SOLAR
TERMINOLOGY – GLOSSARY AND DEFINITIONS
AC - Alternating Current the standard form
of electrical current supplied by the utility grid and by most
fuel-powered generators. The polarity (and therefore the
direction of current) alternates. In U.S.A., standard voltages
for small water pumps are 115V and 230V. Standards vary in
different countries. See inverter.
Amorphous - There are two main types of
solar panel: amorphous and crystalline. In general, amorphous
perform better than crystalline under low light conditions and
don’t suffer as much power loss in hot temperatures. However,
in good conditions, the efficiency of amorphous panels is lower,
and they are physically larger than crystalline panels of the
same wattage.
Amp Hour (Ah) - Measures a battery's total
capacity. The higher the number, the larger the battery's
capacity.
Amps - Measures the strength of an
electrical current.
Blocking Diode - At night a blocking diode
prevents the solar panel from acting as a power drain on your
battery. Charge controllers (or regulators) include a feature
that does the same job as a blocking diode.
Bypass Diodes - These are placed within
some solar panels at the manufacturing stage. If the solar panel
is partly in shadow, bypass diodes prevent the shadowed cells
from acting as a power drain on those cells still in the
sunlight.
Converter - An electronic device for DC
power that steps up voltage and steps down current proportionally
(or vice-versa). Electrical analogy applied to AC: See
transformer. Mechanical analogy: gears or belt drive.
Crystalline - Crystalline silicon is
generally either Mono-crystalline or Poly-crystalline. These
solar panels tend to be rigid, aluminium framed and glass
fronted. In good conditions they can be more efficient and
physically smaller than amorphous panels of the same wattage.
Current - measured in Amps (I), is the
system power divided by system voltage. I = W / V.
Current - The rate at which electricity
flows through a circuit, to transfer energy. Measured in Amperes,
commonly called Amps. Analogy: Flow Rate in a water pipe.
DC - Direct Current, the
type of power produced by photovoltaic panels and by storage
batteries. The current flows in one direction and polarity is
fixed, defined as positive (+) and negative (-). Nominal system
voltage may be anywhere from 12 to 180V. See voltage, nominal.
Efficiency - The
percentage of power that gets converted to useful work. Example:
An electric pump that is 60% efficient converts 60% of the input
energy into work - pumping water. The remaining 40% becomes waste
heat.
Efficiency - The ratio of sunlight power
hitting the solar cell to the electrical power it produces.
Mono-Crystalline efficiency is in the region of 14% to 18%.
Energy - The product of power and time,
measured in Watt-Hours. 1000 Watt-Hours = 1 Kilowatt-Hour
(abbreviation: KWH). Variation: the product of current and time
is Ampere-Hours, also called Amp-Hours (abbreviation: AH). 1000
watt consumed for 1 hour = 1 KWH. See power.
Environmentally friendly - Inflicting
minimum harm on the environment.
Flexible panel - The solar amorphous panel
is usually mounted onto a thin metal or plastic backing and
sealed at the edges using a pliable material, thus allowing the
panel to be slightly bent.
Framed panel - Solar panel mounted onto a
thin metal backing plate which is then mounted into an aluminium
frame that can be used to attach the solar panel to a building,
roof or other structure.
Green energy - Energy produced in way that
is sympathetic to the environment, producing less pollutants such
as carbon emissions.
Insolation - The amount (and type) of light
defined below, falling on the surface of a solar cell.
Inverter - An electronic device that converts low voltage DC to
high voltage AC power. In solar-electric systems, an inverter may
take the 12, 24, or 48 volts DC and convert it to 115 or 230
volts AC, conventional household power.
Ip - The current of the panel at peak power
output.
Isc - Short circuit Current = maximum
current that the panel can generate (very little voltage).
Milli Amp hour (mAh) - Measures a battery's
total capacity. The higher the number, the larger the battery's
capacity.
NOCT - Normal Operating Cell Temperature =
the temperature at which a cell operates with full sunlight
falling on its surface (and therefore heating it).
Open-circuit voltage - The open circuit
voltage is the maximum voltage that the panel can produce. The
panel is not producing its maximum power output when giving this
voltage.
Photovoltaic - Photovoltaic (PV) technology
converts sunlight into electricity. Often referred to as PV for
short, photo means 'light' and 'voltaic' means electric.
Photovoltaic - The name given to the
process of converting radiation (especially light) directly into
electricity. As in this document, the term 'solar' is commonly
used to refer to what should strictly be called photovoltaic.
Photovoltaic - The phenomenon of converting
light to electric power. Photo = light, Volt = electricity.
Abbreviation: PV. PV - The common abbreviation for photovoltaic.
Power - measured in Watts (W), is the
system voltage multiplied by system current. W = V x I.
Power - The rate at which work is done. It
is the product of Voltage times Current, measured in Watts. 1000
Watts = 1 Kilowatt. An electric motor requires approximately 1
Kilowatt per Horsepower (after typical efficiency losses). 1
Kilowatt for 1 Hour = 1 Kilowatt-Hour (KWH).
PV Array - A group of PV (photovoltaic)
modules (also called panels) arranged to produce the voltage and
power desired.
PV Array-Direct - The use
of electric power directly from a photovoltaic array, without
storage batteries to store or stabilize it. Most solar water
pumps work this way, utilizing a tank to store water.
PV Cell - The individual photovoltaic
device. The most common PV modules are made with 33 to 36 silicon
cells each producing 1/2 volt.
PV Module - An assembly of PV cells framed
into a weatherproof unit. Commonly called a "PV panel".
See PV array.
Rated Power - The amount of electrical
power produced by a solar panel when exposed to sunlight at an
intensity of 1000W per meter squared. The rated power is measured
in Watts.
Renewable energy - Energy obtained from
inexhaustible sources, such as solar energy and wind power.
Rollable panel - The solar amorphous panel
is mounted onto a plastic backing, and can be usually rolled to a
diameter of around 8 inches or 20cm. The panel needs to be rolled
with the solar cells on the outside.
Short-circuit current - The short circuit current is the maximum
possible current that the panel can produce. The panel is not
producing its maximum power output when giving this current.
Solar - Utilising the sun's energy or
derived from the sun.
Solar array - A collection of two or more
solar modules.
Solar cell - A semi-conducting material
that converts light to DC electricity. It is the smallest
generating element of a PV system.
Solar cell - The smallest single solar
electric generating device.
Solar energy -Thermal energy or electricity
created from the sun's radiation.
Solar panel - A collection of solar cells
that convert the sun's energy into electricity.
Solar panel - A collection of two or more
cells; also referred to as a solar module. With TFS, the cells
are connected in series during the production process.
Solar power - Energy harnessed from the
sun's light.
Solar Tracker - A mounting rack for a PV
array that automatically tilts to follow the daily path of the
sun through the sky. A "tracking array" will produce
more energy through the course of the day, than a "fixed
array" (non-tracking) particularly during the long days of
summer.
Transformer - An electrical device that
steps up voltage and steps down current proportionally (or
vice-versa). Transformers work with AC only. For DC, see
converter. Mechanical analogy: gears or belt drive.
Triple junction - Triple junction is the
term used to describe the amorphous panel technology that is
sensitive to three wavelengths of light. This gives the these
panels a wider operating range.
Utility Grid - Commercial electric power
distribution system. Synonym: mains.
Vnom - Nominal voltage = the voltage at
which the solar cell or panel is designed to operate at.
Voc - Open circuit voltage = maximum
voltage that the panel can generate (very little current).
Voltage - measured in Volts (V), is the
system power divided by system current. V = W / I.
Voltage - The measurement of electrical
potential. Analogy: Pressure in a water pipe.
Voltage Drop - Loss of voltage (electrical
pressure) caused by the resistance in wire and electrical
devices. Proper wire sizing will minimize voltage drop,
particularly over long distances. Voltage drop is determined by 4
factors: wire size, current (amps), voltage, and length of wire.
It is determined by a consulting wire sizing chart or formula
available in various reference tests. It is expressed as a
percentage. Water analogy: Friction Loss in pipe.
Voltage, Nominal - A way of naming a range
of voltage to a standard. Example: A "12 Volt Nominal"
system may operate in the range of 11 to 15 Volts. We call it
"12 Volts" for simplicity.
Voltage, Open Circuit - The voltage of a PV
module or array with no load (when it is disconnected). A
"12 Volt Nominal" PV module will produce about 20 Volts
open circuit. Abbreviation: Voc.
Voltage, Peak Power Point - The voltage at
which a photovoltaic module or array transfers the greatest
amount of power (watts). A "12 Volt Nominal" PV module
will typically have a peak power voltage of around 17 volts. A PV
array-direct solar pump should reach this voltage in full sun
conditions. In a higher voltage array, it will be a multiple of
this voltage. Abbreviation: Vpp.
Volts - Measures the “pressure” in an
electrical circuit between two points.
Vp - The voltage of the panel at peak
(maximum) power output.
Watts - Measures total electrical power.
Watts=Volts x Amps.
Wp - The peak power that a solar cell/panel can produce.
