Batteryless Grid-Tie
Electric Power Systems
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Just what is a grid-tied PV system?
It is a photovoltaic (PV) system interacting
with the utility, and can be with or without batteries,
that utilizes relatively new breed of inverters that can actually
sell any excess power produced by your solar array back to the utility
grid. If you are concerned at all about your utility rates going up
and would like to do something to reduce your monthly electric bill,
then a grid-tie solar system may be just the thing for you. These
systems are easy to install and since some do not have batteries for
back-up, the lack of batteries in these systems means no messy
maintenance or replacements to worry about. The solar modules can
be mounted on your roof or out in the yard where they sit quietly
generating power from the sun that you can either use directly or sell
back to the utility company.
If that sounds pretty interesting, you might want to look into what
it would take to install a grid-tie PV system. The first thing you
should do is contact your utility company to see if they will allow you
to connect a solar system to their electrical grid. While there is
a national law that requires investor owned utility companies to allow
interconnection of a solar or wind power system, rural electric
cooperatives are exempt from this law. If your utility company
will allow you to connect your PV system to their grid, the next
question to ask is if they will buy the energy back at the retail or
wholesale rate. Ideally you want the utility company to buy back
any excess electricity that you produce at the same retail rate that you
buy electricity from them at. This is called "net
metering" and is the simplest way to setup a
grid-tie PV system. In such a system you only have one utility kWh
meter and it is allowed to spin in either direction depending on if you
are buying or selling energy. In a non net-metered system, the
utility company will require that you install a second kWh meter to
record any excess energy that you sell back to them and they will only
pay you the wholesale rate (usually only a few cents per kWh). To
find out if your state offers "net metering" or any other
incentives for installing a renewable energy system, click on the
following link (www.dsireusa.org).
Remember, a "net metering" law for your state
doesn’t necessarily apply to rural electric cooperatives so give your
utility company a call before going any further.
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links:
Which Grid-tie inverter is right for
me?
Sample residential
grid-tie system
Sample commercial grid-tie
system
More sample utility-tie power
systems
Insolation Zone map |
The next step is to figure out what size
system will work best for you. This is tricky because it all
depends on how much energy you want the system to produce per day, what
your utility rate is per kWh and of course how much money you want to
spend on a system. Your location is a big factor in determining
how much energy any grid-tie PV system will produce since everybody
knows that Las Vegas gets a lot more sunshine than Seattle. The
higher your utility rate is (¢/kWh), the more economical a grid-tie PV
system becomes since you are offsetting expensive energy that you would’ve
bought from the utility company with clean free energy from the sun. To
show you how much a grid-tie PV system can save you per year on your
electric bill, we have put together a couple of example systems to the
left. Call or email for
more specifics. |
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For other power inverters visit the
following links:
* Xantrex Trace
DR power inverters Extremely versatile modified sinewave inverter,
designed for prime power systems, utility back-up.
* Xantrex Trace
SW power inverters - Pure sinewave power, grid-interactive
capability, high surge capacity, low idle current and varied
programmability make this one of the most popular inverters. You
can also visit Xantrex web site at
www.xantrex.com for
further product information.
* Outback
Power sine wave power inverter systems - Stackable inverters of
modular design that have system expandability in mind. visit their
informative web site at
www.outbackpower.com.
* SMA America manufactures the Sunny Boy, their batteryless grid-tie
inverter, and you can view their product information at
www.SMA-AMERICA.com.
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