Nightmare for photovoltaics. Energy efficiency of panels drops dramatically

• Heat does not have a beneficial effect on energy production by photovoltaic panels.
• Experts point out that at temperatures exceeding 35 degrees Celsius in the shade, the efficiency of the installation drops by about 20 percent compared to the nominal power.
• These losses do not significantly harm prosumers or solar energy in general. According to experts, with long days of high sunlight, panels in the summer still achieve their highest annual production levels.

In recent days, a heat wave has been sweeping through Poland. It turns out that high temperatures are not indifferent to photovoltaics. It would seem that the more sun, the better, however - as broker and energy expert Maciej Wojtuszek explains in an interview with PortalSamorzadowy.pl - photovoltaics do not really tolerate heat .

Strong sunlight and high temperature cause the energy efficiency of photovoltaic panels to drop dramatically . However, we must remember that in the summer, in addition to high temperatures, we also have longer days, so this balances out.

- indicates.

The Ministry of Climate reports that at the end of the first quarter of 2025, there were already 1,542,019 prosumers operating in Poland. Most of them have photovoltaic micro-installations of up to 50 kW of installed capacity.

Prosumer installations are an extremely important element of the Polish energy transformation. That is why we allocate billions for investments that support the development of this type of energy located close to the needs of recipients and focused on consumption at the place of energy acquisition. The Energy Support Fund is PLN 70 billion , intended, among others, for the development and modernization of power grids, so that prosumers can also connect to the network and effectively use the settlements they are entitled to

- says the Minister of Climate and Environment, Paulina Hennig-Kloska.

Photovoltaics expert at E.ON Polska, Dariusz Jóźwiak, explains in an interview with Businnes Insider that "photovoltaic cells, which convert solar radiation energy into electrical energy , are made of silicon, which absorbs less light at high temperatures. In hot weather, the modules cannot therefore operate at their nominal power, and the drop in their efficiency is determined by the maximum power parameter."

Manufacturers provide it in the module product cards. According to the commonly used NOCT (Nominal Cell Temperature) standard, the standard temperature is 25 degrees Celsius , and the power loss factor is from 0.3 to 0.5 percent for each degree Celsius more

- indicates the specialist.

It turns out that if the air temperature in the shade is 35 degrees Celsius, the module will heat up to about 70 degrees Celsius. Then - as explained by the president of the Trend Institute and vice-president of the Association of the Photovoltaic Industry and Energy Storage, Bogdan Szymański - the efficiency of the installation drops by about 20 percent in relation to the nominal power that is written on the nameplate.

The best conditions for PV productivity actually occur around the turn of March and April, when temperatures are relatively low - around 5-10 degrees Celsius - and sunlight is high.

- says Szymański in an interview with Business Insider.

However, it should be remembered that the decrease in efficiency is taken into account when selecting a prosumer micro-installation. " The modules can be up to 30 percent more powerful than the inverters that convert direct current to alternating current that can be consumed or fed into the grid; precisely to compensate for the loss," we read in Business Insider.

The drop in efficiency is not the only problem, as it turns out that high temperatures shorten the life of the installation if the difference between day and night temperatures is very significant. However, in our latitude this is rare.

In summary, at very high temperatures, the efficiency of modules drops significantly, but it does not significantly harm prosumers or solar energy in general. According to experts, with long days of high sunlight, panels in the summer still achieve the highest annual production levels.