Sharon Klein, associate professor at the University of Maine School of Economics, is featured as an expert on solar panel efficiency at EcoWatchThe 2022 guide to the 10 best solar panels for homes. Klein explained that crystalline solar panels are generally more efficient than thin film, and cloudy weather, shade and temperature all affect the efficiency of solar panels. “Although solar panels work best in direct sunlight, they can also work when light is reflected or diffused by clouds. However, when it’s cloudy, solar panels don’t work at their best high efficiency. They may only operate at 10-25% efficiency, depending on how dense the clouds are. … The shade acts like a cloud, which reduces the efficiency of the solar panel. Solar works best at cooler temperatures. High temperatures reduce efficiency. The best way to determine if your roof is suitable for solar is to ask for free quotes from several local solar installers. They can tell it’s up to you how many panels, what type, your roof will support, whether any wood removal is necessary, and how much it will cost and save you,” Klein said.