How do solar panels work? If you are thinking of installing
solar panels for your home or building, you should at least have a general
understanding of how solar panels work.
A solar panel simply put is a collection of solar cells. They work
together to supply electricity for various uses. A single cell does not have
the capacity for generating a lot of electricity so multiple cells are
connected together to increase the capacity, how many cells depends on the
amount of electricity required. The more light available to the solar panels
the greater the amount of electricity they can supply.
Solar panels are designed to convert light into electricity. The process
of extracting electricity from light is called Photovoltaic (PV) and the PV
process converts solar energy directly into electricity. PV cells are formed
from a wafer of semi-conductor material. Although there are now
several types in production using different materials, the most common
semi-conductor used is silicon.
Pure crystalline silicon is a poor electrical conductor, but treat it
with tiny quantities of an impurity, either phosphorous or arsenic
(a
process called "doping"), and enough electrons of these materials are freed
to enable a current to pass through. Electrons are negatively charged so
this type of silicon is called N-Type.
Dope silicon with gallium or boron and "holes"are created in the
crystalline lattice where a silicon electron has nothing to bond with. These
holes can conduct electrical current and the lack of an electron creates a
positive charge so this type of silicon is therefore called P-Type. Both
types of silicon are modest electrical conductors, hence the name
semiconductors.
Put a layer of each kind together in a wafer, such as in a PV cell, and
the free electrons in the N side migrate towards the free holes on the P
side. This causes a disruption to the electrical neutrality where the holes
and electrons mix at the junction of the two layers. Eventually a barrier is
formed preventing the electrons from crossing to the P side and an
electrical field is formed, separating both sides. This electrical field
acts as a diode, allowing electrons to pass from the P side to the N side,
but not vice versa.
Expose the cell to light, and the energy from each photon (light
particle) hitting the silicon, will liberate an electron and a corresponding
hole. If this happens within range of the electric field's influence, the
electrons will be sent to the N side and the holes to the P one, resulting
in yet further disruption of electrical neutrality. Apply an external
pathway connecting both sides of the silicon wafer and electrons will flow
back to their original P side to unite with the holes sent there by the
electric field.
This flow of electrons is a current; the electrical field in the cell
causes a voltage and the product of these two is power.
Several factors affect the efficiency of a solar cell. One
fact is solar insolation, a measure of how much solar radiation a given
solar panel or surface receives. The greater the insolation, the more solar
energy can be converted to electricity by the solar panel. Other facts
that affect the output of solar panels are weather conditions, shade caused
by obstructions to direct sunlight, and the angle and position at which the
solar panel is installed. Solar panels function the best when placed in
direct sunlight, away from obstructions that might cast shade, and in areas
with high regional solar insolation ratings.
Solar panel efficiency can be optimized by using dynamic mounts that
follow the position of the sun in the sky and rotate the solar panel to get
the maximum amount of direct exposure during the day as possible. For more
information on solar panel efficiency through the use of mounts, see our
section on solar panel mounts and accessories.
Milholland Electric is a licensed electrical contractor in
California and Arizona with an experienced team in solar panel design and
solar panel installation and maintenance. Contact us for a
free estimate today!
