G

GASSING The production of hydrogen and oxygen gas from one or more of the electrodes in the cells of a battery. Gassing commonly results from the electrolysis of water in the electrolyte during charging.

GENERATOR A device that converts mechanical energy into electrical energy.

GEOTHERMAL HEAT PUMP A type of heat pump that uses the ground, ground water, or ponds as a heat source and heat sink, rather than outside air. Compare to HEAT PUMP.

GIN POLE Either of two different types of devices used with wind generator towers. With a tilt-up tower, it describes the lever that helps tilt the tower up. With a fixed tower, it describes a temporary crane used to raise tower sections or the wind generator.

GLYCOL (Propylene Glycol) An antifreeze, heat transfer fluid that is circulated through closed loop solar hot water collectors.

GOVERNOR A device that limits the output of another device, such as a wind generator.

GOVERNING Limiting the output of a device. In respect to small wind generators, governing normally happens through furling.

GRID Transmission line network used to distribute electrical energy, generally by a commercial power utility.

GRID LINES Metallic contacts fused to the surface of a solar cell to provide a low resistance path for electrons to flow out to the cell interconnect wires.

GRID-TIE SYSTEM A renewable energy system that is connected to the utility grid, selling excess energy back to the utility. Also called a utility-interactive system.

GROUND The connection of electrical components to the earth and/or each other for the purposes of dissipating static charge or protecting against a short circuit or lightning.

GROUND FAULT Unwanted current path to ground.

GROUND MOUNT A photovoltaic (PV) rack designed to be installed on the ground or other flat surface.

GROUND ROD (ELECTRODE) A metal rod (typically 5/8 inch diameter) that is driven into the earth (typically 8 feet deep) and is electrically connected to the negative conductor and/or any metal parts, wiring enclosures, or conduit of an electrical circuit.

GUY WIRES Steel cables that support a tower.