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The science of photovoltaics
Photovoltaics are solid-state semiconductor devices that convert light directly into electricity. They are usually
made of silicon with traces of other elements and are first cousins to transistors, LEDs, computer chips and other electronic
devices.
A photovoltaic device (generally called a solar cell) consists of layers
of semiconductor materials with different electronic properties. In a typical Solar crystalline silicon cell, the bulk of
the material is silicon, doped with a small quantity of boron to give it a positive or p-type character. A thin layer on the
front of the cell is doped with phosphorous to give it a negative or n-type character. The interface between these two layers
contains an electric field and is called a junction. Light consists of particles called photons. When light hits the solar
cell, some of the photons are absorbed in the region of the junction, freeing electrons in the silicon crystal. If the photons
have enough energy, the electrons will be able to overcome the electric field at the junction and are free to move through
the silicon and into an external circuit. As they flow through the external circuit they give up their energy as useful work
(turning motors, lighting lamps, etc.) and return to the solar cell. The photovoltaic process is completely solid-state and
self-contained. There are no moving parts and no materials are consumed or emitted.
PV and the Environment
Photovoltaics
are probably the most benign method of power generation known. They are silent, produce no emissions, and use no fuel (other
than sunlight!). The production of photovoltaics, of course, varies among manufacturers. Most module manufacturers make extensive
use of recycled materials and even use waste from other industries as raw material. PV technology is based on silicon,
the second most common element on the earth's surface. As used in PV modules, silicon is non-toxic. A Solar PV module
will re-generate the energy used in its manufacturing process in 1 to 4 years depending on the application and location.
PV performance factors
Weather naturally
affects the performance of PV, but not entirely as you might expect. The amount of sunlight, of course, is most important
in determining the output a solar electric system will produce at a given location, but temperature is also important. Contrary
to most people's intuition, photovoltaics actually generate more power at lower temperatures with other factors being
equal. This is because photovoltaics are electronic devices and generate electricity from light, not heat. Like most electronic
devices, photovoltaics operate more efficiently at cooler temperatures. In temperate climates, photovoltaics will generate
less energy in the winter than in the summer, but this is due to the shorter days, lower sun angles and greater cloud cover,
not the cooler temperatures.
Residential Solar Systems allow you to generate clean, renewable electricity
right at home, reducing your utility bills for years to come. Although the technology is complex, systems are simple to install
and maintain.
A practical energy solution
When sunlight shines onto a solar panels, technology transforms the light into DC electricity. That DC electricity
is then converted to AC electricity (via an inverter) that is used throughout your home. During the day, if your solar home
solution produces more electricity than is used in your home, the extra electricity produced is fed into the utility grid
generating a credit on your electric bill. When this happens, you'll be able to see your utility meter actually spin backwards.
At night, electricity is automatically drawn from the grid to provide your home with the power you need. Battery option
With batteries added to your solar home solution, extra electricity
produced by your system is captured in the high capacity batteries for later use. This option is a perfect solution for homes
that do not have easy access to a utility grid or are located in areas that experience frequent outages.
When your local electrical grid shuts down for any reason, including
rolling blackouts or storm damage, any home solar system without batteries must shut down as well. This safety precaution
prevents random surges of power from traveling the grid and causing injury or damage. However, if battery backup is included
in your system you won't experience this inconvenience. When a power outage occurs in your area, your solar system will
disconnect itself from the grid and draw power from the batteries. When grid power returns to normal, the system automatically
reconnects.
A commercial solar electric system is a reliable way to promote efficiency and reduce costs without
affecting on-going operations
A solar electric system
provides reliable electricity that augments the energy a facility receives from traditional sources such as the local utility.
Typically supplying 10% to 40% of a conventional facility's electrical load, it integrates seamlessly with existing electrical
and mechanical systems.
 Diagram of a commercial solar system Practical electricity from the sun
The building block of any solar electric system is the solar cell. Using technology related to semiconductors, solar
cells convert sunlight into usable electricity without moving parts, noise, or pollution. In order to enable practical installation
in the field, these solar cells are connected and encased in a protective envelope in a factory to form a solar module. In
the field, the solar modules are then connected and attached to a support structure on a facility's roof, ground, or parking
areas to form solar arrays. Several arrays comprise a solar electric system or plant as shown in the diagram above.
Once installed and exposed to the sun, the solar electric system will produce direct current (DC) electricity - the same
type of electricity you get from a battery. Since most facilities use alternating current (AC) electricity, an inverter is
used to convert the DC power into AC power. The AC power then flows from the inverter to the facility to power electrical
loads such as lights, refrigerators, or computers, reducing the amount of power that is needed from the utility. If during
daylight hours, the facility is using less electricity than the solar array is providing, net metering (available in most
states) allows this excess power to flow through the utility meter to the utility grid, turning the utility meter backwards.
Worry-free
operation
A solar electric system integrates seamlessly with a facility's
existing systems. Because the facility is still connected to the utility grid, any demand in excess of what the solar electric
system provides is supplied from the utility. Whether it is sunny or cloudy, day or night, all electrical devices operate
normally and continue to receive power as required. High quality and Corona-Solar installed solar electric systems
comply with all necessary electrical and building codes.
Operating a solar electric system is simple and worry-free. Commercial systems are designed to be
low maintenance and include our solar management monitoring and management service. You get a solution that is
easy to operate and maintain.
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