Photovoltaics: Lots of power on the roof

Posted Aug. 20, 2010, at 10:27 p.m.
Last modified Jan. 29, 2011, at 12:47 p.m.

If you check out the Efficiency Maine website, there is a section that has annual reports about solar installations in Maine: www.efficiencymaine.com/documents-services/reports#solar.

It is interesting reading for anyone who is curious about what kinds of solar projects are being installed in Maine and what they cost the consumer.

It might not be an exact accounting of all systems in Maine since the Efficiency Maine programs would only represent systems that have tax credits that are being paid to state residents.

I usually look at the solar thermal data since that is the area that I am most interested in.

As of late, though, I am intrigued by the installation of solar electric systems, which are known as photovoltaics, or PVs.

PVs are the darling of many folks because they cut that nasty electric bill down or in some cases completely eliminate it.

PVs have been rather pricey and have been either for wealthy, environmentally motivated investors or for those who live way off the beaten path and find it less expensive to install an off-the-grid system than to install electric lines.

But things are changing. There are a number of manufacturers that are offering PV panels at costs that are half what they were only a couple years ago.

This will help increase the number of new residential systems.

I believe the need for tax credits could be eliminated since these costs are dropping so significantly.

There are a couple issues to consider if and when you consider this energy-saving option.

There are certified solar PV installers, which is a good thing. Their presence on the job, however, does not pre-empt the need for a licensed electrician. PV systems, which are getting larger as the cost drops, can generate very large amounts of energy on sunny days. Some single panels, which seem ecologically friendly and be-nign, can produce enough power to kill a person in the wrong situation.

If we multiply a single panel by ten or twenty times, we have a lot of power on the roof.

Many PVs have built-in wiring systems that allow simple plug-in installation. As these systems get larger, it is imperative to make sure that any installation is completely inspected by a licensed electrician as well as your local electrical inspector.

Some of this stuff can be new and unique, and good basic electrical design is always important.

There have been some interesting issues associated with the installation of these electric generating systems.

There have been several reported instances of firefighters being shocked by PVs that are on burning homes.

It is not likely that a fire would be caused by the PV system, but if there is a lot of water flowing on a burning house and it is a sunny day, there is the possibility of a shock hazard.

PVs will produce power whenever sun shines on them. Even if the system is shut down, there is still power that can be delivered at the outlet of a panel or grouping of panels. Large amounts of flowing water can create a path for electricity to flow.

This is where proper design is imperative.

In some of the cases where the firefighters received non-life-threatening shocks, the decision was made to let the house burn down rather than risk electrocution of firefighters.

I believe that PVs will become a mainstay of our electric power mix this century.

The good feelings and energy savings cannot mask the importance of licensed installers who use proven, safe practices.

Once again, ask the right questions, ask to see the licensed professional electrician on your project and check references. Also ask about the longevity and long-term maintenance required for the system.

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