Manipulating sunlight

There are two main types of solar energy: photovoltaics (PV), and concentrated solar power (CSP), also known as solar thermal power. Photovoltaics convert sunlight directly into electricity using solar cells in solar panels. Concentrated solar power uses sunlight to heat a fluid which generates steam and powers a turbine to create energy. PV currently comprises 98% of global solar energy, with CSP as the remaining 2%.

PV and CSP vary in the way they are used, the energy that is produced, and the materials that are used in their construction. The efficiency of the energy that is produced with PV stays constant with the size of the solar panel and the meaning that using a smaller over a larger solar panel will not increase the rate of energy production. This is because of the Balance-of-System (BOS) components that are also used in solar panels, which includes the hardware, combiner boxes, and inverters. With CSP, bigger is better. As it uses the heat from the sun’s rays, the more sunlight that can be collected the better.

 This system is very similar to the fossil fuel power plants in use today. The major difference being that CSP uses mirrors that reflect the heat from sunlight to heat fluids (instead of burning coal or natural gas), which generate steam to turn turbines. This also makes CSP well suited for hybrid plants, such as combined cycle gas turbine (CCGT), which use solar energy and natural gas to turn turbines, generating energy. With CSP, the energy output from incoming solar energy yields only 16% net electricity. CCGT energy output yields ~55% net electricity, much more than CSP alone.