Current heat in Czechia reduces solar power plant and panel efficiency

Current high temperatures are reducing the efficiency of solar power plants. Their output has fallen by up to 14 percent in recent days compared with ideal conditions. The reason is that the panels overheat, reducing their efficiency. Sunlight is the most important factor in generating electricity from solar power, and panels perform best at temperatures of around 25 degrees. This is according to comments from industry representatives to the Czech News Agency (CTK).

"Solar panels generate electricity from sunlight, not temperature," said Jan Krčmář, executive director of the Solar Association.

He pointed out that higher temperatures do not mean better performance. "On the contrary, output actually falls slightly at high temperatures," he noted.

The impact of high temperatures on solar panel output was also confirmed by Markéta Chrbolková, co-owner of photovoltaic company Schlieger. "In hot weather, such as the temperatures around 30 degrees we are experiencing now, the surface of a panel can reach as high as 65 degrees. This temperature depends on a number of factors, such as the tilt, the structure and even the wind. The optimal panel temperature is 25 degrees. Each degree above 25 reduces output by around 0.35 percent. In the current heat, when solar panels can reach temperatures of up to 65 degrees, output can therefore fall by around 14 percent," she explained.

According to her, the main reason is the response of silicon, the basic material used in most solar panels. "As the temperature rises, so does the internal energy of the electrons in the silicon, which reduces the voltage in individual cells. This in turn lowers the overall efficiency of converting sunlight into electricity. As temperatures rise, the efficiency of energy conversion falls, mainly because the voltage of the cells in the panel decreases, affecting its output," Chrbolková said.

According to the Solar Association, the ideal conditions for generating electricity from solar power are typical summer days with many hours of sunshine and temperatures around 25 degrees. The tilt of the panels and their cleanliness are also important, since dust and dirt on the panels can also affect their efficiency.

According to Krčmář, it is possible to address the reduced efficiency of solar panels during tropical days, but Czech legislation does not yet allow it. "During periods of extreme heat, installing vertical solar panels for agrivoltaics would make even more sense, but unfortunately this is still prohibited in Czechia. The Ministry of the Environment is now working on an amendment to a decree that could permit this type of installation," Krčmář added.

Czechia experienced its hottest day of the year on Wednesday, with temperatures in many places well above 35 degrees Celsius. Heat has been affecting some parts of the country since the start of the summer holidays, and it is forecast to continue today, particularly in the eastern half of the country.