Key points:
- Cold weather boosts the efficiency of solar panels. While shorter days, overcast skies and lower sun angles reduce overall output, solar panels actually operate more efficiently in cold temperatures. This means that in winter, solar power remains a functional part of Poland’s electricity mix.
- Even during severe cold spells and record electricity demand in early 2026, solar energy continued to provide a consistent contribution to the grid, accounting for nearly 3% of Poland’s overall generation in January.
Solar PV has a growing role in Poland’s power system
Poland’s electricity system is changing from one dominated by coal to one in which renewables play a big role. For the first time, renewables generated more electricity than coal in June 2025. A significant proportion of new renewable capacity has been delivered by solar PV, supported by the government’s Mój Prąd (My Electricity) programme and installed in houses to protect families from volatile electricity prices.
The rapid expansion of solar PV since 2020 means the country is becoming a major player in the EU market. Between 2020 and 2025, solar capacity increased by more than 500% from 3.79 GW to more than 24 GW. In 2025, solar generated more than 11% of Poland’s electricity.
The growing significance of solar in Poland means its output variability is open to scrutiny. To an extent, a decline in solar generation during winter can be mitigated by increased wind generation and expanding electricity storage capacity.
But, there is a common misconception that solar power does not work at all in winter. However, while solar output is lower in winter than in sunnier seasons, data shows that solar PV still contributes to meeting Poland’s electricity demand.
Lower temperatures can increase the efficiency of solar cells
The performance of PV modules is measured under standard test conditions: 1,000 Watts per square metre (W/m2) of sunlight, 25°C cell temperature and an air mass of 1.5.1Air mass is a measurement of the direct path length sunlight travels through the atmosphere to reach a panel. If the sun was directly overhead, the AM measurement would be AM 1; AM 1.5 represents a lower sun and therefore a longer direct path to the solar panel and less intensity. This standardised performance test determines a solar panel’s ‘rated output’ for power generation.
The actual performance of solar modules is affected by a range of factors, including the strength of sunlight, day length and atmospheric conditions. Plus, several parts of solar panels are affected by temperature.
Although sunlight is needed to produce power, cell heating from sunlight actually leads to reduced voltage and, consequently, lower power output. This is because solar cells contain a semiconductor, a material that can be made to either conduct or block an electrical current. Heat affects the material properties of semiconductors, meaning they work better at lower temperatures. This is also true of semiconductors in other places, like smartphones and computers.
The impact of temperature varies between different solar cell technologies. For silicon, the most common cell material, the expected output reduction (known as the temperature coefficient) is about 0.4-0.5% of rated output for every degree over 25°C. Conversely, cell efficiency increases by the same proportion at lower temperatures. For example, at 10°C, solar panels could produce 6-7.5% more power than its rated output.2Assuming the other standard test condition parameters of 1,000 W/m2 of sunlight and AM of 1.5 stayed the same.
This phenomenon means that the difference in solar potential between countries with a lot of sunlight and the highest potential, such as Namibia, is only slightly more than twice that of countries with the lowest solar potential, such as Ireland.
Despite there being less sunlight, solar plants in Poland still produce power in the winter
The increased efficiency of solar cells at lower temperatures contributes to solar power production in Poland in winter and means that solar panels still generate electricity, even on the shortest days.
Despite short days and bad weather, solar still meaningfully contributed to Poland’s electricity supply during the winter period (1 December 2025 – 28 February 2026).3Entso-E data provided by Instrat.
- In total, solar generated 1,763 GWh over the winter period, about 3.37% of Poland’s overall electricity generation
- Even on 21 December, the shortest day of the year, solar generated over 5 GWh, just over 1% of total electricity generation, while on Christmas Day, it made up over 5% of Poland’s electricity generation
- Poland experienced a prolonged spell of severe cold in January and early February 2026 which led to record levels of demand for electricity, and, consequently, record generation. In January, solar generated 560 GWh, contributing nearly 3% of overall electricity generation.
