A measure of the average amount of a specified pollutant or material emitted for a specific type of fuel or process.

The electrical power that oscillates between the magnetic field of an inductor and the electrical field of a capacitor. Reactive power is never converted to non-electrical power. Calculated as the square root of the difference between the square of the ki ...

A solar water or space-heating system in which solar energy is collected, and/or moved by natural convection without using pumps or fans. Passive systems are typically integral collector/storage (ICS; or batch collectors) or thermosyphon systems. The majo ...

A device used to measure total incident solar radiation (direct beam, diffuse, and reflected radiation) per unit time per unit area.

The ability to send or wheel electric power to a customer over a transmission and distribution system that is not owned by the generator (seller) of the power.

The process of using heat that is rejected in one part of a cycle for another function or in another part of the cycle.

The change in direction of a ray of light when it passes through one media to another with differing optical densities.

A device or media that absorbs heat for storage for later use.

The process of producing electricity by transforming other forms or sources of energy into electrical energy; measured in kilowatt-hours.

The value of a personal portfolio, product, or investment after depreciation and interest on debt capital are subtracted from operating income. It can also be thought of as the equivalent worth of all cash flows relative to a base point called the present ...

A lamp where the light beam is focused 2 inches ahead of the lamp reducing the amount of light trapped in the fixture.

A device that produces mechanical energy directly from two heat reservoirs of different temperatures. A machine that converts thermal energy to mechanical energy, such as a steam engine or turbine.

Material such as brick, rock, or stone.

The replacement of a non-functional or ineffective lamp with a new, more efficient lamp.

Thermosyphon systems use a separate storage tank located above the collector. Liquid warmed in the collector rises naturally above the collector, where it is kept until it is needed. The liquid can be either water or a glycol solution. If the fluid is wat ...

The process of implementing measures to reduce peak power demands on a system.

A measure of the effective cooling capacity of a refrigerator, expressed in Btu per hour or in tons, where one (1) ton of capacity is equal to the heat required to melt 2,000 pounds of ice in 24 hours or 12,000 Btu per hour.

An electric current induced by radiant energy.

The generation of an electric current, when two conductors of different metals are joined at their ends to form a circuit, with the two junctions kept at different temperatures.

Any material that has a limited capacity for conducting an electric current. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.