How do solar panels work — and do they work in cloudy weather?

Solar photovoltaic (PV) cells convert sunlight directly into electricity; output depends on time of day, location, season, and weather (US EIA).

Solar photovoltaic (PV) devices — solar cells — convert sunlight directly into electricity; small cells power calculators and watches, while larger arrays power homes and feed solar thermal power plants. Separately, solar thermal systems use sunlight to heat water for homes, buildings, or pools, and air inside buildings. Output is not constant: the US Energy Information Administration notes that the amount of available sunlight depends on the time of day, location, season, and weather conditions. That is why two identical arrays in different climates — or on opposite sides of a hill — can produce different annual yields, and why production estimates in a proposal should be tied to local irradiance data rather than generic averages.