Alternating Current (AC):
Electrical current (flow of electrons) in which the direction of flow is reversed at constant intervals, such as 60 cycles per second.
Array:
A collection of photovoltaic modules electrically wired together in one structure to produce a specific amount of power.
British Thermal Unit (Btu):
The quantity of heat needed to raise the temperature of 1 pound of water by 1°F at or near 39.2°F.
Charge Controller:
A component of a photovoltaic system that controls the flow of current to and from the battery subsystem to protect batteries from overcharge, over discharge, or other control functions. The charge controller may also monitor system operational status.
Cogeneration:
The production of electricity and another form of useful energy (such as heat or steam) used for industrial, commercial, heating, or cooling purposes.
Commercial Building:
A building with more than 50 percent of its floor space used for commercial activities. Commercial buildings include stores, offices, schools, churches, gymnasiums, libraries, museums, hospitals, clinics, warehouses, and jails. Government buildings are also included, except buildings on military bases or reservations.
Commercial Sector:
Business establishments that are not engaged in transportation or in manufacturing or other types of industrial activity (agriculture, mining, or construction). Commercial establishments include hotels, motels, restaurants, wholesale businesses, retail stores, laundries, and other service enterprises; religious and nonprofit organizations; health, social, and educational institutions; and federal, state, and local governments. Street lights, pumps, bridges, and public services are also included if the establishment operating them is considered commercial.
Conversion Factor:
A number that translates units of one system into corresponding values of another system. Conversion factors can be used to translate physical units of measure for various fuels into Btu equivalents.
Direct Current (DC):
Electric current (flow of electrons) in which the flow is in only one direction.
Duty Rating:
The amount of time an inverter (power conditioning unit) can produce at full rated power.
Electric Power Plant:
A station containing prime movers, electric generators, and auxiliary equipment for converting mechanical, chemical, and/or fission energy into electric energy.
Electricity Generation:
The process of producing electric energy or transforming other forms of energy into electric energy. Also, the amount of electric energy produced or ex pressed in watt-hours (Wh).
Energy:
The capacity for doing work as measured by the capability of doing work (potential energy), or the conversion of this capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be changed to another form useful for work. Most of the world’s convertible energy comes from fossil fuels that are burned to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. Electrical energy is usually measured in kilowatt-hours, while heat energy is usually measured in British thermal units.
Energy Consumption:
The use of energy as a source of heat or power or as an input in the manufacturing process.
Energy Source:
A substance, such as oil, natural gas, or coal, that supplies heat or power. Electricity and renewable forms of energy, such as wood, waste, geothermal, wind, and solar, are considered to be energy sources.
Federal Energy Regulatory Commission (FERC):
The federal agency with jurisdiction over interstate electricity sales, wholesale electric rates, hydroelectric licensing, natural gas pricing, oil pipeline rates, and gas pipeline certification. FERC is an independent regulatory agency within the Department of Energy and is the successor to the Federal Power Commission.
Grid:
Series of local power wires, neighborhood distribution towers, electrical sub-stations, and large scale transmission towers in a region, as seen from a regional map the electrical power lines appear as a type of grid pattern.
Independent Power Producer:
Wholesale electricity producers (other than qualifying facilities under the Public Utilities Regulatory Policies Act of 1978) that are unaffiliated with franchised utilities in the area in which the independent power producers are selling power and that lack significant marketing power. Unlike traditional electric utilities, independent power producers do not possess transmission facilities that are essential to their customers and do not sell power in any retail service territory where they have a franchise.
Industrial Sector:
Manufacturing industries, which make up the largest part of the sector, along with mining, construction, agriculture, fisheries, and forestry. Establishments in this sector range from steel mills, to small farms, to companies assembling electronic components.
Insolation:
The amount of energy in sunlight reaching an area. Usually expressed in watts per square meter (W/m^2), but also expressed on a daily basis as watts per square meter per day (W/m^2/day).
Load:
Any device or appliance in an electrical circuit that uses power, such as a light bulb.
Module:
A number of photovoltaic cells wired together to form a unit, usually in a sealed frame of convenient size for handling and assembling into arrays. Also called a panel.
Peak Sun Hours:
The equivalent number of hours when solar insolation averages 1000 watts per square meter and produces the same total insolation as actual sun conditions.
Photovoltaic Energy:
Direct-current electricity generated from sunlight through solid-state semiconductor devices that have no moving parts.
Photovoltaic (PV) System:
A complete set of interconnect components for converting sunlight into electricity by the photovoltaic process, including array, balance-of-system components, and the load.
Renewable Energy:
Energy obtained from sources that are essentially inexhaustible (unlike, for example, fossil fuels, of which there is a finite supply). Renewable sources of energy include conventional hydroelectric power, wood, waste, geothermal, wind, photovoltaic, and solar thermal energy.
Root Mean Square (RMS):
The square root of the average square of the instantaneous values of an AC output. For a sine wave the RMS value is 0.707 times the peak value. The equivalent value of AC current, I, that will produce the same heating in a conductor with resistance, R, as a DC current of value I.the corrosion of the protected structure.
Solar Insolation (Insolation):
The solar radiation incident on an area over time. Equivalent to energy and usually expressed in kilowatt-hours per square meter.
Varistor:
A voltage-dependant variable resistor. Normally used to protect sensitive equipment from power spikes or lightning strikes by shunting the energy to ground.
Voltage (V):
A measure of the force or "push" given the electrons in an electrical circuit; a measure of electrical potential. One volt produces one amp of current when acting against a resistance of one ohm.
Watt (W):
A measure of electrical power or amount of work done in a unit of time and equal to the rate of current flow (amps) multiplied by the voltage of that flow (volts). One amp of current flowing at a potential of one volt produces one watt of power.
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