Solar electric System
As
today’s costs of energy rise, solar power is becoming more popular than
ever. There is an annual growth rate of over 30% within the
industry. It is true that a system, purchased and installed
commercially, can cost 10’s of thousands of dollars, by doing it
yourself and starting small, You can save a lot. Even installing
a small system into your home, you will see a smaller electric bill.
Your solar electric system can fall into
two classifications, on grid or off grid. An on grid system is
connected to the local power lines and will supply our home with
electricity only while the panels are producing electricity. The
off grid system is not connected to a electrical provider, and has it’s
own battery bank for storage of energy. This way energy is still
provided by your solar system, even when the sun is not out and
available. A hybrid system is one, which is still attached to the
local electrical supply, and also has the battery storage.
The variety of components of these systems
will be discussed below.
Solar
Panel
The main, and most obvious part of any
solar electric system is the solar panel. Each panel is comprised
of multiple photovoltaic (PV) cells. A PV cell is a small
instrument that takes sunlight and converts is into electricity using
the photovoltaic effect. PV cells are also called solar
cells. Each cell produces a relatively small amount of electrical
power; therefore, it must be connected to a large quantity of other
cells in order to secure worthwhile power levels. The PV cells
are mounted on a sturdy substrate and wired together to obtain the
amount of electricity needed. The whole thing is then mounted
within a frame and covered with a weather-tight layer of glass or
Plexiglas.
Several panels are then attached together
and mounted to form a solar panel array. The array is then placed
in the area on or around your home that receives the most amount of
sunlight and the least amount of shade. This can be on the roof,
the top of a pole, or even at ground level.
Solar Power Battery
The solar power battery is used to store
the extra power created by the panels, to be used at night or when the
sun is not accessible. Batteries are electrochemical devices and
their performance is determined by age, charge/discharge cycle history
climate and temperature. Though there are many types of battery
technologies, lead-acid batteries offer the best performance to dollar
ratio and are the most commonly used in solar power systems.
The capacity of a battery is listed as
amp-hours at a specific voltage. This means that a 100 amp-hour,
12-volt battery will provide 12 volts at 1 amp for 100 hours. The
battery bank should be sized for the ability to store enough power for
5 days without sunlight. It should also be a deep-cycle
battery. This means that the unit is capable of discharging most
of its power before being recharged. Vehicle batteries are
‘shallow-cycle’ and thus, are not good for solar power uses.
Solar Power Charge Controller
To lengthen the life of the battery pack,
a controller is normally prescribed. The controller monitors the
voltage of the battery and as the voltage increases it reduces, or
completely stops, the charging current thus preventing
over-charging. When the voltage drops again, the controller
allows the current to increase and continue to charge the battery.
Controllers are rated by the amount of
current they can manage. If there is any chance that you might
expand your system in the future, it’s a good idea to install a larger
capacity controller right from the start. Larger controllers are
not typically that much more cost wise.
Solar Power Inverter
The battery bank stores direct current
(DC) power from the solar panels. The low DC voltage has to be
converted into a higher AC voltage, such as 120 or 240 volts, to be
able to power appliances. This is the job of the inverter.
The inverter also creates the AC frequency, which is 60 Hertz
(cycles-per-second) for the USA. It also provides a sinusoidal
(sine) waveform, which most electronic appliances require.
The inverter must be able to accommodate
the required system power. Brand-name inverters are dependable
and maintain conversion proficiencies of approximately 90%.
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