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| Solar
Power System |
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A
system used to transform solar radiation
directly into electricity. At the heart
of a solar power system, also
known as a photovoltaic (PV) system or solar
electric system, are solar cells,
which are interconnected to form solar
modules (solar panels) and solar
arrays.
The size
and configuration of a system depend on its intended task.
Modules and arrays can be used to charge batteries, operate
motors, and to power any number of electrical loads. With
the appropriate power conversion equipment, solar power systems
can produce alternating current (AC) compatible with any conventional
appliances, and can operate in parallel with, and interconnected
to, the utility grid (see grid coupling).
Among
the components of a complete solar power system may be a DC-AC
power inverter, a battery bank, a system and battery controller,
auxiliary energy sources, and sometimes the specified electrical
load (appliances). In addition, an assortment of balance of
system (BOS) hardware, including wiring, overcurrent, surge
protection and disconnect devices, and other power processing
equipment. |
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The
two main types of solar power systems are stand-alone systems
and grid-connected or utility-interactive systems.
Stand-alone
Solar Power Systems
These
are designed to operate independent of the electric utility
grid, and are generally designed and sized to supply certain
DC and/or AC electrical loads. They may be powered by a solar
array only, or may use wind, an engine-generator, or utility
power as an auxiliary power source in what is called a solar-hybrid
system.
The simplest
type of stand-alone system is a direct-coupled system, where
the DC output of a solar module or array is directly connected
to a DC load. |
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| Since
there is no electrical energy storage (batteries) in direct-coupled
systems, the load only operates during sunlight hours, making
these designs suitable for common applications such as ventilation
fans, water pumps, and small circulation pumps for solar thermal
water heating systems. Matching the impedance of the electrical
load to the maximum power output of the PV array is a critical
part of designing well-performing direct-coupled system. For
certain loads such as positive-displacement water pumps, a type
of electronic DC-DC converter, called a maximum power point
tracker (MPPT), is used between the array and load to help better
utilize the available array maximum power output.
In many stand-alone
solar power systems, batteries are used for energy storage.
The following diagram is of a typical stand-alone system powering
DC and AC loads.
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| This
is how a typical solar hybrid system might be configured. |
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Grid-connected
Solar Power Systems
These
are designed to operate in parallel with, and interconnected,
with the electric utility grid. The primary component in grid-connected
systems is the inverter, or power conditioning unit (PCU).
The PCU converts the DC power produced by the solar array
into AC power consistent with the voltage and power quality
requirements of the utility grid, and automatically stops
supplying power to the grid when the utility grid is not energized.
A bi-directional interface is made between the solar power
system AC output circuits and the electric utility network,
typically at an on-site distribution panel or service entrance.
This allows the AC power produced by the solar power system
to either supply on-site electrical loads, or to back-feed
the grid when the solar power system output is greater than
the on-site load demand. At night and during other periods
when the electrical loads are greater than the solar power
system output, the balance of power required by the loads
is received from the electric utility. This safety feature
is required in all grid-connected systems, and ensures that
the system will not continue to operate and feed back into
the utility grid when the grid is down for service or repair.
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| Solar
power systems are able to operate normally in grid-connected
mode and still operate critical loads when utility service is
disrupted, providing that battery storage is used. This type
of system is popular for homeowners and small businesses where
a critical backup power supply is required for critical loads
such as refrigeration, water pumps, lighting, and other necessities.
Under normal circumstances, the system operates in grid-connected
mode, serving the on-site loads or sending excess power back
onto the grid while keeping the battery fully charged. In the
event the grid becomes de-energized, control circuitry in the
inverter opens the connection with the utility through a bus
transfer mechanism, and operates the inverter from the battery
to supply power to the dedicated loads only. In this configuration,
the critical loads must be supplied from a dedicated sub panel.
The diagram below shows how a solar power system might be configured
to operate normally in grid-connected mode and also power critical
loads from a battery bank when the grid is de-energized. |
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Solar
Panel Diagram
The solar
panel diagram below shows how solar energy is converted
into electricity through the use of a silicon cell. The below
image is not a solar panel wiring diagram, if you need access
to a wiring plan, you should consult a specialist electrician,
or solar installer.
In the
diagram below you can see how a solar panel converts sunlight
into energy to provide electricity for a range of appliances.
This energy can be used for heating, through the use of solar
hot water panels, or electricity through the use of regular
cells. |
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The
Theory Behind The Solar Panel Diagram
As you
can see from the above diagram of a solar panel, photons are
contained within the suns rays and beam down to earth. Once
these photons reach the solar panel, they are absorbed by
the silicon material, and this allows electrons to be knocked
off their orbit.
As the
electrons are knocked off their orbit, they become free electrons
and are able to pick up a current, resulting in the flow of
electricity to external sources.
Some modern
designs of solar panels use a vacuum in their design to allow
for more efficient electricity production on overcast days.
This shows how new technologies are making renewable energy
devices much more efficient and a viable contender for electricity
from fossil fuels.
The
Use Of Electricity From Solar Panels
As the
solar panel diagram shows, you can see how power is sourced
out to various locations, this depends on how you plan to
use the energy harnessed from a solar cell.
Possible
uses of solar electricity could be to provide direct current
into an existing power supply, provide a separate power supply
dependent upon the solar panel, or to charge solar batteries
for the storage of solar electricity.
Solar
panels are even used to heat water in some modern designs.
Some home swimming pools also use solar energy to heat the
water.
Solar
energy has a huge advantage for providing electricity in remote
locations due to the fairly simple method of installation.
A remote solar panel system can provide electricity for vital
tasks where the laying of electricity cable is not practical,
a working example of this is on satellites. |
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