Renewable Energy Vocabulary: J-M

A-C • D-F • G-I • J-M • N-P • R-S • T-Z

JACK PUMP
A submerged pump mechanically activated by a rod extending above the well head to a reciprocating engine, motor or any other rotating device.

JOULE
The standard unit of energy (SI). One joule equals one watt-second, and 3600 joules = one watt-hour.

KILOWATT (KW)
One thousand watts.

KILOWATT-HOUR
One thousand watt-hours. Unit of energy used to perform work (energy and work are equivalent in units, energy being the potential value and work the achieved value).

Fuel equivalents: One barrel of crude oil contains roughly 1,700 KWH

One ton of coal contains roughly 7,500 KWH

One gallon of gasoline contains roughly 37 KWH

One cubic foot of natural gas contains 0.3 KWH

One ton of uranium ore contains 164 million KWH

1.34 horsepower-hours.

1 KWH = 3,400 BTU. Can be compared to 860 calories (food energy value).

LATITUDE
A location’s distance north or south of the equator measured in degrees.

LIGHT EMITTING DIODE (LED)
A semiconductor device composed of a PN junction designed such that electrons cause visible light during their migration across the junction.

LIGHTNING ARRESTOR
Devices that protect electronics from lightning-induced surges by carrying the charge to ground.

LINE/WIRE LOSS
The voltage drop or energy loss due to the resistance of wire in an electrical circuit. See VOLTAGE DROP

LINEAR CURRENT BOOSTER (LCB)
An electronic circuit that matches PV output directly to a motor by converting unneeded voltage to higher usable current. Used in array-direct water pumping.

LOAD
Refers to equipment that is powered by electricity. Usually expressed in terms of amperes or watts. Any device or appliance that uses energy (such as a light or pump).

LOW-E GLASS
Glass coated with layers of metal or metal oxide. The coating emits very little radiation in the long-wave (infrared) spectrum, which diminishes heat loss from the building interior, and reduces heat gain in hot weather.

LUMEN
A unit of measurement quantifying the amount of light emitted from a light source.

MAGNETIC DECLINATION
The number of degrees east or west of true south from magnetic south.

MAXIMUM POWER POINT
The point on a PV module’s voltage/amperage curve where the product of current and voltage is a maximum (measured in watts).

MAXIMUM POWER POINT TRACKING (MPPT)
Electronically tracking the maximum power point of a PV module to achieve the highest possible output, by (in simplest terms) using surplus voltage to boost amperage.

MICROHYDRO
Hydro-electric plants producing more than 100 watts and less than 2,000 watts.

MODULE
The smallest nondivisible, self-contained, and environmentally protected physical structure housing interconnected photovoltaic cells and providing a single DC electrical output. Commonly called a “panel.”

MOTOR
A device that converts electrical energy into mechanical energy.

MULTICRYSTALLINE CELL
See POLYCRYSTALLINE CELL