What is Solar Energy?The sun has produced energy for billions of years. Solar energy is thesun’s rays (solar radiation) that reach the Earth. This energy can be converted into other forms of energy, such as heat and electricity. In the 1830s, the British astronomer John Herschel famously used a solar thermal collector box (a device that absorbs sunlight to collect heat) to cook food during an expedition to Africa. Today, people use the sun's energy for lots of things. Photovoltaic (PV devices) or “solar cells” change sunlight directly into electricity. Individual PV cells are grouped into panels and arrays of panels that canbe used in a wide range of applications ranging from single small cells that charge calculator and watch batteries, to systems that power single homes, to large powerplants covering many acres. Solar panels are used to take the sun’s heat and light energy and changes it into electrical energy.