The apparent angle of the sun north or south of the eath's equatorial plane. The earth's rotation on its axis causes a daily change in the declination.

Wind turbines that operate at a constant rotor revolutions per minute (RPM) and are optimized for energy capture at a given rotor diameter at a particular speed in the wind power curve.

see Peak Watt.

The amount of solar energy that passes through a glazing material, expressed as a percentage.

That portion of an electricity supply system used to deliver electricity from points on the transmission system to consumers.

A window located on the roof of a structure to provide interior building spaces with natural daylight, warmth, and ventilation.

The fossil fuels: coal, oil, and natural gas.

A plot of a wind energy conversion device's power output versus wind speed.

The power required to energize the magnetic field of a generator.

A type of anaerobic digester that has a horizontal tank in which a constant volume of material is added and forces material in the tank to move through the tank and be digested.

The monochromatic irradiance of a surface per unit bandwidth at a particular wavelength, usually expressed in Watts per square meter-nanometer bandwidth.

A deposition process whereby heat is used to break molecules into elemental sources that are then spray deposited on a substrate.

A measure of the unavailable or unusable energy in a system; energy that cannot be converted to another form.

A generator with a single armature coil, which may have many turns and the alternating current output consists of a succession of cycles.

Restrictions on the use of a property.

A solar heating system that uses a liquid as the heat transfer fluid.

A turbine that has a runner with attached blades similar to a propeller used to drive a ship. As water passes over the curved propeller blades, it causes rotation of the shaft.

The percentage of a building's seasonal energy requirements that can be met by a solar energy device(s) or system(s).

A tax credit granted for specific types of investments.

A water and energy conserving device that limits the amount of water that a faucet or showerhead can deliver.