How does a Solar PV (Photovoltaic) System work?
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First, Solar panels installed on the roof or elsewhere convert sunlight into electricity. How?
Typically, you'll need a south-facing roof that is not shaded by trees
or other obstructions. We have device (called a Solar Pathfinder) that
can tell if shade is present on your roof at any time of the year.
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| This power from the solar panels, generated as Direct Current, is sent to a device called an inverter.
An inverter has several jobs.
1 - It converts the Direct Current form the solar panels into
Alternating Current, which is what your household appliances use.
(Some systems, such as 'off-grid' systems in houses that are too remote
for the utility to reach do not need an inverter because all of their
devices run on direct current). RV's and boats often have direct
current devices, too.
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2
- It matches the alternating current to the alternating current (AC)
that is coming from the utility grid. Inverters must meet exacting
standards in order to be approved for use. The California Energy
Commission manages a list of approved inverters here: California Energy Commission
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3
-The Inverter sends the electricity to the main circuit breaker panel
in the house. From there, the electricity can go into the house to run
appliances or, if there is more electricity being generated than is is
being used, it will go back into the utility grid. If permitted by
local Net-Metering laws, this will spin your electrical meter
backwards... effectively selling power back to the utility company. |
4 - The inverter 'watches' the utility grid so that it can shut down,
immediately, if the utility grid shuts down. This way, if a storm or
accident breaks an overhead electrical wire then your solar system will
not send power into the electrical system and endanger people.
Photovoltaic PV solar systems will only keep your lights on during a
power failure if you have batteries attached to the system.
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