Solar Power: Commonly used technical terms
Absorption Coefficient – The ratio at which photons are absorbed over unit of distance as they travel through material with photovoltaic properties (e.g. silicon)
Alternating Current – AC current – Electric current in which the direction of electron flow is reversed at intervals (frequency). AC electricity is used in most household appliances and the electricity grid.
AM – Airmass – a unit of atmospheric mass measurement commonly used in discussion of rating solar photovoltaic panels. The AM measurement for photovoltaic solar panels at standard test conditions (STC) is 1.5AM.
Amorphous silicon – Amorphous semiconductor – Thin-film, non-crystalline semiconductor material that can be used in the production of solar electricity via the photovoltaic effect.
Ampere – A – A measure of electric current (compare: power (W) and volt (V)).
Ampere hour – Ah – A unit of electrical charge stored in a battery. 1Ah equals the flow of 1A of current for one hour.
Antireflection Coating – A thin coating over a photovoltaic cell that improves light transmission onto the cell, and reduces the amount of reflection of light off the cell.
Array – A number of solar photovoltaic (PV) panels connected together, usually all feeding into one solar inverter.
Azimuth – Horizontal angle measured clockwise from true north with 180 degrees being true south.
Balance of System (BoS) – all the components of a solar photovoltaic system except for the photovoltaic solar panels themselves.
Base load – When talking about power stations, the minimum amount of electricity that a power generator must supply at any given time
Battery – A device that stores electricity in chemical bonds for later discharge and use; in terms of solar power, batteries are ordinarily only used in stand-alone or off-grid solar power systems.
Building-Integrated Photovoltaics (BIPV) – Design of solar photovoltaic systems into the building envelope, taking into account whole-of-system energy efficiency and strategic passive solar and HVAC design considerations. BIPV units may replace ordinary building components, including windows, awnings, roofs, and walls.
Capacity – The measure of a solar power system’s output, usually in peak conditions. Capacity is usually measured in Watts (W) or kilowatts (kW). 1kW = 1000W. Amps x Volts = Watts.
Current – The measure of the ‘flow rate’ or ‘intensity’ of electricity, measured in Amps (A). Amps x Volts = Watts.
Direct Current (DC) – The type of electricity produced by solar panels and which comes out of batteries. The electricity grid and most household appliances use Alternating Current (AC).
Energy – As differentiated from ‘power’, energy is the ‘amount’ that you have stored to do work for you. Batteries for solar power systems store energy, not power.
Externality – The costs or benefits that are not financially accounted for in the pricing of a resource. An example of a positive externality would be the scenic value a tree planted by your neighbor that gives you shade in summer. An example of a negative externality is carbon emissions given off by the burning of fossil fuels–unless accounted for under a carbon tax or emissions trading scheme.
Feed-in Tariff – FiT – A rate paid to those who own or operate power generation systems (such as solar or wind) that feed electricity back into the electrical grid, usually to encourage the uptake of renewable energy. Feed-in Tariffs are paid for by the government, or conventional electricity retailers are required to pay a set rate to those feed electricity into the grid and are signed up for such a scheme.
Gigawatt (GW) – 100 megawatts (MW) of capacity. Germany currently has approximately 60GW of solar photovoltaics installed.
High-efficiency – An adjective used to describe the conversion of energy or power available to usable energy or power. The most efficient solar panels in the world reach just about 20% efficiency (i.e. sunlight to power). For a solar inverter, efficiency refers to the rate at which DC electricity from your panels is converted to grid-compliant AC electricity.
Heat coefficient – When solar panels get hot, they lose efficiency. A heat coefficient is the rate at which solar panel power output is reduced, and is usually measured in terms of -% per degree above 45C.
Inverter – An inverter transforms DC electricity (produced by solar panels and batteries, among other things) into AC electricity, which is what the electricity grid and most household appliances use.
Joule (J) – A measure of energy. However, in electronics the convention is to measure energy in watt-hours (Wh) or kilowatt-hours (kWh).
Kilowatt (kW) – 1000 watts
Kilowatt-hour (kWh) – 1000 watt-hours, i.e. 1kWh is how much energy you would have produced if you ran a 1000W solar system in full sunlight for 1 hour.
Large-Scale Generation Certificate (LGC) – A certificate created under the Enhanced Renewable Energy Target and issued to individuals or organizations that develop large-scale renewable energy projects, including solar PV and concentrating solar power plants. The price of an LGC (formerly known as a REC, or Renewable Energy Certificate) fluctuates with supply and demand.
Light-induced degradation (LID) – The tendencies of certain types of photovoltaic cell to lose efficiency over time due to constant insolation. Many solar panel manufacturers use anti-LID technology.
Megawatt (MW) – 1000 kilowatts (kW) of power.
Operating range, inverter – The voltage or power range within which a solar inverter functions.
Peak efficiency – The highest output efficiency level that a solar panel or a solar inverter can reach.
Photovoltaics (PV) – Technology (usually semi-conductor-based) that converts light, especially sunlight, into usable electricity.
Renewable Energy Certificate (REC) – A certificate created under the Enhanced Renewable Energy Target and issued to people who install renewable energy generators, including solar PV systems. The price of a REC (now officially known as an STC, or Small-scale Technology Certificate) fluctuates with supply and demand.
Small-Scale Technology Certificate (STC) – A certificate created under the Enhanced Renewable Energy Target and issued to people who install renewable energy generators, including solar PV systems. The price of an STC (formerly known as an REC) fluctuates with supply and demand.
Solar Power – Power generated by the sun, either through photovoltaic technology or concentrating solar power (CSP) or solar thermal
Solar Installer – A company or person who installs solar power systems
Solar photovoltaic effect – The phenomenon through which sunlight is converted to electricity via materials with photovoltaic properties
Solar Panel – A module composed of solar photovoltaic materials that turns sunlight into electricity