Solar Energy

Solar energy is the light and heat energy that comes from the sun.  Several processes can be used to convert this light and heat into electricity, including photovotiac and solar thermal technologies.

Photovoltaic Technologies

Photovoltaic (PV) technologies convert sunlight into electricity using solar cells made from specially processed semiconductor materials such as silicon. There are many variations of PV technologies.

Flat Plate PV use modules made up of multiple solar cells. These modules can be fixed or made to track the sun throughout the day. Generally, tracking units generate more electricity than non-tracking units. 

                 Fixed flat plate PV                                                      Single axis tracking PV                                                            “Tilted” PV trackers

A variant of Flat Plate PV, called High Concentration PV (HCPV),  uses plastic lenses or glass mirrors to harvest the sunlight and concentrate the light onto very high efficiency solar cells. HCPV uses much less of the semiconductor material to generate electricity and therefore has the potential to produce the lowest cost photovoltaic solar electricity.

                                                              HCPV using lenses                                                           HCPV using mirrors

Solar Thermal Technologies

Solar Thermal technologies use solar energy to heat a liquid unit until it boils and produces a vapor. This vapor in turn powers a turbine/generator that generates electricity, or powers a heat engine connected to an electric generator to generate electricity. Solar thermal systems can also use Stirling heat engine or combustion turbine located at the focus of a solar concentrating mirror. See the photos below for an illustration.

                       Parabolic Trough                                                               Power Tower                                                                     Dish Stirling system