Solar power is tapped directly from the sun; which has an intensity on a clear day of 1,000 W / m2 on the ground with the sun directly overhead. Many ways of tapping solar power have been developed. Photovoltaic cells, also called solar cells convert sunlight to electrity directly. Solar energy can be used to heat fluids to drive turbines in electic generators. Plants use photosynthesis to convert solar energy to chemical, which can later be burned as fuel to generate electricity.
Invented by Horace de Saussure, a Swiss naturalist experimenting as early as 1767, a solar box cooker traps the sun's power in an insulated box; for cooking, pasturization and fruit canning. Solar heating is also used to help heat buildings and provide hot water.