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There are two main types of solar power, solar thermal and photovoltaic.
Solar thermal uses the sun light's infrared energy to either heat a
liquid or to warm a mass of material that will later on release its
stored heat. Harnessing solar thermal energy involves building a house
in such a way to collect the sun's heat during the day and radiate it
into the home during the evening. However, in the summer time the
house's construction uses mass to keep the sun's heat out of the home.
Solar photovoltaic energy converting sun light into electrical energy.
The most commonly associated component are the photovoltaic panels or
solar panels that you see mounted on roofs.
This article will be focusing on how photovoltaic solar power (solar
panels) and systems work.
Why are solar photovoltaic panels always on the south (or north) side of
the roof?
In order to get the maximum electrical output from photovoltaic panels
they need to be oriented to solar south in the northern hemisphere and
solar north in the southern hemisphere. Solar north and solar south are
the same as magnetic or compass north or south. There is about a fifteen
degree difference between them.
Most solar photovoltaic panels are set at home latitude plus fifteen
degrees or home latitude minus fifteen degrees. Depending on if you want
a summer or winter bias to the angle of the solar panels. In higher
latitudinal areas it makes more sense to have the photovoltaic panels
set on a winter bias, so that during the winter the solar panels still
get enough sun light to produce electricity.
How does a photovoltaic cell produce electricity?
A solar panel consists of a collection of photovoltaic cells. Each
photovoltaic cell is made up of silicon wafer. Silicon in its pure state
is a poor electrical conductor. During the manufacturing process, an
impurity is added to the silicon so that when the photons (light)
strikes the wafer electrons are released and create electrical current.
The type of electrical current produced by a solar panel is a low
voltage direct current, or DC, typically in the range of six to twenty
four volts. Photovoltaic panels have a nominal output voltage of 12
volts and an effective operating voltage of 17 or more volts.
A solar panel's electrical output is affected by several factors. They
are angle of the photovoltaic panels to the sun, time of day, time of
the year and weather conditions. Solar photovoltaic panels produce more
electricity during the middle of the day when the sun is directly
overhead compared to the early morning and late evening when the sun
light is striking the solar panel at a shallow angle.
Components of a residential solar power system
A residential solar power system consists of four components are:
photovoltaic panels, charging controller, battery pack and an inverter.
The photovoltaic panels convert sun light into electricity. The
electricity is sent to the charging controller who keeps the battery
pack fully charged, but not over charged. The battery pack sends the
electricity to the inverter who converts the DC voltage to household AC
at 120 volts and 60 hertz.
Photovoltaic panel
The output of a solar panel is stated in watts. The wattage is stated is
typically for peak sun hours. Since the amount of sun light varies
through the course of a day, to level out the variations the peak sun
hours has been adopted by most manufactures to help installers and
customer's compare different solar panel models.
Suppose a solar panel is rated for 100 watts and an average of six peak
sun hours is available per day. Then the solar panel would produce 100
watts * 6 peak hours = 600 watt hours of electricity or 0.6 kilo watt
hours (KWh).
Charging controller
Charging controller or charge regulator controls the charging of the
battery pack. It continually monitors the battery pack's charge state.
If the batteries are low, it will send electricity from the solar panels
to the batteries. It also prevents over charging of the battery pack.
Don't allow someone to convince you that a charging controller is not
really required. Directly connecting the photovoltaic panels to the
battery pack can permanently damage the batteries and possibly cause
them to explode.
Battery pack
The battery pack's purpose is to store electricity generated by the
solar panels during the day and then at night or during extremely cloudy
days provide electricity to the inverter.
The battery pack typically consists of lead acid batteries. Lead acid
batteries are relatively inexpensive and readily available. There are
many different types, sizes and capacities of batteries available. The
most popular are gel cell and AGM deep cycle batteries because they are
maintenance free and last a lot longer than wet cell lead acid
batteries.
The most important thing to remember about the batteries is that the
need to be deep cycle. Deep cycle batteries are designed to be
discharged then recharged hundreds if not thousands of times. A deep
cycle battery is designed to discharged to nearly empty, but not
completely and then be slowly recharged over time. A common mistake for
home owners is to think that they can use automotive batteries instead
of deep cycle batteries. Car batteries are shallow cycle batteries. They
are designed to discharge a lot of current quickly and then be
immediately recharged.
Inverter
An inverter converts the DC electricity stored in the battery pack into
household 120V AC. Almost everything in your home is powered by 120V
electricity. Things like table lamps, freezer, lights, motors,
dishwasher, and so on.
There are two main types of inverters sine wave and modified sine wave.
The power company provides electricity as a sine wave. The electricity's
charge value goes smoothly from positive 120V to 0V to negative 120V
and then back up to 0V and finally up to positive 120V. Then the cycle
begins all over again. The time it takes to go through the entire cycle
is one second.
Modified sine wave is also known as a square wave. Here the
electricity's charge value goes from positive 120V to negative -120
volts in effectively zero seconds.
Most household devices will function on a modified sine wave power.
Light bulbs and motors will work, just not quite as efficiently as they
would on sine wave electricity. However, there are some electronic
devices that will not work on square wave electricity. It will be
necessary to check with the manufacture to determine if the device will
work on square wave electricity.
Now you have a basic understanding of solar power how it works to power
your home. Now you have enough information about how solar power works
to determine if it is a technology that you would want to invest in for
your house.
Article Source: http://www.solarenergyarticles.com
Want more information on solar power installer? Try visiting
www.homesolarpowerguide.com, a popular website that offers tips, advice
and resources related to solar power. By Willhelm at homesolarpowerguide
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