Glossary
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AGM (Absorbed Glass Mat):
Type of battery construction that uses saturated absorbent glass mats rather than gelled or liquid electrolyte resulting in enhanced reliability.
Amorphous:
A thin-film solar PV cell material which has a glassy rather than crystalline structure. Made by depositing layers of doped silicon on a substrate normally using plasma-enhanced chemical vapor deposition of silane.
Array:
A number of solar modules connected together in a single structure.
Array current:
The electrical current output of a PV array when exposed to sunlight.
Array Operating Voltage:
The voltage output of a PV array when exposed to sunlight and feeding a load.
Availability:
The quality or condition of a PV system that is available to provide power to a load. Usually measured in hours per year.
Battery:
A system in which stored chemical energy is converted directly into electrical energy.
Battery capacity:
The total number of ampere-hours (Ah) that a fully charged battery can output.
Battery cell:
An individual unit of a battery that can store electrical energy and is capable of furnishing a current to an external load. A battery may consist of a number of cells.
Battery cycle life:
The number of times a battery can undergo a cycle of discharge and recharge before failing. Cycle life is normally specified as a function of discharge rate and temperature.
Capacitor:
An electronic component used for the temporary storage of electricity , as well as removing unwanted noise in circuits.
Cell Efficiency:
The ratio of the electrical energy produced by a photovoltaic cell (under full sun conditions or 1kW/m2) to the energy from the sunlight falling upon the photovoltaic cell.
Cell:
The basic unit of a PV module or battery. The most basic unit that contains the necessary materials, such as electrodes and electrolyte in a battery, to produce electricity.
Charge:
The process of inputting electrical energy to a battery
Charge controller:
A circuit that controls the flow of current to and from the battery subsystem to protect the batteries from overcharge and over discharge. Essential for ensuring that the batteries obtain maximum state of charge and longest life. The charge controller also monitors system performance and provides system protection.
Charge rate:
A measure of current used to charge a battery as a proportion of itscapacity.
Circuit:
A continuous system of conductors providing a path for electricity.
Circuit breaker:
A circuit breaker acts like an automatic switch that can shut the power off when it senses too much current.
Conductor:
A material used to transfer or conduct electricity often in the form of wires.
Cut-off voltage:
The voltage levels at which the charge controller (regulator) disconnects the PV array from the battery of the load from the battery.
Cycle:
The discharge and re-charge of a battery, one complete charge/discharge cycle of the battery.
Days of storage:
The number of days that a stand-alone system will power a specified load without solar energy input.
Diode:
Electronic device that allows current flow only in one direction.
Discharge:
Withdrawal of electrical energy from a battery
ECU:
Electronic Control Unit
Efficiency:
The ratio of output power or energy to input power or energy, expressed as a percentage.
Electric current:
The flow of electrons measured in Amps.
Electrical grid:
A network for electricity distribution across a large area.
Electricity:
The movement of electrons (a sub-atomic particle), produced by voltage, through a conductor.
EMS:
(Energy management system) The software within the ECU which reduces output power when the input power from the sun is low.
Energy:
Power consumed multiplied by the duration of use.
Fuel cell:
An electrochemical device that converts the energy of a fuel directly into electricity and is therefore very energy efficient.
Fuse:
A fuse is a device used to protect electrical equipment from short circuits.
Gel-type battery:
Lead-acid battery in which the electrolyte is suspended in a gel.
Grid:
An electrical utility distribution network.
High voltage disconnect:
Voltage at which the charge controller will disconnect the array to prevent overcharging the batteries.
Hybrid system:
A PV system that includes solar PV and some other electricity generating power source.
Integrator:
Integrates PV components in to a complete PV system.
Light Emitting Diodes(LED’s):
A semiconductor device composed of a p-n junction designed such that electrons emit visible light during their migration across the junction.
Loom/Harness:
The wiring configuration
Low voltage disconnect:
(LVD) The voltage at which the charge controller will disconnect the load from the batteries to prevent over over-discharging.
Module:
An encapsulated panel containing a number of electrically connected PV cells.
Monocrystalline solar cell:
A form of solar cell made from a thin slice of a single large crystal of silicon.
Multicrystalline:
A material that has solidified at a rate such that many small crystals (crystallites) form. The atoms within a single crystallite are symmetrically arranged with a particular orientation, whereas the crystallites themselves are differently orientated. The multitude of grain boundaries in the material ( between the crystallites) reduce the cell efficiency. Multicrystalline is also referred to as polycrystalline.
Ohm:
The resistance between two points of a conductor when a constant potential difference of one volt applied between these points produces in the conductor a current of one Amp.
Peak load:
The maximum usage of electrical power occurring in a given period of time, typically a day.
Photon:
Light is composed of energy particles called photons which have variable energy but constant speed.
Photovoltaic (PV) array:
A number of PV modules connected together in a single structure.
Photovoltaic (PV) cell:
The smallest discrete element in a PV module that performs the conversion of light into an electrical energy to produce a DC current and voltage.
Photovoltaic ( PV) module:
A single assembly of solar cells and ancillary parts such as interconnections, terminals and protective devices intended to generate DC power in un-concentrated sunlight.
Photovoltaic (PV) panel:
A term used interchangeably with PV module.
Photovoltaic(PV) Refers to any device which produces free electrons when exposed to light.
Photovoltaic system:
All the parts connected together that are required to produce solar electricity.
Photovoltaic cell:
The semiconductor device that converts solar irradiance (light) into DC electricity.
Photovoltaic effect:
The effect that causes a voltage to be developed across the junction of two different materials when they are exposed to light.
Polycrystalline cell:
A wafer of silicon with a multi-grained structure. All grains have the same atomic crystal lattice, however, each grain has a unique orientation in space thereby producing a unique reflection of light.
Polycrystalline silicon:
A material used to make solar PV cells which consists of many crystals, compared to single crystal silicon.
Potting:
The material used to cover all electronic componentry to ensure water does not cause damage.
PV array:
Two or more photovoltaic panels wired in series and or parallel.
PV:
Short hand for Photovoltaics.
PV components:
The individual parts of a PV System. Individual items like Batteries, Inverters, Regulators, Wiring looms. PV system: All the parts in combination required to generate solar electricity.
Quiescent current:
The amount of power consumed by the ECU when it is idle.
Rated battery capacity (Ah):
Term used by battery manufacturers to indicate the maximum amount of energy that can be withdrawn from a battery at a specified discharge rate and temperature.
Rectifier:
A device that converts ac to dc, as in a battery charger or converter.
Regulator:
A device used to limit the current and voltage in a circuit, normally to allow the correct charging of batteries from power sources such as solar panels and wind generators
Remote site:
A site with no electrical utility grid connection.
Renewable energy:
Energy that is produced from a renewable source
Resistance (R):
The property of a material which resists the flow of electric current when a potential difference is applied across it, measured in Ohms.
Resistor:
An electronic component used to restrict the flow of current in a circuit. Sometimes used specifically to produce heat, such as in a water heater element.
Semiconductor:
A material that has an electrical conductivity in between that of a metal and an insulator. Transistors and other electronic devices are made from semiconducting materials, and are often called semiconductors. Typical semiconductors for PV cells include silicon, gallium arsenide, copper indium diselenide, and cadmium telluride.
Silicon (Si):
A chemical element with atomic number 14, a dark gray semi-metal. Occurs in a wide range of silicate minerals and makes up approximately 28% of the earth's crust (by weight). Silicon has a face-centered cubic lattice structure like diamond. The most common semiconductor material used in making PV cells either traditionally in its crystalline form or more recently as an amorphous thin film.
Single-crystal silicon:
Silicon material with a single crystal structure. A common material for the construction of solar PV cells.
Solar energy:
Energy from the sun.
Solar power:
Electricity generated by conversion of sunlight, either directly through the use of photovoltaic panels, or indirectly through solar-thermal processes.
Solar module:
A device used to convert light from the sun directly into DC electricity by using the photovoltaic effect.
Stand-alone (PV system):
A solar PV system that operates without connection to a grid a supply of electricity.
String:
A number of cells, modules or panels interconnected electrically in series to produce the required operating voltage.
Substrate:
The physical material upon which a photovoltaic cell is made. Sub-system: Any one of several components in a PV system (i.e., array, controller, batteries, inverter, load).
Superstrate:
The covering on the sun side of a PV module, providing protection for the PV materials from impact and environmental degradation while allowing maximum transmission of the appropriate wavelengths of the solar spectrum.
System availability:
The proportion of time (usually expressed in hours per year) that a solar PV system will be able to fully meet the load demand.
Temperature compensation:
Adjustment via the use of electronic circuitry to change the charge controller activation points depending on battery temperature.
Thick cells:
Conventional solar cells in most types of PV modules, such as crystalline silicon cells, which are typically from 200-400 micrometers thick. In contrast, thin-film cells are several microns thick.
Thin film PV module:
A solar PV module constructed with sequential layers of thin film semiconductor materials usually only micrometers thick.
Uninterruptible power supply (UPS):
A power supply capable of providing continuous uninterruptible service; normally containing batteries to provide energy storage.
Voltage regulator:
A device that controls the operating voltage of a photovoltaic array.
Voltage:
Unit of measurement for the electrical `pressure' of electricity. Measured in Volts (V).
Wafer:
A thin sheet of crystalline semiconductor material either made by mechanically sawing it from a single-crystal boule or multicrystalline ingot or block, or made directly by casting. The wafer is "raw material" for the solar cell.
Watt (W):
Hybrid system
The unit of electrical power commonly used to define the electricity consumption of an appliance.
