Glossary of Terms


Alternating Current:  Electric Current in which the direction of flow is reversed at frequent intervals, 60 cycles per second.  The type of electrical supplied by utility companies.


Ampere:  A measure of electric current; the flow of electrons.


Amorphous:  The condition of a solid in which the atoms are not arranged in an orderly pattern.


Atoms: The smallest particle of an element that can exist either alone or in combination.


Battery:  Rechargeable electric storage unit that operates on the principle of changing electrical energy into chemical energy by means of a reversible chemical reaction.


Break-even:  The cost of a photovoltaic system at which the cost of the electricity it produces exactly equals the price of electricity from a competing source.


Concentrators:  A photovoltaic module that includes an optical component such as a lens or focusing mirror to direct incident sunlight onto a solar cell or panel.


Direct current:  Electric current that always flows in the same direction: positive to negative. Batteries and photovoltaic cells are all DC devices.


Efficiency:  The percentage of available sunlight converted to electricity by a module or cell.


Electric current:  The volume of electricity propelled by the voltage; a flow of electrons.


Electrons:  An elementary particle consisting of a charge of negative electricity.


Greenwashing:  A policy of utilities that use disproportionately high ratios of renewable versus fossil fuel images and language, while at the same time helping to block renewable energy policies.


Energy:  See Watt-Hour

Grid-connected:  A house or device that receives power from a utility company.


Inverter:  This appliance converts independent DC-power into AC power, or regular household current.


Load:  The lights or appliances run by your electrical system. The amount of electrical power being consumed at any given moment.


Kilowatt:  A thousand watts


Megawatt:  One million watts, 1,000 kilowatts


Off-grid:  See stand-alone.


Peak watts:  The amount of power a photovoltaic device will produce at noon on a clear day with sun approximately overhead when the cell is faced directly toward the sun.


Photovoltaic:  Capable of producing a voltage when exposed to radiant energy, especially light.


Photovoltaic array:  A group of solar electric panels connected together.


Photovoltaic cell:  The basic building block in photovoltaic systems. Sometimes called “Solar Cells.”


Photovoltaic effect:  The conversion of sunlight absorbed by a solar cell directly into electricity.


Photovoltaic module:  A solar electric panel


Power:  See Watt

Semiconductor:  Any material that has limited capacity for conducting an electric curre.


Stand-alone:  An isolated photovoltaic system not connected to a utility electric grid.

Utility:  An electrical supplier serving electric power to customers (such as APS or SRP in Arizona)


Voltage:  A measure of the force or “push” given the electrons in an electric circuit, a measure of electric potential.


Voltage regulator:  An electrical device used to keep voltage at predetermined levels.

Watt:  A unit of Power, one watt is the rate at which work is done when one ampere (A) of current flows through an electrical potential difference of one volt (V). Items like light bulbs are rated in watts. Power is the rate at which energy is generated or consumed and hence is measured in units (e.g. watts) that represent energy per unit time.

Watt-hours:  A unit of Energy, defined as power over a time interval.  One watt of power for one hour is one Watt-Hour.  Often used with the prefixes Mega and Kilo for 1-million and 1-thousand.