Solar energy produced or radiated by the sun. Energy derived from the sun's radiation. Solar energy is used on Earth in various ways. It is used as a passive source of energy, for example, in the form of sunlight that comes through a window and heats up a room, or as an active source, as in the conversion of sunlight to electrical energy in solar cells.The sun has produced energy for billions of years and is the ultimate source for all of the energy sources and fuels that we use today. People have used the sun's rays (solar radiation) for thousands of years for warmth and to dry meat, fruit, and grains. Over time, people developed devices (technologies) to collect solar energy for heat and to convert it into electricity.SolarWorld business customers are lowering their energy bills and helping the environment every day with solar power systems for large & small business.