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Effects of Weather on Solar Panel Performance

Solar panels are widely used to generate electricity from sunlight. They are an efficient, affordable, and clean source of energy, making them grow in popularity across the United States. Given that solar panels generate electricity from the sun, many property owners wonder if solar panels still work, even on cloudy or rainy days. The short answer is yes, solar panels are still effective during cloudy days, even though there are some impacts on their efficiency.

Do Solar Panels Still Work on Cloudy Days?

While solar panels do rely on sunlight to generate electricity, they are still able to produce energy even on cloudy days. According to research by the National Renewable Energy Laboratory (NREL), solar panels can still produce around 25% to 40% of their maximum power output on a cloudy day. This varies depending on the thickness and type of clouds, as well as the type and angle/ positioning of the solar panels.

The amount of electricity generated is reduced compared to a sunny day because the cloud cover blocks some of the sun's rays from reaching the solar panels. Solar cells, one of the components of solar panels, are intentionally designed to absorb energy from the sun, so the fewer direct rays that that the solar panels receive, the lower the amount of energy that it will create.

There is a phenomenon known as the ‘Edge-of-Cloud Effect,’ which can actually cause the energy produced by solar panels spike in overcast conditions. This phenomenon involves the amplification of the sun's rays as they pierce through a cloud, resulting in significantly increased electrical output compared to the usual levels. However, this can cause additional issues as having a sudden burst of high electricity being generated can cause issues with the inverter and the various fuses.

Do Solar Panels Still Work on Rainy Days?

Just like with normal cloud cover, solar panels can still produce energy on rainy or snowy days. However, because sunlight is limited during rainy or snowy conditions, so is energy production. This impact is dependent on the density of the cloud coverage and the type of solar panels.

Rain also has a positive effect on the efficiency of solar panels. This is because rain can help wash away any dust or dirt that may have accumulated on the panels, allowing more sunlight to be absorbed.

Furthermore, rain can also cool down solar panels, which can improve their performance. Solar panels are most efficient at lower temperatures, so the cooling effect of rain can actually increase their electricity output because solar panels produce less power as they receive more heat. Electrons, typically at rest with low energy, are activated by sunlight, resulting in higher energy output. The power generated by a solar panel depends on the difference between an electron's resting state and its sunlight-activated, high-energy phase.

Heat activates electrons, putting them in a high-energy state. With high energy at rest, the difference between their resting and energized states reduces, resulting in less power production. In contrast, cold temperatures keep electrons in low energy states, increasing the power they generate when sunlight activates them. This is why solar panels perform best in cold weather compared to hot weather.

Do Solar Panels Still Work on Snowy Days?

Solar panels are designed to be durable and withstand various weather conditions, including snow. They can still operate on snowy days, but their efficiency may be impacted depending on the type of snowfall. Light snow or a thin layer of snow may not have much effect on solar panel performance since the sunlight can still penetrate through it to reach the solar cells. However, heavy or wet snow that completely covers the solar panels can significantly reduce their energy production. This is easily returned back to normal once the snow melts or slides off the angled solar panels.

Does Fog Affect Solar Panels?

Fog can also impact solar panel performance, but to a lesser extent compared to rain or snow. During foggy conditions, solar panels generally operate at about 50% efficiency. The moisture in the air diffuses sunlight, which reduces the amount of light that reaches the solar panels. This decrease in sunlight ultimately leads to reduced power production.

Advances in technology have greatly increased solar panel performance over the past few years, making solar energy an efficient and affordable source of clean energy generation in the U.S. Although weather impacts solar panel performance, solar irradiance (the power per unit area received from the sun in the form of electromagnetic radiation) is just one of the many factors that solar energy developers consider as they evaluate parcels of interest and plan new projects. If you're interested in learning your land's value for a solar lease or purchase, generate your free property report on LandGate's map:


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