maximum power in south facing and lilt equal to  latitude. But compromise  is made to avoid shading effect and old odd pitched roofs. These again lossess 2 to 6%.

3 comments:

Alexander said...

Good post very informative

Voltage Inverter DC To AC said...

You explain in great detail, thank you for sharing.

Voltage Inverter DC To AC said...

Thank you for sharing.