Solar power is energy harnessed from the sun's natural light and heat. Because the sun is infinitely replenishable, solar power is a renewable resource. There are two main types of solar energy production: Photovoltaics (PV) and concentrating solar-thermal power (CSP). CSP is typically only used in large power plants, so you really only need to know PV. PV is the power source of solar panels. Solar panels contain PV cells that absorb energy from sunlight. This conversion of solar energy into electrical energy produces electrical charges that cause electricity to flow through your building's electrical panel.