What is Temperature Coefficient?
A measure of how much a solar panel's output decreases as temperature rises above 25°C.
Quick Answer
Ireland's cool climate is actually an advantage for solar panels. Panel surface temperatures in Ireland rarely exceed 40°C, compared to 60°C+ in hot countries. This means Irish panels operate closer to their rated efficiency. On a clear summer day in Ireland, panels might lose only 3–5% to heat, compared to 10–15% in Spain or Italy.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
Temperature Coefficient Explained
The temperature coefficient of a solar panel describes the rate at which its power output changes with temperature. It is expressed as a percentage change per degree Celsius (e.g. -0.35%/°C). Since panels are rated at 25°C (STC), every degree above 25°C reduces output by the temperature coefficient amount. For example, at 35°C, a panel with -0.35%/°C coefficient loses 3.5% of its rated output. Lower (less negative) coefficients are better.
How Does Temperature Coefficient Work in Ireland?
Ireland's cool climate is actually an advantage for solar panels. Panel surface temperatures in Ireland rarely exceed 40°C, compared to 60°C+ in hot countries. This means Irish panels operate closer to their rated efficiency. On a clear summer day in Ireland, panels might lose only 3–5% to heat, compared to 10–15% in Spain or Italy.
Frequently Asked Questions
Do solar panels work better in cold weather?
Panels are more efficient in cold temperatures, yes. But cold weather usually means less sunlight. Ireland's moderate temperatures give a good balance of efficiency and light levels.
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John Rooney is the founder of Solar Info and has been covering the Irish solar energy market since 2023. He fact-checks all content against official SEAI data and maintains relationships with SEAI-registered installers across Ireland.