Velleman SOL14 Manuale Utente
Information sheet
©Velleman
Components nv
1/6
Last update: 16/04/2009
1) Solar Panels - Basics
A solar cell, sometimes called a photovoltaic cell, is a
device that converts light energy into electrical energy.
A single solar cell creates a very small amount of energy
so solar cells are usually grouped together in an
integrated electrical panel called a solar panel. Sunlight
is a somewhat diffuse form of energy and only a portion
of the light captured by a solar cell is converted into
electricity. The current generation of solar cells convert
only
device that converts light energy into electrical energy.
A single solar cell creates a very small amount of energy
so solar cells are usually grouped together in an
integrated electrical panel called a solar panel. Sunlight
is a somewhat diffuse form of energy and only a portion
of the light captured by a solar cell is converted into
electricity. The current generation of solar cells convert
only
12%
to
15%
of
the
sun's
light
into
electricity. However in recent years there have been
significant improvements in their design. Some new cells on the market now have
efficiencies around 20% while some laboratory prototypes even reach as much
as 30%. Given this it is likely that solar cell efficiency will continue to improve over
time.
significant improvements in their design. Some new cells on the market now have
efficiencies around 20% while some laboratory prototypes even reach as much
as 30%. Given this it is likely that solar cell efficiency will continue to improve over
time.
The output of a solar panel is usually stated in watts. The amount of watts of
electricity generated by a panel is determined by multiplying the rated voltage by the
rated amperage. The formula for wattage is:
electricity generated by a panel is determined by multiplying the rated voltage by the
rated amperage. The formula for wattage is:
VOLTS x AMPS = WATTS
Let's use as an example a large solar panel measuring about 1 x 1,5m that might be
used in a typical home energy system. The solar panel has a rated voltage of 26V
and rated amperage of 7A. The wattage calculation would look like this:
used in a typical home energy system. The solar panel has a rated voltage of 26V
and rated amperage of 7A. The wattage calculation would look like this:
26V x 7A = 182W
If a particular location has an average of 6 hours of peak sun per day, then the solar
panel in this example can produce an average of 1092Wh (6 x 182) power per day or
a little over 1kWh per day. Most homes use between 10-25kWh per day. Given this it
is going to take a lot more than one solar panel to generate enough electricity to
completely power a home. For a household needing 20kWh per day it would take
approximately 19 panels to provide 100% of the electricity. Most houses do not have
enough space on their south facing roof for this amount of panels.
panel in this example can produce an average of 1092Wh (6 x 182) power per day or
a little over 1kWh per day. Most homes use between 10-25kWh per day. Given this it
is going to take a lot more than one solar panel to generate enough electricity to
completely power a home. For a household needing 20kWh per day it would take
approximately 19 panels to provide 100% of the electricity. Most houses do not have
enough space on their south facing roof for this amount of panels.
Consequently, in most home applications where a connection to the grid is available,
a solar panel system should only provide part, but not all of the necessary energy.
a solar panel system should only provide part, but not all of the necessary energy.
2) Solar Panels – Functionality
A solar cell is based upon the "photovoltaic effect" (PV-effect) discovered in 1839 by
Edmund Becquerel, a French physicist. In his experiments he found that certain
materials would produce small amounts of electric current when exposed to
sunlight. Sunlight is made up of packets of energy called photons. When the photons
strike the semi-conductor layer (usually silicon) of a solar cell a portion of the photons
are absorbed by the material rather than bouncing off of it or going through the
material. When a photon is absorbed the energy of that photon is transferred to an
electron in an atom of the cell causing the electron to escape from its normal
position. This creates, in essence, a hole in the atom. This hole will attract another
electron from a nearby atom now creating yet another hole, which in turn is again
filled by an electron from another atom. This hole filling process is repeated a few
zillion times, thus creating an electric current.
Edmund Becquerel, a French physicist. In his experiments he found that certain
materials would produce small amounts of electric current when exposed to
sunlight. Sunlight is made up of packets of energy called photons. When the photons
strike the semi-conductor layer (usually silicon) of a solar cell a portion of the photons
are absorbed by the material rather than bouncing off of it or going through the
material. When a photon is absorbed the energy of that photon is transferred to an
electron in an atom of the cell causing the electron to escape from its normal
position. This creates, in essence, a hole in the atom. This hole will attract another
electron from a nearby atom now creating yet another hole, which in turn is again
filled by an electron from another atom. This hole filling process is repeated a few
zillion times, thus creating an electric current.