PV (Photovoltaic) in your home
Solar photovoltaic cells are small, square shaped panel semiconductors
manufactured in thin film layers from silicon and other conductive materials.
When sunlight strikes the PV cell, chemical reactions release electrons,
generating electric current. The small current from individual PV cells, which
are installed in modules, power individual homes and businesses, or can be
plugged into the bulk electricity grid.
Solar PV has come a long way since its early origins in the space program
powering satellites and other extraterrestrial vehicles more than four decades
ago. The technology has come down to earth and now is the first power supply
choice for much of the developing world. They are also appearing on rooftops and
years around our state to provide power during daylight hours.
There are two primary PV markets. Off-grid systems are used where the cost of
a PV system is cheaper than stringing electrical power lines long distances from
the local utility. Grid-connected PV systems usually cannot compete directly
with the cost of utility-produced power. However, with the changing deregulated
marketplace, many people are considering grid-connected PV systems. If the PV
system provides more power than the home or business uses, additional
electricity is fed back into the grid for other people to use. This effectively
spins an electricity meter backward in what is known as "net
metering."
Incentives are being offered to homeowners and small businesses by some
states to help develop a more robust PV industry. In California, incentives from
the Emerging
Renewable Buy-Down Program can reduce the cost of a grid-connected system by
up to 50 percent. Nationally, the Million Solar Roofs program begun by President
Bill Clinton in 1997 has supported the installation of 70,000 PV systems by the
end of 1999.
Photovoltaics or solar cells can be purchased in two formats: as a
stand-alone module that is attached to your roof or on a separate system, or
using integrated roofing materials with dual functions -- that as a regular
roofing shingle and as a solar cell making electricity.
Because they do not produce polluting air emissions or water effluents, solar
PV systems are prime candidates for supplying electricity at locations where
such environmental impacts are unacceptable; for example, in parks and places
where preserving high levels of environmental quality is important.
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There are several solar PV products on the market.
One of the more intriguing recent advances was just announced by Toshiba for
the Graetzel cell, a new type of solar panel that consists primarily of
titanium dioxide nanocrystals coated with a dye. The new cells could be
manufactured by silk-screen printing technologies. At present, at least seven
companies in Japan, Europe and Australia are developing improved Graetzel cells
that may end up gracing cell phones, laptops and even windows in
energy-efficient homes.
BP Solar panels which quietly and beautifully transform atria, glass
roofs and roof lights into electricity generators. The most impressive products,
nevertheless, are PowerWalls, which arrange solar cells in patterns framed by
curtain walls erected with traditional glazing techniques.
Powerlight Corporation of Berkeley, California, has developed a unique
mounting platform that integrates a variety of PV products into rooftops. A foam
insulation reduces heating and air-conditioning costs. The light-weight solar PV
modules also extend the life of the roof by protecting it from the damaging
effects of weather.
The building-integrated products manufactured by Atlantis Energy of
Grass Valley, California, offers custom glass PV laminates, which turn windows
into micro-power plants.
For a list of California Energy Commission-certified PV Systems and
Inverters, see our Buy-Down
Program page.
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The cost of a PV system depends on the system's size, equipment options and
labor costs. Prices vary depending on other factors as well, such as the PV
provider, whether or not your home is new, if the PV is integrated into the
roofing materials or mounted on top of the existing roof, and the PV
manufacturer. Small systems funded through California's Buy-Down Program have
been averaging $7.00 / watt, after rebates.
To fund a PV-System in California, please visit our Renewable
Energy Buy-Down Program page.
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The property should have clear, unobstructed access to the sun for most of
the day and free from shade. The best orientation for a PV system is on a
south-facing roof. If your location looks promising, a PV provider can trace the
sun's path for you and determine whether your home or business would benefit
from a PV system. Typically, composition shingle roofs are the easiest to work
with.
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State laws in California protect homeowner's access to the sun for solar
systems. A portion of the Warren_Alquist
Act -- Public Resources Code Section 25980-25986, the Solar Shade Control
Act, states "...It is the policy of the state to promote all feasible means
of energy conservation and all feasible uses of alternative energy supply
sources. In particular, the state encourages the planting and maintenance of
trees and shrubs to create shading, moderate outdoor temperatures, and provide
various economic and aesthetic benefits. However, there are certain situations
in which the need for widespread use of alternative energy devices, such as
solar collectors, requires specific and limited controls on trees and
shrubs."
If you have questions regarding this law, please check with your legal
adviser, county building official or your solar equipment installer.
More Informattion About PV Systems for Homes and Business
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