This metric quantifies how much a panel's power output changes for each degree Celsius change in temperature above or below 25°C. For example, a temperature coefficient of -0.
It's a range for the temperatures at which a panel can produce at its best. Here's an example. A 200-watt panel at 20 degrees Celsius (68 degrees Fahrenheit) might only produce 180 watts when the panel reaches 45 degrees C (113 degrees F). The ideal day for a solar panel is actually cold, sunny and windy.
As such, the manufacturer's performance ratings of solar panels are usually tested at 77°F (25°C) or what's called “standard test conditions.” To get a bit technical, solar panels are rated with specific high and low “temperature coefficients” that represent efficiency losses related to temperature changes above or below 77°F.
When discussing solar panel efficiency and temperature, one crucial term to understand is the “temperature coefficient.” This metric quantifies how much a panel's power output changes for each degree Celsius change in temperature above or below 25°C. The temperature coefficient is expressed as a percentage per degree Celsius.
The maximum temperature solar panels can reach depends on a combination of factors such as solar irradiance, outside air temperature, position of panels and the type of installation, so it is difficult to say the exact number.
When considering solar panels for hot climates, pay attention to the temperature coefficient. This tells you how much efficiency the panel loses for every degree above the standard test temperature of 25°C (77°F). Panels with a lower temperature coefficient, closer to zero, perform better in high temperatures.
Are solar panels rated to operate in a wide temperature range?
Although extreme conditions will affect solar panel performance efficiency, solar panels are rated to operate in a very wide temperature range. Designed to reflect real-world conditions, most solar panels have an operating temperature range wide enough to cover every single day of your system's multi-decade lifetime.