The heat produced by combusting a specific quantity and volume of fuel in an oxygen-bomb colorimeter under specific conditions.

The vacancy where an electron would normally exist in a solid; behaves like a positively charged particle.

A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots.

The component of a solar energy heating system that collects solar radiation, and that contains components to absorb solar radiation and transfer the heat to a heat transfer fluid (air or liquid).

The highest possible pressure in a fuel-air mixture before spontaneous ignition occurs.

A component of a heat pump that reverses the refrigerant's direction of flow, allowing the heat pump to switch from cooling to heating or heating to cooling.

An insulation product made of a fibrous material or plastic foams, pressed or extruded into board-like forms. It provides thermal and acoustical insulation strength with low weight, and coverage with few heat loss paths.

The demand of a consumer of electricity at the time of a power supplier's peak system demand.

The planting, cultivation, and harvesting of a single species of crop in a specified area.

A vehicle with an engine capable of operating on two different types of fuels.

Power plants, whose output depends on a factor(s) that cannot be controlled by the power generator because they utilize intermittent resources such as solar energy or the wind.

A measure of the surface burning characteristics of a material.

Sunlight scattered by atmospheric particles and gases so that it arrives at the earth's surface from all directions and can not be focused.

The local climate of specific place or habitat, as influenced by landscape features.

A solar collector in which the absorber is contained in a sealed glass tube, thereby providing for relatively high temperature heat gain.

A single photovoltaic device.

A heating unit where heat is distributed by means of convection or fans.

The amount of money required to secure a specified cash flow at a future date at a specified return.

A current carrier, either an electron or a hole, that is in the minority in a specific layer of a semiconductor material; the diffusion of minority carriers under the action of the cell junction voltage is the current in a photovoltaic device.

That part of an electricity bill that is based on the amount of electrical energy consumed or supplied.