There are many reasons a homeowner, school, or business would want to install solar panels; to save money, safety, energy independence, the environment. Whatever your reason, the use of industry “jargon” or “lingo” shouldn’t be a speed bump in the process. Some solar energy terminology is self-explanatory, while others may be confusing to those without an engineering degree. To help you understand the process as much as possible, here is a useful solar energy glossary of commonly used words related to solar energy you might hear on the road to energy independence.
Solar Energy Glossary
Alternating Current (A.C.) – Type of electrical current, the direction of which is reversed at regular intervals or cycles.
Annual Solar Savings — Annual solar savings of a solar building relative to a non-solar building’s energy requirements.
Ampere-hour (Ah/A.H.) — Used to measure battery capacity, measuring the flow of current (in amperes) over one hour.
Ampere hour meter — Instrument that monitors the electrical current in time. See “ampere-hour.”
Angle of incidence — Angle that a ray of sun makes with a line perpendicular to the surface.
Array current — Electrical current produced by a solar array when exposed to sunlight.
Array operating voltage — Voltage produced by a solar array when exposed to sunlight and connected to an active system.
Balance of system — Represents all components and costs other than the solar array, including design costs, land, site preparation, system installation, support structures, power conditioning, operation and maintenance fees, indirect storage, and related expenses.
Base load — Average amount of electric power that a utility must supply in any period.
Battery available capacity — Total maximum charge, available to be withdrawn from a battery under a specific set of operating conditions.
Battery capacity — Maximum total electrical charge, which a battery can deliver to a load under a specific set of conditions.
Battery life — Period during which a cell or battery can operate above an efficiency performance level, measured in cycles or years.
British thermal unit (Btu) — Amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.
Building integrated photovoltaics — Term for the design and integration of solar technology when replacing conventional building materials.
Bypass diode — Diode connected across several solar cells, protecting the solar cells from thermal destruction in case of total or partial shading of some cells while other cells are fully exposed to light.
Charge — Process of adding electrical energy to a battery.
Charge controller — Component of a system that controls the flow of current to and from the battery to protect it from over-charge and over-discharge.
Conductor — The material through which electricity is transmitted, such as an electrical wire.
Converter — A unit that converts a direct current (dc) voltage to another dc voltage.
Current at maximum power (Imp) — Current at which maximum power is available from a system.
Days of storage — Number of consecutive days a “stand-alone system” will meet a set load without solar input. It is also related to “system availability.”
Deep-cycle battery — A battery with large plates that can withstand many discharges to a low state-of-charge.
Direct current (D.C.) — A type of electricity transmission and distribution by which electricity flows in one direction through the conductor, usually relatively low voltage and high current. Used for typical 120-volt or 220-volt household appliances.
Discharge — Withdrawal of electrical energy from a battery.
Discharge rate — Rate that is usually expressed in amperes or time, at which electrical current is drawn from a battery.
Disconnect — Switch used to connect or disconnect components in a photovoltaic system.
Distributed systems — A residential photovoltaic system that is installed at or near the location where the electricity is used. Opposed to a “central system” that supplies electricity to a grid.
Downtime — Time when the system cannot provide power towards the load.
Electric circuit — Path followed from a power source (generator or battery), through an electrical system, and returning to the source.
Electric current — Flow of electricity in a conductor.
Electrical grid — Integrated system of electricity distribution, usually covering a large area.
Electricity — Energy resulting from the flow of charge particles, such as electrons or ions.
Electrode — Conductor that is brought in conducting contact with a ground.
Energy audit — Survey showing energy usage in a home, helping find ways to consume less energy.
Fixed tilt array — A solar array set in at a fixed angle with respect to the horizontal.
Flat-plate array — A photovoltaic (P.V.) array that consists of non-concentrating P.V. modules.
Flat-plate module — A solar cell system mounted on a rigid flat surface exposed freely to incoming sunlight.
Flat-plate photovoltaics (P.V.) — An array or module that consists of non-concentrating elements. Flat-plate arrays and modules using direct and diffused sunlight, some portion of the direct sunlight may be lost because of sun-angles in relation to the array.
Federal Tax Credit — There’s currently (2021) a 26% federal tax credit for installing a home solar system. Initially set to expire at the end of 2021, an extension was included in the COVID bill passed on December 21, 2020. Meaning solar customers will continue to receive a credit (not a deduction) of 26% of the total cost for installing solar panels through 2022. In 2023, the credit drops to 22%, expiring at the end of that year. It is essential to do your research and consult a tax professional to accurately file any tax credits.
Gigawatt (G.W.) — Unit of power equal to 1 billion Watts; 1 million kilowatts, or 1,000 megawatts.
Grid-connected system or grid-interactive system— Solar electric or photovoltaic (P.V.) system in which it acts like a central generating plant, supplying power to the grid.
Hybrid system — Solar electric system that includes other sources of electricity, generated by systems like wind or generators.
Input voltage — Determines the total power required by the alternating current (A.C.) loads and the voltage of any direct current (D.C.) loads.
Interconnect — A means of connection, such as a conductor within a module, providing an electrical interconnection between the solar cells.
Inverter — Device that converts direct current (D.C.) to alternating current (A.C.).
Irradiance — The direct, diffuse, and reflected solar radiation that strikes a surface — regularly expressed in kilowatts per square meter.
Junction box — An enclosure on the module where P.V. strings are electrically connected and where protection devices can be located, if necessary.
Kilowatt (kW) — A standard unit of electrical power equal to 1000 watts, or to the energy consumption at a rate of 1000 joules per second.
Kilowatt-hour (kWh) — 1,000 thousand watts acting over a period of 1 hour. The kWh is a unit of energy — 1 kWh=3600 kJ.
Load — The demand on an energy-producing system; the energy consumption or requirement of a piece or group of equipment.
Megawatt (M.W.) — 1,000 kilowatts, or 1 million watts; a standard measure of electric power plant generating capacity.
Megawatt-hour — 1,000 kilowatt-hours or 1 million watt-hours.
Module — A single solar panel
Net Metering — A system allowing users with a solar array to send surplus or unused solar energy back to the utility grid for other users to consume.
Peak demand/load — Maximum energy demand or load in a specified period of time.
Peak sun hours — Equivalent number of hours per day when solar irradiance averages 1,000 w/m2.
Photovoltaic (s) (P.V.) — The direct conversion of light into electricity.
Photovoltaic (P.V.) array — An interconnected system of P.V. modules functioning as a single electricity-producing unit.
Photovoltaic (P.V.) cell or solar cell — Smallest semiconductor element within a P.V. module performing the immediate conversion of light into electrical energy.
Photovoltaic (P.V.) module or panel — Smallest environmentally protected, essentially planar assembly of solar cells and ancillary parts.
Photovoltaic (P.V.) system — Complete set of components for converting sunlight into electricity by the photovoltaic process. Including the array and balance of system components.
Smart grid — An intelligent electric power system regulating the two-way flow of electricity and information between power plants and consumers to control grid activity.
Soft costs — Non-hardware costs related to the installation of a solar system. Including financing, permitting, installation, interconnection, and inspection.
System availability — Percentage of time (usually expressed in hours per year) when a solar system will be capable of fully meeting the load demand.
Tilt angle — Angle at which a photovoltaic array is oriented to face the sun relative to a horizontal position. This can be adjusted to maximize seasonal or annual energy collection.
Volt (V) — Unit of electrical force equal to that amount of electromotive force that will cause a steady current of one ampere to flow through a resistance of one ohm.
Voltage — Amount of electromotive force, measured in volts, that exists between two points.
Voltage at maximum power (Vmp) — The voltage at which maximum power is available from a photovoltaic module.
Watt — Rate of energy transfer equivalent to one ampere under an electrical pressure of one volt. One watt equals 1/746 horsepower or one joule per second. It is the product of voltage and current (amperage).
Hopefully, our solar energy glossary and the list of solar system terminology has been informative. However, the best way to get educated is to contact a solar professional, making sure to ask questions. As professionals, it is their duty to answer your questions and guide you through your energy independence journey.
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