Can solar panels get too hot?

Like any electronics, solar panels don't perform as well when they get hot. But can they get too hot?

Photo of the sun
Photo credit: Scott Goodwill/Unsplash

When solar panels get hot, they become less effective at generating electricity.

This is because when the temperature increases, electrical resistance increases too. That means that as a solar panel gets hotter, more and more of the electricity it generates is lost as heat within the internal wiring of the panel.

You can look up the datasheet for any solar panel and find out what the power temperature coefficient of the panel is. It’s expressed as a percent reduction of efficiency for every one degree Celsius increase in temperature.

For example, the SunPower X-Series panels have a listed power temperature coefficient of -0.29%/°C. This means that for every 1°C increase in temperature, the panel’s efficiency in converting sunlight into electricity will drop by 0.29%.

Homeowners will notice that their peak power generation is a little lower in the summer than in the spring, even though summer days are longer. That might be because of greater atmospheric haze in the summer, but it’s also due to hotter temperatures.

For the most part, this ends up being a small difference, and most solar homeowners won’t notice or should worry too much about this loss of power due to heat.

One question you might have is: can solar panels get too hot? If they really bake in the summer sun, can they fail?

Fortunately the answer is no, and that’s due to test standards that your solar panels have to meet.

Solar panel test standards: IEC 61215

The California Energy Commission sets safety and performance standards for solar panels that influence the national solar industry.

There are numerous standards that encompass fire safety, electrical safety, and various quality standards. One of the test standards that solar panels must meet is IEC 61215.

IEC 61215 includes many tests aimed at confirming product quality, such as electrical safety, wet weather performance, and hail resistance.

One of the tests in IEC 61215 is thermal cycling.

In the thermal cycling test, the solar panel is placed in a chamber at -40°C (-40°F) and left to “soak” at that temperature for 10 minutes.

The chamber temperature is then increased to 85°C (185°F) and then left to soak again for another 10 minutes.

This test then repeats for another 199 cycles, alternating between extreme heat and cold. The solar panel must be able to survive this abuse to successfully pass this test.

In addition to the thermal cycling test, IEC 61215 specifies a damp heat test. This is another test that exposes the panel to alternating 85°C and -40°C temperatures, but adds in 85% relative humidity too. The damp heat test checks to see if the panel will prevent moisture from entering the panel where it can corrode the electrical components inside.

Test standards make sure that your solar panel will survive the hottest days

While product failures do occasionally happen, these test standards make sure that the vast majority of solar panels installed on homes and businesses will survive any extreme temperatures.

For some additional perspective, remember that solar panels are also used on satellites in space, where they are subjected to even more dramatic temperature extremes.

According to this article on the NASA website, a flat plate in low earth orbit would be expected to hit 249°F.

If solar panels on a satellite can survive the conditions found in space, you can be sure that the panels on your roof will do just fine.


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