On sunny days, solar panels will generate more renewable energy than they will on cloudy ones. On a cloudy day, solar panel outputs fall to an estimated 10-25% of their standard power output. When it snows, that snow usually doesn't completely block the sunlight from getting to the panels so there is still some production. Without a very thick blanket of snow, enough light will penetrate the snow and allow the panels to generate electricity. Also, when the light hits the dark surface of the panels, it will begin to heat up and melt the snow. However, solar panels will have reduced functionality with snow on them.