Glossary of Solar Terms
Array - A group of solar panels collectively makes up a solar
Grid - The network of power-lines which connects power plants to
substations and on to distribution lines which take power to homes
or businesses. It can be used to refer to a transmission-level grid
or a distribution-level grid, which have slightly different
Grid-tied (or grid-connected) system - A solar electric system in
which the array can receive power from the electric utility, and
can also supply power to the grid.
Insolation - The amount of sunlight reaching an area, usually
expressed in Watt hours per square meter per day.
Interconnection Application - The form which your electric
cooperative representative will ask you to complete. This form
initiates the process of connecting your solar PV system to the
Interconnection Agreement - The document which defines the terms
and conditions under which your system will be connected to the
utility grid, including the technical requirements necessary to
ensure safety and power quality.
Inverter - A device that converts DC power captured by the
photovoltaic cells on solar panels into AC power that can be used
to power your home or business. This device is an integral part of
a solar system. Large solar systems may have more than one
Irradiance - The solar power incident on a surface, usually
expressed in kilowatts per square meter. Irradiance multiplied by
time gives insolation.
kW (kilowatt) - A measurement of power. A kilowatt is one thousand
Watts. The size of a solar system is often measured in kW. A
typical size solar system for a home is 3-7 kW; for a medium sized
business is 10-100 kW.
kWh (kilowatt-hour) - A measurement of energy consumption or
energy generation. One kilowatt hour is defined as the amount of
energy consumed by a 1000-Watt appliance running continuously for 1
hour. This is the measurement your utility company uses to
calculate your electric bill and will be the measure of your solar
Meter - An electricity meter or energy meter is a device that
measures the amount of electric energy consumed by a residence,
business, or an electrically powered device.
Module - An encapsulated panel containing a number of electrically
connected PV cells.
Net-metering of solar electricity generation is used to calculate
the difference between energy that is used and energy that is
produced. The customer is then billed for the electricity he uses,
or receives a credit if excess electricity is produced by the solar
electric system owned by the customer.
Orientation - Position with respect to the directions of north,
south, east, west.
Panel - A group of modules arranged and attached in one plane, or
can be used interchangeably with "module".
Photovoltaic (PV) - The process of converting light into
electrical energy. A photovoltaic cell is a device which converts
light into electrical energy. The PV cells are manufactured into a
module, which is then wired into an array, and ultimately into a PV
Pyranometer - An instrument used for measuring solar
Racking - Structural supports used to hold the modules in place.
Racking is used to mount the modules on the roof, the ground or as
a panel on top of a pole.
Rated output of a module - The DC power output of a module under
standard test conditions, (the module is at 25 degrees C and 1000
W/sq.m. of solar irradiance, and typically ranges from 100 to 340
watts). It is important to note that the actual operating
conditions will usually be different from the standard test
conditions. 1000 W/sq.m. can be thought of as the solar intensity
of a clear sunny day. If the temperature of the panel is more than
25 degrees C (77F) it will reduce the output that you get from the
panels, or if the panel is colder, the DC output can actually be
higher than "rated".
Tilt (or tilt angle) - The angle of inclination of a solar panel
or solar module measured from the horizontal (plane of the
Watt - see kilowatt.
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