A colorless, odorless, tasteless gas composed of one molecule of Carbon and four of hydrogen, which is highly flammable. It is the main constituent of "natural gas" that is formed naturally by methanogenic, anaerobic bacteria or can be manufactured, and w ...

A type of heating appliance that performs more than one function, for example space and water heating.

The value or purchasing power of a dollar that has not been reduced to a common basis of constant purchasing power, but instead reflects anticipated future inflation; when used in computations the assumed inflation rate must be stated.

A heat exchanger in a solar water heating system that has two distinct walls between the heat transfer fluid and the domestic water, to ensure that there is no mixing of the two.

A term for the process of transmitting electricity over transmission lines not owned by the supplier of the electricity to a retail customer of the supplier. With retail wheeling, an electricity consumer can secure their own supply of electricity from a b ...

The lowest wind speed at which a wind turbine begins producing useable power.

Transmit high-voltage electricity from the transformer to the electric distribution system.

In reference to solar thermal collectors, the condition where the heat transfer fluid is flowing through the collector loop under normal operating conditions.

A nationally recognized energy rating program that gives builders, mortgage lenders, secondary lending markets, homeowners, sellers, and buyers a precise evaluation of energy losing deficiency's in homes. Builders can use this system to gauge the energy q ...

The process of removing moisture; involves evaporation.

A measure of the efficacy (efficiency) of lamps. It indicates the amount of light (lumens) emitted by the lamp for each unit of electrical power (Watts) used.

In reference to solar photovoltaic cell manufacure, a method of growing a large-size, high-quality crystal whereby coils heat a polycrystalline ingot placed atop a single-crystal seed. As the coils are slowly raised the molten interface beneath the coils ...

The height above the ground that a horizontal axis wind turbine's hub is located.

The amount of energy absorbed (or converted) by a solar collector (or photovoltaic cell or module) over a 15 minute period.

A thermodynamic property of a substance, defined as the sum of its internal energy plus the pressure of the substance times its volume, divided by the mechanical equivalent of heat. The total heat content of air; the sum of the enthalpies of dry air and w ...

A type of heating system that provides heat from the resistance of an electrical current flowing through a conductor.

A device that that converts direct current electricity (from for example a solar photovoltaic module or array) to alternating current for use directly to operate appliances or to supply power to a electricity grid.

Insulation made from rockwool fibers, fiberglass, cellulose fiber, vermiculite or perlite minerals, and composed of loose fibers or granules can be applied by pouring directly from the bag or with a blower.

The flow rate in these systems is 1/8 to 1/5 the rate of most solar water heating systems. The low-flow systems take advantage of stratification in the storage tank and theoretically allows for the use of smaller diameter piping to and from the collector ...

A high-efficiency photovoltaic device containing two or more cell junctions, each of which is optimized for a particular part of the solar spectrum.