Trilig Energy

Solar Glossary

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a:Si Amorphous silicon. Silicon material having no definite or regular crystal structure.
Absorber Layers used to absorb light.
Activation voltage The voltage at which the controller will operate to protect the batteries.
Alternating current (AC) Electrical current that continually reverses direction of flow. The frequency at which it reverses is measured in cycles-per-second, or Hertz (Hz). The magnitude of the current itself is measured in amps (A).
Ammeter A device used for measuring current flow at any point in an electrical circuit.
Amorphous silicon 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.
Amp hour The quantity of electrical energy corresponding to the flow of current of one ampere for one hour. The term is used to quantify the energy stored in a battery. Most batteries are rated in Ah.
Ampere (A) or amp The unit for the electric current; the flow of electrons. One amp is 1 coulomb passing in one second. One amp is produced by an electric force of 1 volt acting across a resistance of 1 ohm.
Angle of incidence Angle between the normal to a surface and the direction of incident radiation; applies to the aperture plane of a solar panel. Only minor reductions in power output within plus/minus 15 degrees.
Anti-reflection coating A thin coating of a material with a specific refractive index applied to a cell to reduce the reflection of light.
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.
Azimuth The angle between the north direction and the projection of the surface normal into the horizontal plane; measured clockwise from north. As applied to the PV array, 180 degree azimuth means the array faces due south.
Balance of System Those components other than the PV module that compose the complete PV operating system, including the inverter (in a grid-connected system), array mounting structure, cables and connectors. Off-grid systems include a charge controller and battery for electricity storage.
Battery A system in which stored chemical energy is converted directly into electrical energy. Can be either rechargeable or non-rechargeable. Different from a fuel cell in that it contains a fixed quantity of stored chemical energy rather than a continuous supply of fuel.
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. For lead-acid batteries the voltage of a cell (fully charged) is about 2.2 volts DC. A battery may consist of a number of cells.
Battery charger A device used to charge a battery by converting usually AC voltage to a DC voltage suitable for the battery. Chargers often incorporate some form of regulator to prevent overcharging and damage to the battery.
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.
CapEx Capital Expenditure. Broadly includes all costs relating to a fab build-out, including plant and infrastructure, in addition to the tooling costs (equipment spending).
Cell The basic unit of a PV module or battery. It contains the necessary materials, such as electrodes and electrolyte in a battery, to produce electricity.
Cell efficiency The ratio of the electrical energy produced by a photovoltaic cell (under full sun conditions or 1 kw/max2 ) to the energy from sunlight falling upon the photovoltaic cell.
Charge controller A component 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 batteries obtain maximum state of charge and longest life. The charge controller may also monitor system performance and provide system protection. Charge controllers are also sometimes called regulators.
Crystalline silicon A type of PV cell material made from a single crystal or polycrystalline ingot of silicon.
Current Current is the flow of electric charge in a conductor between two points having a difference in electrical potential (voltage) and is measured in Amps.
Current at maximum power (Imp) The current at which maximum power is available from a module. [UL 1703].
Cut-off voltage The voltage levels at which the charge controller (regulator) disconnects the PV array from the battery, or the load from the battery.
Cycle The discharge and recharge of a battery.
Cycle life Number of charge-discharge cycles a battery can perform under specified conditions before it fails to meet its specified performance (e.g. capacity decreases to 80% of nominal capacity).
Days of storage The number of days that a stand-alone system will power a specified load without solar energy input. A measure of system autonomy.
DC to DC converter Electronic circuit to convert DC voltages such as PV module voltages into other levels such as load voltage. Can be part of a maximum power point tracker (MPPT).
Deep cycle battery A battery designed to regularly discharge 80% of its capacity before recharging.
Direct current (DC) Electrical current that flows only in one direction, although it may vary in magnitude. Contrasts with alternating current.
Discharge Withdrawal of electrical energy from a battery.
Earth Refers to physically connecting a part of an electrical system to the ground by means of a conductor embedded in suitable soil. Done as a safety measure.
Earth-leakage circuit breaker (ELCB) A device used to prevent electrical shock hazards in mains voltage power systems, including independent power systems. Also known as residual current devices (RCDs).
Efficiency The ratio of output power or energy to input power or energy, expressed as a percentage.
Electric circuit A Path followed by electrons from a power source (generator or battery) through an external line (including devices that use the electricity) and returning through another line to the source.
Electric current The flow of electrons measured in Amps.
Electricity The movement of electrons (a sub-atomic particle), produced by a voltage, through a conductor.
Energy Power consumed multiplied by the duration of use. For example, 1000 Watts used for four hours is 4000 Watt hours.
Fixed tilt array A solar PV array set at a fixed angle to the horizontal.
Fluorescent light A form of lighting that uses long thin tubes of glass which contain mercury vapor and various phosphor powders (chemicals based on phosphorus) to produce white light. Generally considered to be the most efficient form of home lighting.
Fuel cell An electrochemical device that converts the energy of a fuel directly into electricity and heat and is therefore very energy efficient.
Fuse A device used to protect electrical equipment from short circuits. Fuses are made with metals that are designed to melt when the current passing through them is high enough. When the fuse melts, the electrical connection is broken, interrupting power to the circuit or device.
Gassing Gaseous by-products when charging a battery, e.g. hydrogen from a lead acid battery.
Gigawatt (GW) A measurement of power equal to a thousand million Watts.
Gigawatt-hour (GWh) A measurement of energy. One Gigawatt-hour is equal to one Gigawatt being used for a period of one hour, or one Megawatt being used for 1000 hours.
Grid An electrical utility distribution network.
Grid-connected An energy producing system connected to the utility transmission grid. Also called Grid-tied.
Halogen lamp A special type of incandescent globe made of quartz glass and a tungsten filament, enabling it to run at a much higher temperature than a conventional incandescent globe. Efficiency is better than a normal incandescent, but not as good as a fluorescent light.
Hot spot A phenomenon where one or more cells within a PV module or array act as a resistive load, resulting in local overheating or melting of the cells.
Hybrid system A PV system that includes solar PV and some other electricity generating power source.
Incident light Light that shines on to the surface of a PV cell or module.
Independent power system A power generation system that is independent of the mains grid.
Insolation The amount of sunlight reaching an area, usually expressed in Watt hours per square meter per day.
Inverter An inverter converts DC power from the PV array/battery to AC power. Used either for stand-alone systems or grid-connected systems.
Irradiance The solar power incident on a surface, usually expressed in kilowatts per square meter. Irradiance multiplied by time gives insolation.
Junction box A protective enclosure on a PV module where PV strings are electrically connected and where electrical protection devices such as diodes can be fitted.
Junction diode A semiconductor device, having a junction and a built-in potential, that passes current better in one direction than the other. All solar cells are junction diodes.
Kilowatt(kW) A unit of electrical power equal to 1000 Watts.
Kilowatt-hour (kWh) A unit that describes the amount of energy that derives from a power of 1000 Watts acting over a period of 1 hour. 1 kWh equals 3600 kJ.
kWh Output Estimated first year kilowatt hour output of the PV system. Often the output on which the PPA price is paid.
Lead-acid battery A type of battery that consists of plates made of lead, lead-antimony, or lead-calcium and lead-oxide, surrounded by a sulfuric acid electrolyte. The most common type of battery used in RAPS systems.
Light emitting diode A semi-conductor device composed of a p-n junction designed such that electrons emit visible light during their migration across the junction.
Load The electrical power being consumed at any given moment or averaged over a specified period. The load that an electric generating system supplies varies greatly with time of day and to some extent season of year. In an electrical circuit, the load is any device or appliance that is using power.
mc-Si Multi-crystalline silicon.
Megawatt (MW) A measurement of power equal to one million Watts.
Megawatt-hour (MWh) A measurement of power with respect to time (i.e. energy). One megawatt-hour is equal to one megawatt being used for a period of one hour, or one kilowatt being used for 1000 hours.
Module An encapsulated panel containing a number of electrically connected PV cells.
Module de-rating factor A factor that lowers the power output of a module to account for field operating conditions e.g. dirt build-up on the module.
Monocrystalline solar cell A form of solar cell made from a thin slice of a single large crystal of silicon.
N-type semiconductor A semiconductor produced by the doping of an intrinsic semiconductor with an electron-donor impurity; for example, phosphorous in silicon.
N-Type silicon Silicon doped with an element that has more electrons in its atomic structure than does
Noise Unwanted electrical signals produced by electric motors and other machines that can cause circuits and appliances to malfunction.
Nominal voltage A rounded voltage value used to describe batteries, modules, or systems based on their specification (e.g. a 12V, 24V or 48V battery, module, or system).
Off-grid applications use independent, or stand-alone, power generation systems, normally with a form of storage such as batteries, to provide a continuous power capability. They include rural applications where the system may power lighting, TV and radio, and industrial applications such as telecommunications, navigation aids and cathodic protection systems.
Operating point Defined by the current and voltage that a module or array produces when connected to a load. It is dependent on the load or the batteries connected to the output terminals.
Orientation Position with respect to the cardinal directions of north, south, east, west.
Overcharge Applying current to a fully charged battery, which can damage the battery.
Panel Used interchangeably with "module".
Parallel connected A method of connection in which positive terminals are connected together and negative terminals are connected together. Current output adds and voltage remains the same.
Photon Light is composed of energy particles called photons which have variable energy but constant speed.
Photovoltaic (PV) Any device which produces free electrons when exposed to light.
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 electrical energy to produce a DC current and voltage.
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 consist of many crystals, compared to single crystal silicon.
Power The rate of doing work. Expressed as Watts (W). For example, a generator rated at 800 watts can provide that amount of power continuously. 1 Watt = 1 joule/sec.
PV array Two or more photovoltaic panels wired in series and or parallel.
Qualification test (PV) A testing procedure for PV modules relating to electrical, mechanical, or thermal stress.
Quasi sine-wave A description of the type of waveform produced by some inverters.
RAPS (Remote Area Power Supply) A power generation system used to provide electricity to remote and rural homes, usually incorporating power generated from renewable sources such as solar panels and wind generators, as well as non-renewable sources such as petrol-powered generators.
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.
Rated module current (A) The current output of a PV module measured under standard test conditions of 1000 W/m2 and 25.
Rechargeable battery A type of battery that uses a reversible chemical reaction to produce electricity, allowing it to be reused many times. The chemical reaction is reversed by forcing electricity through the battery in the opposite direction to normal discharge.
Rectifier A device that converts alternating current to direct current, as in a battery charger or converter.
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.
Sine wave A waveform that is defined by an equation in which one variable is proportional to the sine of the other, as generated by an oscillator in simple harmonic motion. The sine wave is the most ideal form of electricity for running more sensitive appliances, such as radios, TVs, computers and the like.
Sine wave inverter An inverter that produces grid-quality, sine wave AC electricity.
Solar constant The power density of solar radiation on a plane perpendicular to the direction of the sun at the mean earth-sun distance outside the earth's atmosphere; its value is 1.37 kW per square meter.
Solar energy Energy from the sun.
Solar module A device used to convert light from the sun directly into DC electricity by using the photovoltaic effect. Usually made of multiple solar cells bonded between glass and a backing material. A typical solar module has 100 Watts of power output (but module powers can range from 1 Watt to 300 Watts) and dimensions of 2 feet by 4 feet.
Solar power Electricity generated by conversion of sunlight, either directly through the use of photovoltaic panels, or indirectly through solar-thermal processes.
Solar thermal A form of power generation using concentrated sunlight to heat water or other fluid that may then used to drive a motor or turbine.
Tilt angle The angle of inclination of a solar collector or solar module measured from the horizontal.
Total AC load demand The sum of the AC loads; its value is used to select the correct inverter.
Tracker Any device used to direct a PV array towards the sun.
Tracking array A PV array that is moved to follow the path of the sun in order to maintain the maximum incident solar radiation on its surface. The two most common methods are single-axis tracking in which the array tracks the sun from east to west, and two-axis tracking in which the array points directly at the sun all the time. Two-axis tracking arrays capture the maximum possible daily energy. Typically, a single axis tracker will give 15% to 25% more power per day, and dual axis tracking will add a further 5%.
Transformer A device that changes voltage from one level to another. Used to transform voltage levels to facilitate the transfer of power from the generating plant to the customer.
Uninterruptible power supply (UPS) A power supply capable of providing continuous uninterruptible service; normally containing batteries to provide energy storage.
Utility-interactive inverter An inverter that can operate only when connected to the utility grid supply and an output voltage frequency fully synchronized with the utility power.
Volt The unit of electric potential and potential difference. The amount of work done per unit charge in moving a charge from one place to another. The potential difference across a resistance of 1 Ohm when a current of 1 Amp is flowing.
Voltage Unit of measurement for the electrical pressure of electricity. Measured in Volts (V).
Voltage drop The voltage lost along a length of wire or conductor due to the resistance of that conductor. Also applies to resistors. The voltage drop is calculated by using Ohm's Law.
Voltage regulator A device that controls the operating voltage of a photovoltaic array.
Voltmeter An electrical or electronic device used to measure voltage.
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) The unit of electrical power commonly used to define the electricity consumption of an appliance. The power developed when a current of one ampere flows
Watt hour (Wh) A unit of energy equal to one Watt of power being used for one hour.
Zenith angle The angle between directly overhead and a line through the sun. The elevation angle of the sun above the horizon is 90.
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