Solar Mechanics, Inc. © 2008
AC - see alternating current

Alternating current (AC)
- The most common type of household electricity.  Standard AC wall power.

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.

Ampere-Hour (Ah/AH
) - A measure of the flow of current (in amperes) over one hour; used to measure battery capacity.

- California Energy Commission

- Carbon Dioxide

- California Public Utilities Commission

- California Solar Initiative

Circuit breaker
- A safety device that shuts off power when it senses too much current.

- A material that is used to convey electricity, i.e. wires.

- The flow of electricity between two points. Measured in amps.

- see direct current

Direct current (DC)
- What comes out of PV modules and is commonly used by cars, household batteries, flashlights, toys, etc.

- Database for State Incentives for Renewable Energy

- see LADWP

- 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.

Electrical panel
- an electrical distribution board that houses electrical circuit breakers. It is the main point at which electricity is distributed throughout a building. It is otherwise known as a breaker box. The circuit breakers can be turned on or off, thus restricting or permitting the flow of electrical current to electrical outlets.

- The controlled flow of electrons through a conductor.

- Usable power. Measured in kWh.

Fossil fuels
- Fuels that are formed underground from the remains of dead plants and animals. i.e. oil, natural gas, and coal are fossil fuels.

Greenhouse effect
- When heat from the sun becomes trapped in the Earth's atmosphere due to certain gases.

Greenhouse gases
- The gases responsible for trapping heat from the sun within the Earth's atmosphere. i.e. water vapor, carbon dioxide, methane, ozone, chlorofluorocarbons, and nitrogen oxides.

- A distribution network, including towers, poles, and wires that a utility uses to deliver electricity.

Grid-connected PV system
- A solar system that is tied in to the utility's network. When generating more power than necessary, the system supplies the surplus to the grid. At night, the system draws power from the grid.

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

- 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.  A typical household requires a solar power system that produces between 3-5 kW.

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

- Los Angeles Department of Water and Power

- Anything that is connected to an electrical circuit and draws power from that circuit. Usually expressed in terms of amperes or watts in reference to electricity.

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

- see photovoltaic module

- North American Board of Certified Energy Practitioners

Net metering
- an agreement between a solar system owner and the local electric utility that allows the system owner to buy and sell energy in the form of electric credits. When the solar system produces excess energy, it is sold back to the electric utility at peak prices, literally causing the electric meter to spin backwards. When the system is not producing energy, the system owner can use the credits to buy back energy at off-peak prices.

- On-grid, grid-connected or grid-tied means connected to the utility electrical grid. 

- Off-grid refers to systems that are not connected to the utility electrical grid.  These systems generally include batteries to store power.

- 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 (PVE) Effect
- The phenomenon that occurs when photons, the "particles" in a beam of light, knock electrons loose from the atoms they strike. When this property of light is combined with the properties of semiconductors, electrons flow in one direction across a junction, setting up a voltage. With the addition of circuitry, current will flow and electric power will be available.

Photovoltaic array
- An interconnected system of solar modules that function as a single electricity-producing unit.

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.

- Pacific Gas & Energy

- Abbreviation for photovoltaic.

Rated power
- Nominal power output of an inverter; some units cannot produce rated power continuously.

- Southern California Edison

Silicon (Si)
- A chemical element that is the most common semiconductor material used in making PV cells.

- This man-made compound is abundant in Beverly Hills, CA.

Solar cell
- see photovoltaic cell

Solar electricity
- Solar power.

Solar energy
- Energy from the sun.

Solar module
- see photovoltaic module

Solar power
- Electricity generated from sunlight.

Tilt angle
- The angle of inclination of a module measured from the horizontal.

Utility Meter -
a device that measures the flow of electricity between a site that uses electricity and the electric utility company

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.