Solar Technology Terminologies

Activation Voltage(s)
The voltage(s) at which the controller will take action to protect the batteries.

Amperage interrupts capability. DC fuses should be rated with a sufficient AIC to interrupt the highest possible load.

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.

A collection of photovoltaic modules electrically wired together in one structure to produce a specific amount of power.

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.

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).

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 Density
The ratio of the energy available from a battery to its volume (wh/m^3) or weight (wh/kg).

Friction Head
The energy that must be overcome by the pump to offset the friction losses of the water moving through a pipe.

High Voltage Disconnect Hysteresis
The voltage difference between the high voltage disconnect set point and the voltage at which the full PV array current will be reapplied.

The amount of energy in sunlight reaching an area. Usually expressed in watts per square meter (W/m2), but also expressed on a daily basis as watts per square meter per day (W/m2/day).

Any device or appliance in an electrical circuit that uses power, such as a light bulb.

Low Voltage Disconnect Hysteresis
The voltage difference between the low voltages disconnect set point and the voltage at which the load will be reconnected.

Low Voltage Warning
A warning buzzer or light that indicates the low battery voltage set point has been reached.

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.

Outgas (gassing)
Gas by-products, primarily hydrogen, produced when charging a battery. Also, termed out-gassing.

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.

An instrument used for measuring direct beams of solar irradiance. Uses an aperture of 5.7 deg. to transcribe the solar disc.

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.

Solar Insolation (Insolation)
The solar radiation incident on an area over time. Equivalent to energy and usually expressed in kilowatt-hours per square meter.