A unit or measure of solar radiation; 1 calorie per square meter or 3.69 Btu per square foot.

In alternating current, the current goes from zero potential or voltage to a maximum in one direction, back to zero, and then to a maximum potential or voltage in the other direction. The number of complete cycles per second determines the current frequen ...

A hydrocarbon gas obtained from underground sources, often in association with petroleum and coal deposits. It generally contains a high percentage of methane, varying amounts of ethane, and inert gases; used as a heating fuel.

The total amount of electric energy loss in an electric system between the generation source and points of delivery.

An elementary particle of an atom with a negative electrical charge and a mass of 1/1837 of a proton; electrons surround the positively charged nucleus of an atom and determine the chemical properties of an atom.

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 measure of the efficiency of converting a fuel to energy and useful work; useful work and energy output divided by higher heating value of input fuel times 100 (for percent).

One thousand kilowatts, or 1 million watts; standard measure of electric power plant generating capacity.

A house built using passive solar design techniques.

The rate of heat flow required to maintain a specific indoor temperature; usually measured in Btu per hour.

Individual rooms or zones in a building where temperature is controlled separately from other rooms or zones.

A configuration of an electrical circuit in which the voltage is the same across the terminals. The positive reference direction for each resistor current is down through the resistor with the same voltage across each resistor.

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 ...

The amount of heat in a quantity of matter at a specific temperature and pressure.

Any device (or plant) that follows the sun's apparent movement across the sky.

In a given electrical circuit, the amount of current in amperes (i) is equal to the pressure in volts (V) divided by the resistance, in ohms (R).

A type of cooling system that uses a charging and discharging cycle with a thermal or latent heat storage subsystem.

The rate of flow of the wind undisturbed by obstacles.

A corporation, person, agency, authority or other legal entity that owns and/or operates facilities for the generation, transmission, distribution or sale of electricity primarily for use by the public.

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