Large, flat boxes with glass covers and dark-colored metal plates inside that absorb and transfer solar energy to a heat transfer fluid.

The physical material upon which a photovoltaic cell is applied.

A heat source, such as a space heater, used to provide more heat than that provided by a primary heating source.

A smokestack or flue for exhausting the products of combustion from a combustion appliance.

The average amount of solar radiation that reaches the earth's upper atmosphere on a surface perpendicular to the sun's rays; equal to 1353 Watts per square meter or 492 Btu per square foot.

The total amount of electricity produced by a power plant.

The two times of the year when the sun crosses the equator and night and day are of equal length; usually occurs on March 21st (spring equinox) and September 23 (fall equinox).

The amount of fuel necessary to generate one kilowatt-hour of electricity.

A photovoltaic device where incident sunlight is split into different spectral regions, with an optical apparatus, that are directed to individual photovoltaic cells that are optimized for converting that spectrum to electricity.

A computer software program that simulates energy consumption of commercial buildings; used for design and auditing purposes.

A common utility monetary measure equal to one-thousandth of a dollar or a tenth of a cent.

In a solar photovoltaic device, an n-type dopant, such as phosphorus, that puts an additional electron into an energy level very near the conduction band; this electron is easily exited into the conduction band where it increases the electrical conductivi ...

The amount of energy an energy storage device or system can store.

A measure of the probability that a system demand will exceed capacity during a given period; often expressed as the estimated number of days over a long period, frequently 10 years or the life of the system.

The storage of compressed air in a container for use to operate a prime mover for electricity generation.

The nominal voltage for which a conductor or electrical appliance is designed; the reference voltage for identification and not necessarily the precise voltage at which it operates.

A unit of mass equal to 1,000 kilograms or 2,204.6 pounds.

The outer casing of a window that sits in a designated opening of a structure and holds the window panes in place.

A small groove scribed into the surface of a solar photovoltaic cell which is filled with metal for contacts.

A solar energy system that produces electricity with a PV module, and collects thermal energy from the module for heating. There are no commercially available systems available (as of 11/97).