Quick Summary
The temperature coefficient measures how much power a solar panel loses for every degree Celsius the cell temperature rises above Standard Test Conditions (25°C / 77°F). Standard panels have coefficients of -0.34%/°C, while premium HJT panels lose only -0.26%/°C.
On hot summer days, roof temperatures can reach 65°C (149°F). High cell heat reduces silicon conductivity, causing power output drops that can be calculated using the temperature coefficient.
How to Calculate Heat Power Loss
If your panel has a coefficient of -0.34%/°C and the cell temperature is 65°C (40°C above standard 25°C):
📊 Calculation Formula:
Power Loss = 40°C × -0.34%/°C = -13.6% Power Reduction
A 400-watt panel under these conditions will output approximately 345 watts.
Frequently Asked Questions
Do solar panels work better in hot weather?
No. Solar panels generate power from light, not heat. In fact, their efficiency degrades as cell temperatures rise.