How Solar Power Works

There are two basic solar energy technologies, Concentrating Solar Power and Photovoltaic.

Concentrating Solar Power (CSP) uses mirrors to concentrate the sun’s energy on a localized focus point to heat a medium which then is used to convert water into steam to drive a conventional steam turbine, and an electrical generator. There are several types of CSP facilities, with the concentrating solar trough design being the most popular in the industry today. This design uses a series of long, curved mirrors to concentrate the sun’s energy onto pipes located at the focal point of the mirrors. The pipes contain a specialized heat conducting liquid which is pumped to a central boiler that produces the steam to drive the turbine. This is a water-intensive process as large amounts of cooling water is consumed to condense the steam and to replenish the water supply in the boiler loop. CSP projects are typically large in scale.

Photovoltaic (PV) technology uses specially formulated semiconductor cells to convert photons from the sun directly into electrons and electric energy. The PV cells consist of specially formulated layers on a slice of silicon. Several slices of silicon are then placed under a thin slice of glass to make a PV module. As the protons in sunlight strike the PV cells, they knock the neutrons off the silicon. The negatively charged free neutrons are attracted to the silicon but are trapped by the magnetic field that is formed from the opposing fields in the deposited layers. Small wires on the silicon catch these free neutrons and an electric current is formed. The PV modules can be used individually, such as for powering emergency road side telephones, or in groups to form a rooftop solar panel array. Recent advances in PV technology and manufacturing now facilitate large deployments of PV modules in ground-mounted groups to form utility-scale solar power generating facilities.