While solar panels are most efficient in direct sunlight, they still generate power on cloudy, rainy, and even snowy days. Naturally, weather conditions such as clouds, rain, and snow can significantly impact how much energy your system produces. While solar energy thrives in bright, sunny environments, that doesn't mean it. Solar panels continue generating electricity during rain and cloudy weather, though at reduced capacity compared to sunny conditions. When under the sun, a. Solar irradiance, the power per unit area received from the Sun in the form of electromagnetic radiation, is the primary factor affecting solar panel performance.