Glossary
AEC
Alternative Energy Certificate. A digital certificate
certifying production of 1,000 kilowatt-hours (kWh), or 1 megawatt-hours (MWh)
of clean solar electricity. These are tradable, selling on an open market, with prices
varying depending on the state in which you live.
Alternating Current (AC)
A type of electrical current,
the direction of which is reversed at regular intervals or cycles. In the United
States, the standard is 120 reversals or 60 cycles per second. Electricity
transmission networks use AC because voltage can be controlled with relative
ease.
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, which is done by an inverter.
Federal Investment Tax Credit (FITC)
Established by the
federal Energy Policy Act of 2005 and enhanced in February 2009 by The American
Recovery and Reinvestment Act of 2009, allows businesses and homeowners a tax
credit equal to 30% of the total installed cost of a solar electric or thermal
system. The credit can be carried forward until with no maximum credit.
Grid-tied
A solar electric or thermal system which is
connected to a utility grid, allowing it to send excess energy into the grid.
Grid-tied systems are desirable whenever utility lines are available, as it
allows you to reduce costs by selling power back to the grid and pulling power
from it when needed.
Heat Exchanger
Found in closed loop Solar Hot Water
systems, they allow the transfer of heat from one fluid to another without the
two mixing.
Inverter
A device that converts direct current
electricity to alternating current either for stand-alone systems or to supply
power to an electricity grid.
Kilowatt (kW)
A standard unit of electrical power equal
to 1000 watts,
Kilowatt-Hour (kWh)
1,000 watts acting over a
period of 1 hour.
Net metering
A billing arrangement by which you as a
generator of electricity receive utility bill credit for electricity generated
but not used on site. The unconsumed or excess power is sent back to the utility
grid and credited to your next bill at the full retail rate.
Photovoltaic (PV)
The direct conversion of light into
electricity.
Photovoltaic Array
An interconnected system of PV modules
that function as a single electricity-producing unit.
Photovoltaic Module
A discrete assembly of photovoltaic
cells which make up a PV system. These are generally 3 ft x 5 ft and weigh 40
pounds. PV modules are mounted on a roof, pole, or the ground and convert the
sun’s energy into DC power.
Solar Thermal Collectors
A solar collector gathers and
stores the sun’s energy via a network of pipes through which water or
anti-freeze is heated. Flat plate collectors are the most common type; they
consist of copper tubes fitted to a flat absorber plate. Evacuated tube
collectors are more efficient, working best in cold, cloudy climates.
