For the basics of how to proceed, the Green Building Institute in Jessup offers classes. David Woolley-Wilson, executive director of the institute, said no one has asked about doing the job himself and added that he would voice his concerns if they did. To start, not every house is suited for solar.
"Some are perfectly appropriate, and some shouldn't bother," he said. "This isn't just about falling off the roof or getting electrocuted. If you don't know what you're doing, you could spend all that money and not qualify for a subsidy or not get the performance because you have too much shade."
The Zipps say their panels have exceeded expectations. They spent $43,800 - above the $20,000-$30,000 average, according to Aurora. With their grants and tax credits totaling close to $18,000, and thousands from selling electricity back to Baltimore Gas and Electric Co., they estimate the system will pay for itself in under a decade.
Costs for summer months had been the most expensive because the family has a pool, hot tub and air-conditioning. The August bill was $39, down from about $240 the year before. The December bill was $79, but most of that was for heating gas.
In total, since the panels began operating in April 2008, they have produced almost 10,000 kilowatt hours of electricity, or an average of about 500 a month (the average homeowner uses about 1,000). They also have kept 163,000 pounds of carbon dioxide out of the air (the amount created by burning more than 51,000 gallons of gasoline).
"I did it for the environment," Karen Zipp said. "We've got to stop getting so much energy from other countries and dirty sources. But I'm also very happy with our bills. I'm a believer."