Glossary
Alternating Current or AC
AC is the form of electricity that
is delivered to your home or
business by an electric utility.
Solar PV systems produce DC,
which must be converted to AC
by an inverter.
Array
Any number of electrically
connected PV panels providing
a single electrical output.
Capacity Rating
The rating given to a PV system
by its manufacturer denoting
the load the system is able to
meet or supply when operating
at full capacity in direct sunlight
with no shade.
CEC-AC Rating
The calculation that provides a
total estimated energy output
of a solar generation system,
factoring in the efficiency of the
panels and inverter.
Conversion Efficiency
The amount of the sun’s energy
that a solar cell can convert into
electricity; the balance is lost as
heat or reflected light.
Direct Current or DC
Solar PV systems produce
electricity in DC, which is
defined as the continuous flow
of electricity through a
conductor. DC power is
converted to AC by an inverter
to power homes and
businesses.
Greenhouse Gas or GHG
The gases responsible for
trapping heat from the sun
within Earth’s atmosphere (i.e.,
water vapor, carbon dioxide,
methane, ozone,
chlorofluorocarbons and
nitrogen oxides). GHGs are
released from many sources,
including industrial processes
such as power generation from
fossil fuels.
Grid
A network of power stations,
transmission circuits and
substations that conduct
electricity and provide it to
homes and businesses
Grid-Connected or Grid-Tied PV
System
A PV system in which the PV
array is wired into buildings or
residences that are connected
to the utility grid. This allows
customers to feed excess
electricity into and pull needed
electricity from the grid.
Interconnection Agreement
A legal document between the
customer and their electric
utility authorizing the
connection of the customer’s
solar generation system to the
utility’s grid. This agreement is
required prior to the utility
granting permission to operate.
Inverter
A device that converts DC
electricity produced by a solar
generation system into AC
electricity that can be used in a
home or business. Some energy
is lost when this conversion
takes place (see CEC-AC rating).
Inverter Efficiency
The AC power output of the
inverter divided by the DC
power input. Inverter efficiency
is lowest when operating at low
loads; thus, it is important to
select inverters of the proper
size relative to the PV array.
Kilowatt or kW
A unit of electrical power equal
to 1,000 W, which constitutes
the basic unit of electrical
demand. The watt is a metric
measurement of power (not
energy) and is the rate (not the
duration) at which electricity is
used. 1,000 kW is equal to one
megawatt (MW).