Glossary
of Renewable Energy and Electrical Terms
Alternating Current (AC): electricity
delivered by U.S. utilities at 60 Hz, and 120 volts.
Amp: electrical current; a measure of flowing
electrons.
Amp-hour: measure of flowing electron for
a period of time.
Audit: an energy audit seeks energy inefficiencies
and prescribes improvements.
Battery: A collection of cells that store
electrical energy; each cell converts chemical energy into electricity or vice
versa, and is interconnected with other cells to form a battery for storing useful
quantities of electricity.
BTU: British Thermal Unit, the amount of
heat required to raise the temperature of one pound of water one degree Fahrenheit;
3411 BTUs equals one kilowatt-hour.
Compact Fluorescent Light (CFL): a modern
light bulb with an integral ballast using a fraction of the electricity used by
a regular incandescent light bulb.
Direct Current (DC): the complement of
AC, or alternating current, presents one unvarying voltage to a load. This is
standard in automobiles.
Efficiency: a narrow mathematical I concept
describing the proportion of a resource that can actually be converted' into useful
product or work; for example, sunlight falling on a PV module contains a given
amount of energy, but the module can only convert a percentage of it into electricity.
Electronic Ballasts: an improvement over
core/coil ballasts used to drive fluorescent lamps.
Embodied Energy: Literally the amount of
energy required to produce an object in its present form; an inflated balloon's
embodied energy includes the energy required to manufacture it and inflate it.
Generator: any device that produces electricity.
Grid: a utility term for the network of
wires that distribute electricity from a variety of sources across a large area.
The "grid" powers most homes and offices across the country.
Heat Exchanger: device that passes heat
from one substance to another; in a solar hot water heater, for example, the heat
exchanger takes heat harvested by a fluid circulating through the solar panel
and transfers it to domestic hot water.
Hydronic: contraction of hydro and electronic,
usually applied to radiant in-floor heating systems and their sensors and pumps.
Incandescent Bulb: a light source that
produces light by heating a filament until it emits photons.
Insolation (or incident solar-radiation:
the amount of sunlight failing on a place.
Insulation: a material that keeps energy
from crossing from one place to another: on electrical wire, it is the plastic
or rubber that covers the conductor; in a building, insulation makes the walls,
floor, and roof more resistant to the outside (ambient) temperature.
Inverter: the electrical device that changes
direct current (DC) into alternating current (AC).
Kilowatt: 1000 watts.
Kilowatt/hour: one kilowatt of power used
for one hour. A typical house uses 750 kW/hrs per month.
Light Emitting Diode (light emitting diode):
An efficient source of electrical lighting, typically lasting 50,000 to 100,000
hours.
Load: an electrical device, or the amount
of power required by such a device.
Megawatt (MW): 1,000,000 watts.
Modules: the manufactured panels of photovoltaic
cells; a module typically houses thirty-six cells in an aluminum frame covered
with a glass or acrylic cover and provides a junction box for connection between
itself, other modules in the array, and the solar electric system.
Net metering: a desirable form of buy-back
agreement in which the line-tied house's electric meter turns in the utility's
favor when grid power is being drawn, and in the system owner's favor when the
house generation exceeds its needs and electricity is flowing into the grid. At
the end of the payment period, when the meter is read, the system owner pays the
utility the difference between what was used and what was produced.
"Off-the-grid": not connected
to the power lines: electric self-sufficiency.
Passively Heated: a shelter that has its
space heated by the sun without using any other energy.
Petroleum: an oily, flammable liquid composed
of a complex mixture of hydrocarbons occurring in many places in the upper strata
of the earth. A fossil fuel.
Phantom Loads: appliances that draw power
24 hours a day, even when you turn them off. TVs, VCRs, microwave ovens with clocks,
and plugs with the integrated little black box all contain phantom loads.
Photovoltaics (PVs): A technology for using
semiconductors to directly converts light into electricity.
R-value: resistance value, used specifically
for materials used for insulating structures. Three inches of fiberglass insulation
has an R-value of 11.
Renewable Energy: an energy source that
renews itself without, effort; fossil fuels, once consumed, are gone forever,
while solar energy is renewable in that the sun we harvest today has no effect
on the sun we can harvest tomorrow.
Renewables: shorthand for renewable energy
or material sources.
Sustainable: material or energy sources
that, if managed carefully, will provide at current levels indefinitely.
Volt: measure of electrical potential,
110-volt house electricity has more potential to do work than an equal flow of
12-volt electricity.
Watt: measure of power (or work) equivalent
to 1/746 of a horsepower.
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