Solar cells, or Photovoltaic (PV) modules, date back to the 1950s. From small, low-output, direct-current curiosities powering watches, calculators, and children’s toys to productive, higher-output sources of practical AC electrical energy to the homeowner, solar harvesting may soon be coming to a home near you.
 Research and development stimulated by NASA’s need for renewable energy in space has produced an alternate energy source whose time has come, especially for the homeowner with some basic carpentry and electrical skills. In the ‘60s and ‘70s, PV systems provided a way to match the electricity they generated to the electricity provided by the electric utilities. At first, this was done by a device called a Central String Grid-Tie Inverter. Ranging in size from a waste paper basket to a desk, the Central Inverter was expensive, and therefore had a longer payback time. It lacked reliability, brought dangerously high DC voltage into the home, and required an MIT graduate to design and oversee the installation of the system. If one of the solar panels failed, the entire system failed, much like the old series holiday tree light sets. Today, new technology has emerged that has changed everything.
Enter the Grid-Tie Micro-Inverter.
One of these, generally as large as two paperback books, is attached and connected to each solar panel, changing the output of that solar panel to alternating current, matching the electricity generated by the utility company without the need for a central inverter. For more information, visit www.enphaseenergy.com/ products/index.cfm.
Why is this important? Glad you asked. Since the central inverter is no longer needed, the price of the system is reduced, in many cases by $1,000 or more. The micro-inverter installer needs only to follow some basic rules for the system to operate correctly. The engineering has been done by the manufacturer, allowing the installation to be done by the homeowner.
Not comfortable working with household electricity? Good news! Any qualified electrician has the expertise to connect this equipment to your home’s electrical system, and it shouldn’t hurt the pocketbook too much, either.
Watch the video on YouTube: www.youtube.com/ watch?v=hJPXsN_gFz8. If one of the solar
modules should fail, although possessing an expected lifetime of 100 years, the remaining units continue to produce electricity.
Don’t have a lot of money to install a large system right now? No problem. Install the roof racks and electrical wiring to your home’s electrical panel. Install one solar module and you can add an additional solar module when you find it affordable. Just clip another panel on the rack and plug it into the harness. Done! When your system reaches the capability of supplying more than your electrical energy needs during daylight hours, your electrical meter will actually run backwards, crediting you for supplying electrical energy to the utility company.
Interested? First, a few details...
Your utility company will want to know that your system has been inspected by a qualified electrical inspector. There is an application to submit with a $100 fee. When it is happy that your system is in compliance with what it requires, it will install a new meter, and you will be harvesting power from the sun. The equipment I suggested in this article should meet the standards of the utility company servicing you.
Today, a solar system capable of producing one Kilowatt (1,000 watts) would cost about $3,500, less a 30%
tax credit. For more information, visit www.energystar.gov/index.cfm?c=tax_credits.tx_index.
In Northeastern Pennsylvania, we can reasonably expect an average of 186 days of solar harvest per year. If we assume eight hours of generation per day, that indicates 1,489 hours of electricity production per year, or 50 hours of production per month. If you would like to see all the calculations and graphs, visit NASA’s website at eosweb.larc.nasa.gov/cgi-bin/sse/grid.cgi?uid=3030.
How much can you save? This is really difficult to predict, but let me put it to you this way: You and your neighbor are sitting in his backyard on a nice, sunny Fourth of July, enjoying one another’s company. Your neighbor has the system described in this article, but you don’t. At home, your refrigerator is running, and maybe a few other small items. You are literally buying your electricity from your neighbor.
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