Temperature affects the over all Efficiency of solar array. For example a solar array lose about –4% of it’s output for every °C rise in temperature above 25°C.
-0.4% is called temperature coefficient. Now this Temperature coefficient must be taken into consideration during PV-modules design.
Let look at a practical examples.
- At 35°C a solar panel install on the roof top will have a higher temperature of about 15-20°C higher. Which means the solar array is having a temperature of about 55°C.
- 35°C is the ambient temperature with 55°C is the temperature of the solar array on top of the roof.
How to calculate the percentage lost in output due to temperature rise above STC which is 25°C
55-25= 30°C Rise in temperature above STC condition of 25°C
30°C x -(0.4%) which temperature coefficient
This means there is a lost of 12% of the total output power of the solar array. This very significant lost.
Finally Temperature coefficient is very significant factor to consider during solar systems design especially in hot climate.
HOW TO REDUCE TEMPERATURE RISE OF SOLAR ARRAY
- Always use PV mounting kits
- Give allowance of about 1 to 2 inches between the solar array and roof top for air cooling.
- Artificial cooling method should be employ for mini grid systems.
- Compensate for output lost due temperature rise must be factored in.
- Always study carefully, the data sheet of all types of pv-modules.