Solar Glossary

Array — An interconnected system of photovoltaic modules that function as a single electricity-producing unit. The modules are assembled as a discrete structure, with common support or mounting.




Direct Current (DC) —  A type of electricity transmission and distribution by which electricity flows in one direction through the conductor, usually relatively low voltage and high current. To be used for typical 120 volt or 220-volt household appliances, DC must be converted to alternating current, its opposite.






Panel — often used interchangeably with PV module, but more accurately used to refer to a physically connected collection of modules.


Photovoltaic (PV) — Pertaining to the direct conversion of light into electricity.

Purchase Power Agreement–contracts between two parties, one who generates electricity for the purpose of sale (the seller) and one who is looking to purchase electricity (the buyer). There are various forms of Power Purchase Agreements; these are differentiated by the source of energy harnessed (solar, wind, etc.). Financing for the project is delineated in the contract, which also specifies relevant dates of the project coming into effect, when the project will begin commercial operation, and a termination date for which the contract may be renewed or abandoned.

Renewable Energy Resource — An energy resource that is regenerative or virtually inexhaustible. Typical examples are wind, solar, geothermal, and water.

Solar Energy — Electromagnetic energy transmitted from the sun.




Balance of System — Used to describe the AC and DC breakers, fuses and other electrical safety components of a utility or grid tied solar electric system. Components other than the solar modules, mounting structure, and inverter.

Battery Backup — The use of batteries to power your system in case of electrical power outage. Used for emergency back up only of critical loads.



Grid-Tie System (GTS) — A solar electric or photovoltaic (PV) system in which the PV array acts like a central generating plant, supplying power to the grid. Also called a Grid-Connected System.



Net Metering — The practice of exporting surplus solar power during the day (to actual power needs) to the electricity grid, which either causes the home owner electric meter to (physically) go backwards and/or simply creates a financial credit on the home owner’s electricity bill. (At night, the homeowner draws from the electricity grid in the normal way).

Rack Mounts — In a rack mount, the photovoltaic modules (solar panels) are supported by a metal framework and are set at a predetermined angle. The rack-mounted solar array is placed above the roof with the rack’s members bolted to the roof’s structural members. Pre-configured rack mounting offered with ASG Power, SunWise and other systems position the solar panels at the roof pitch angle. Additional mounting components are available if panels need to be tilted further (e.g., on flat or low-pitch roofs) in order to maximize the solar array performance. Please don’t hesitate to contact us for consultation if you have related questions.













Off-Grid System — An autonomous or hybrid photovoltaic system not connected to a grid. May or may not have storage, but most off-grid systems require batteries or some other form of storage. Also called a stand-alone system.

Parallel Connection —A way of joining solar cells, photovoltaic modules, or photovoltaic panels by connecting positive leads together and negative leads together; such a configuration increases the current, but not the voltage.





Vented Cell — A battery designed with a vent mechanism to expel gases generated during charging.Adequate Wind Resource — The wind speed you would need to start up your turbine and the average speed needed to produce power. This will vary by manufacturer and model.

Base — The structure below the generator of a wind turbine that supports the turbine, houses the meters and wires, and keeps the turbine high above the ground level to protect the surrounding area and people from the force of the blades. Also, to get the turbine above the surrounding buildings which could otherwise block the wind.

Blades — Usually flat objects connected to a center shaft that converts the push of the wind into a circular motion in a wind turbine.

Dump Load — A machine that uses excess energy being produced to heat air or water.

Free Standing Tower — A structure that is used to support a wind generator, usually high in the air with no supports.

Guyed Tower — A structure that is used to support a wind generator, usually high in the air with wires anchoring it to the ground.

Hybrid System — A system that combines wind and solar energy.

Marine Wind Turbine — A wind turbine that is designed to be used on or near water. It has a painted and sealed body and offers more protection from the elements.

Rated Power Output — Used by wind generator manufacturers to provide a baseline for measuring performance. Rated output will vary by manufacturer.

Tower Kit — Set of hardware that is used to secure the wind generator to the tower. (May or may not include tower pole depending on the brand/model.)

Wind Generator — A machine that is used to produce electricity. Often used interchangeably with wind turbine.

Wind Turbine — A machine that captures the force of the wind and converts it into electricity. Often used interchangeably with wind generator.

Booster Pump — A surface pump used to increase pressure in a water line, or to pull from a storage tank and pressurize a water system.

Centrifugal Pump — A pumping mechanism that spins water in order to push it out by means of centrifugal force.

Check Valve — A valve that allows water to flow one-way but not the other.

Diaphragm Pump — A type of pump in which water is drawn in and forced out of one or more chambers, by a flexible diaphragm. Check valves let water into and out of each chamber.

Dispositive Displacement Pump — Any mechanism that seals water in a chamber, then forces it out by reducing the volume of the chamber. Used for low volume and high lift.

Dry Run Switch — A device that stops the pump when there is no water to pump in the well.

Float Switch — An electrical switch that responds to changes in water level. It may be used to prevent overflow of a tank by turning a pump off, or to prevent a pump from running dry when the source level is low.

Float Valve — A valve that responds to changes in water level. It is used to prevent overflow of a tank by blocking the flow of water.

Foot Valve — A check valve placed in the water source below a surface pump. It prevents water from flowing back down the pipe.

Head — The vertical distance that water is pumped. This determines the pressure that the pump pushes against. Total head = vertical lift from surface of water source up to the discharge in the tank + (in a pressure system) discharge pressure. Also called vertical lift.

Helical Rotor Pump — A pump with a helix-shaped rotor that fits closely into a rubber stator that has a helical groove. It forms sealed cavities that trap water. As the rotor turns, the cavities move toward the outlet.

Impeller — The device that spins inside of a centrifugal pump, in order to develop centrifugal force.

Jet Pump — A surface-mounted centrifugal pump that uses an ejector (venturi) device to augment its suction capacity. In a deep well jet pump, the ejector is down in the well, to assist the pump in overcoming the limitations of suction.

Lift — The distance the water is to be raised.

Linear Current Booster (LCB)– An electronic device, which varies the voltage and current of a PV array to match the needs of an array-direct pump, especially a positive displacement, pump. It allows the pump to start and to run under low sun conditions without stalling. Also called pump controller.

Multi-stage Centrifugal Pump — A centrifugal pump with more than one impeller and chamber, stacked in a sequence to produce higher pressure. Conventional AC deep well submersible pumps and some solar submersibles work this way.

Pounds per Square Inch — vertical lift (head) in Feet / 2.31.

Pressure Switch — An electrical switch actuated by the pressure in a pressure tank. When the pressure drops to a low point (cut-in) it turns a pump on. At a high point (cut-out) it turns the pump off.

Priming — The process of hand-filling the suction pipe and intake of a surface pump. Priming is generally necessary when a pump must be located above the water source. A self-priming pump is able to draw some air suction in order to prime itself, at least in theory.

Pulsation Damper — A device that absorbs and releases pulsations in flow produced by a piston or diaphragm pump. Consists of a chamber with air trapped within it or a length of flexible tube.

Pump Controller — An electronic device that controls or processes the power to a pump. This devise will start and stop the pump.


Pump Jack — A deep well piston pump. The piston and cylinder is submerged in the well water and actuated by a rod inside the drop pipe, powered by a motor at the surface. This is an old-fashioned system that is still used for extremely deep wells.

Submersible Pump — A motor/pump combination that is designed to be placed entirely below the water surface.

Surface Pump —A pump that is not submersible. It must be placed no more than about 20 ft. above the surface of the water in the well.
