Solar Glossary of Terms

Alternating current (AC) – Electric current in which the direction of flow is reversed at frequent intervals. The most common type of household electricity.

Ampere or amp (A) – The unit of measurement for the electric current. One amp is produced by an electric force of 1 volt acting across a resistance of 1 ohm.

Current – The flow of electricity between two points. Measured in amps.

Direct current (DC) – Electrical current that flows only in one direction. The most common form of electricity used in boats and RVs.

Disconnect – Switch gear used to connect or disconnect components in a photovoltaic system.

Efficiency – The ratio of output energy to input energy.

Electric Current – The flow of electrical energy (electricity) in a conductor, measured in amperes.

Electrical grid – A large distribution network that delivers electricity over a wide area.

Electricity – The controlled flow of electrons through a conductor.

Energy – Usable power. Measured in kWh.

Inverter – An inverter converts the electricity generated from a solar system from direct current (DC) to alternating current (AC) for use in the home.

Irradiance – The amount of solar energy that strikes a surface during a specific time period. Measured in kilowatts.

Kilowatt (kW) – A unit of electrical power, one thousand watts.

Kilowatt-hour (kWh) – One thousand watts acting over a period of one hour. The kWh is a unit of energy.

Megawatt (MW) – One million watts; 1,000 kilowatts.

NREL – The National Renewable Energy Laboratory. A national lab that concentrates on studying and developing renewable energy sources.

Net metering – A practice used in conjunction with a solar electric system where your electric meter tracks your net power usage, spinning forward when you use electricity from the utility, and spinning backward when your system is generating more electricity than you need.

Open-Circuit Voltage (Voc) – The maximum possible voltage across a photovoltaic cell; the voltage across the cell in sunlight when no current is flowing.

Orientation - A term used to describe the direction that a solar module faces. The two components of orientation are the tilt angle (the angle the panel makes from the horizontal) and the aspect angle (the angle the panel makes from North).

Panel – A term used to describe a solar module.

Peak load – The largest amount of electricity being used at any one point during the day.

Photovoltaic (PV) – The conversion of light into electricity. Photo means "light", voltaic means "electric."

Photovoltaic cell – Made from silicon, this is the basic unit of a solar module that collects the sun's energy.

Photovoltaic module – The layers of glass, plastic, and silicon cells framed in metal, which collect the sun's energy.

Photovoltaic system – A complete set of components that converts sunlight into usable electricity.

PV – Abbreviation for photovoltaic.

Solar energy – Energy from the sun.

Volt (V) – The measurement of the force given the electrons in an electric circuit.

Watt (W) – The unit of electric power done in a unit of time. One ampere of current flowing at a potential of one volt produces one watt of power.

Watt-hour (Wh) – A unit of energy equal to one watt of power being used for one hour.