The production of electrical current from light.

An exterior door that protects the primary door.

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

The device in an air conditioner or heat pump through which the refrigerant is circulated and releases heat to the surroundings when a fan blows outside air over the coils. This will return the hot vapor that entered the coil into a hot liquid upon exitin ...

A type of home mortgage that takes into account the energy savings of a home that has cost-effective energy saving improvements that will reduce energy costs thereby allowing the homeowner to more income to the mortgage payment. A borrower can qualify for ...

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).

A type of hydroelectric facility that uses the river flow with very little alteration and little or no impoundment of the water.

A class of energy producer that produces both heat and electricity from a single fuel.

A thermostat that can be set to automatically lower temperatures in an unoccupied house and raise them again before the occupant returns.

In reference to a wind turbine, a condition when the rotor stops turning.

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

The ratio of power produced by a wind energy conversion device to the power in a reference area of the free windstream.

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

A solar energy collection device consisting of containers of water located on a roof that absorb solar energy during the day so that the heat can be used at night or that cools a building by evaporation at night.

The process of modifying a building's structure.

An amount to be paid for energy periodically by a customer without regard to demand or energy consumption.

Energy derived from resources that are regenerative or for all practical purposes can not be depleted. Types of renewable energy resources include moving water (hydro, tidal and wave power), thermal gradients in ocean water, biomass, geothermal energy, so ...

A valve operated by a thermostat that can be installed in solar water heating systems to mix cold water with water from the collector loop to maintain a safe water temperature.

A tubular material used to encase and protect one or more electrical conductors.

The measure of overall efficiency for a variety of appliances. For water heaters, the energy factor is based on three factors: 1) the recovery efficiency, or how efficiently the heat from the energy source is transferred to the water; 2) standby losses, o ...