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By Kim J. Gifford
Eet the sun shine in” could well be the cry of the
increasing number of consumers who are choosing
photovoltaic systems as a renewable energy source to
provide electricity for their homes.
History of Photovoltaics
Photovoltaic or solar cells are semiconductor
devices used to convert sunlight into direct current
(DC) electricity. Photovoltaic cells may be grouped
into modules and arrays capable of powering
everything from calculators to major electrical
appliances. An inverter, a type of power conversion
equipment, can help transform the DC output of a
photovoltaic system into alternating current (AC),
which is compatible with conventional appliances as
well as the utility grid.
According to the U.S. Department of Energy, the term
photovoltaics was first used in 1890. The term —
translated as “light-electricity” — is derived from
the Greek word for light, photo and volt, referring
to “electricity pioneer Alessandro Volta.” Yet,
photovoltaic cells did not come into production
until the late 1950s. They were subsequently used
throughout the 1960s to power satellites. The 1970s
introduced both manufacturing improvements and an
energy crisis, which helped spark an increased use
in photovoltaics and a move toward developing
systems capable of providing residential and
commercial power.
According to statistics from the Florida Solar
Energy Center, the production of photovoltaic
modules is growing at approximately 25 percent
annually. Here in the U.S. photovoltaic systems are
becoming increasingly popular. Vice President Jeff
Wolfe of Global Resource Options, a large northeast
distributor of photovoltaic systems located in
Strafford, Vt., says, “Our business is tripling
every year. The culture is beginning to understand
that not all electrons are created equal. For many
years, utility companies said cheap is good, and
that’s all you heard. People are realizing that
there is more they need to consider besides
expense.”
Brett Hamilton — project manager of The Renewable
Energy Resource Center, a project of the Vermont
Energy Investment Corporation — says he saw 200
renewable energy systems get underway in the state
of Vermont last year. “Easily a third of these were
photovoltaic systems by themselves and another large
group were hybrid systems using photovoltaics and
some other renewable energy source such as solar hot
water or wind. Over half the systems incorporated
photovoltaics,” he says.
The Pros of Photovoltaics
Photovoltaic systems provide a clean, renewable
source of energy. They require no moving parts, do
not create noise or pollution and rely on a readily
available source of fuel — sunlight. Photovoltaic
systems are typically the choice of consumers with a
concern for the environment or a desire to be
independent and take responsibility for the source
of their power.
Many people choose photovoltaic systems because they
live in remote areas removed from a utility company.
Darrell Thompson of Norwich, Vt., installed a
photovoltaic system because his house was off grid,
and “it would have been prohibitively expensive to
get connected to it,” he says. Yet, he has come “to
like the idea of the increased self-sufficiency that
the system allows and the apparently
environmentally-friendly generation of electricity.”
Laura Richardson of Benton Flats, N.H., decided on a
photovoltaic system for her home as it had always
been her husband’s dream. “He really liked the idea
of being off the grid,” she says. Although she was
“a little leery,” she joined her husband in
designing a 2,700-square-foot home, approximately
1,500 square-feet of which is regularly heated and
powered by photovoltaics. She became a convert and
is now president of the New Hampshire Sustainable
Energy Association.
In the past aesthetics may have been a drawback to
converting to solar energy. Today photovoltaics are
mounted in a variety of ways. Design considerations,
however, are different for on-grid and off-grid
systems. “It used to be that you put solar panels up
at weird angles that looked kind of ugly. Now we
integrate them right on top of the roof at the same
angle,” says Wolfe. The panels also no longer have
to face precisely south and the roof does not have
to be at an exact pitch. “We can consider aesthetics
without sacrificing too much capacity.”
Types of Systems
The simplest type of photovoltaic system is a
stand-alone system. It is typically used off the
electric grid, is battery powered and produces DC
power. Hamilton has a $700 system that runs the
lights and electric fence for a horse barn on his
property. “That’s about as simple as it can possibly
get,” he says.
Off-grid photovoltaic systems are designed “to
create power that can be stored in batteries and
used at any time of the day whether the sun is
shining or not,” says Wolfe. Northern New England
has quite a few such installations because people in
these regions tend to live in more remote locations.
People living on the utility grid can install a
similar system with solar panels and a battery. They
can make solar power and use it when the utility
system goes down. Because a generator may not always
start, creates noise and can be a “dirty” source of
energy, a photovoltaic system “can actually be more
convenient,” says Wolfe.
Grid tie inverters or utility interface inverters
wire directly into an existing building’s electrical
system. “They look at the voltage and the frequency
of the incoming utility power and will change the
electricity coming from the solar panel to match the
utility’s electricity and feed it directly into the
building’s electrical system,” says Hamilton.
If the building at that point of time isn’t actually
using any electricity, the electricity would flow
backwards out through the electric meter and onto
the utility grid. This is called net metering. “It
allows you to push power out when you are making
more and then when you need more power than you are
making you bring it in from the utility just like
normal,” says Wolfe. He estimates that approximately
two-thirds of the systems Global Resource Options
sells in New Hampshire and Vermont are on grid.
Although photovoltaics are becoming more popular,
many contractors and sub-contractors are still not
familiar with the considerations involved.
Richardson, for example, notes that most homes today
are wired for large amperage needs. “The minimum our
electrician had done was a 200 amp system,” she
says. Her house, on the other hand, required only a
33 amp system.
The Cost of Photovoltaics
Photovoltaic systems require a huge upfront
investment, but keep in mind that there isn’t a
monthly charge after the system is in. The initial
cost of a system varies depending on the size of the
house and the family’s energy needs.
“If people are willing to live consciously, we can
put about a $25,000 to $30,000 system in a house to
provide most of their power,” says Wolfe.
Incentive programs, available in some states, can
also help reduce the cost of photovoltaic systems.
Thompson received $1,400 in incentives from The
Renewable Energy Resource Center, although their
funds have already been reserved for systems
presently being installed. Other states such as New
Jersey, one of the leaders in renewable energy, have
more incentives available.
“Our business is tripling every year. The culture is
beginning to understand that not all electrons are
created equal.”
One of the drawbacks of photovoltaic systems is that
the net payoff will not happen for years. “The
traditional economic payback is very long — I don’t
mean 10 years or even 15 years, I mean longer than
that,” says Hamilton. “Yet, you’re comparing the
payback of a nice, clean energetic electron with a
dirty, old, dinosaur electron. Our strong contention
is that the two have nothing to do with each other.”
Hamilton also suggests that people should not look
toward renewable energy or photovoltaics to lower
their electric bill.
“It is not a cost effective way to do that,” he
says. “What you have to do is become efficient
first. Once you are as efficient as you can
realistically get, it makes a whole lot of sense to
start replacing chunks of your energy usage with
renewables.”
The issue of payback quickly arises in almost any
discussion of photovoltaics. “Everyone wants to know
what the payback is on a renewable energy system. No
one asks that about a car — what’s the payback on a
Lexus when a Ford Escort would have gotten you
there? It’s really about lifestyle choice and what’s
important to you as a consumer of energy in today’s
society,” says Hamilton.
Wolfe agrees comparing choosing a photovoltaic
system to purchasing organic milk. “When someone
buys organic creamery milk it may cost more money,
but they do it for a reason — to support the local
economy, to support the body, to stop some of the
pollution from factory farming. The decision to do
solar is very similar,” he says.
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