A residential photovoltaic system could be one of the best home improvement buys in today’s troubled economy — one that not only pays for itself, but continues generating savings year after year.
That’s what makes the technology attractive to homeowners who are willing to invest up front in a system that may take 10 to 15 years to pay for itself.
University of Arizona physicist Alex Cronin is one of about 1,000 early adopters in Tucson who have taken this long-term view.
Cronin’s 2-kilowatt system includes 12 solar modules, an inverter that converts DC produced by solar cells to AC for household use, and a net metering system that lets Cronin sell electricity to Tucson Electric Power when the solar panels generate excess power.
Still, economics wasn’t the driving force in Cronin’s decision to buy the $6,000 system, which actually cost $15,000 but dropped to the lower price with a TEP rebate and federal and state tax credits.
While some homeowners might build a luxury kitchen or buy an expensive car, “For us it was the whole idea of investing in sustainability,” Cronin said.
Instead of making this a do-it-yourself project, Cronin hired Technicians For Sustainability to do the work.
“The installers have a lot of practice doing this, and when I saw them selecting their hardware, I was really glad I had them do it,” Cronin said. Instead of multiple trips to the hardware store and several weekends on the roof, Cronin got a turnkey system installed in three days.
The company also handled the building permits and documentation needed for the TEP rebate and tax credits. Cronin assigned the rebate to the contractor and paid an additional $9,000. Then, a few months later, he claimed the tax credits, which cut the final cost to $6,000.
Cronin’s solar panels have produced more than 5,500 kilowatt-hours of electricity since November 2007. During the cooler winter months, when the panels produce more energy than needed, the excess is pumped into TEP’s grid. TEP keeps track of the difference and credits Cronin with that energy during the summer months, when TEP power is needed to handle the extra load from a central air conditioning system.
While it’s possible to build a system that would satisfy peak demand, this usually isn’t a wise investment, said William M. Henry, principal services engineer for TEP. Homeowners usually figure their peak load and then install a system with about 70 percent of that capacity, he said.
At the end of the year, TEP zeros out the meter. If a home generated more electricity than it used, the company pays the wholesale price for the power, Henry added. But it would take long time to recoup the cost of the extra solar panels — which are not needed many months of the year — at wholesale prices.
Cronin’s electric bill totaled $686 for 2006, the last full year before the system was installed. In 2008, his bill was $159, amounting to a savings of more than $500 per year.
He originally figured on a 13-year payback period, but installing the system has made Cronin and his family more energy-conscious. They now unplug computers and appliances to shut down the trickle of electricity some devices consume even when turned off. They also added insulation to their refrigerator and have taken other conservation measures. Cronin now figures the system will pay for itself in 10 to 12 years — maybe sooner if energy costs rise.
While the lower bills are great, Cronin’s family is even more delighted about lowering its carbon footprint. A scroll through the inverter screen reveals that the system saved 3.578 tons of carbon dioxide that a coal-fired plant would have pumped into the atmosphere while generating the same amount of electricity.
That’s tons of carbon dioxide, weighing more than his Toyota Prius, Cronin said. Actually the amount of carbon dioxide produced would have been larger, he added, because some additional electricity would have been lost along the transmission lines linking his home with a remote generating station.
Cronin’s system is warrantied for 20 years, but current research shows polycrystalline silicon cells degrade by only 0.5 percent per year, he said. “That means after 100 years, they still might produce 60 percent of the power they make today.”
Given that scenario, paying for the system in 10 years and realizing substantial savings on utility bills for decades afterwards might just be one of the soundest investments around these days, Cronin observed.
To learn more
For more information on the TEP rebate and residential power systems, visit TEP’s Green Energy page at: http://www.tep.com/Green/Home/Solar">www.tep.com/Green/Home/Solar. This page links to a list of solar installers.
For information on tax credits, rebates, installers and other aspects of residential solar systems, go to Congresswoman Gabrielle Giffords’ page at http://giffords.house.gov">http://giffords.house.gov and click on “Legislation,” then on “Arizona Issues” in the sub-menu below “Legislation.” From there, click these links on the following pages: “Solar Energy,” “Solar Information,” and “Solar Power on Your Home: Getting Started.”