Before Jeff Wilson even broke ground on the Deep Energy Retrofit (DER) of his 70-year-old Cape Cod home, he started planning for solar panels. This allowed time to apply for tax credits and incentives that essentially drove the cost of the $32,000 system down to $14,000. After solar specialists evaluated Jeff's property and estimated that a system would be 89 percent efficient given some minor obstacles such as trees — and uncontrollable factors like cloudy Ohio winters — the system was designed and installed.
Jeff wanted to capture the most sunlight possible and prevent the solar panels from overheating, which makes them less efficient. For this reason, he installed WeatherBond Pro Weld-Free TPO (thermoplastic polyolefin), a heavy-duty rubber roof that is white to reflect the sun. He rolled this roofing out (it comes in sheets) on the flat roof.
With some roof retrofits on the back of the house to raise the pitch to nearly flat (this catches more rays), Jeff put his house in a much better position to capture solar energy.
Jeff has space to expand the solar energy system if he wants. For now, panels take up one-quarter of Jeff's total roof area and are positioned on the back of the house where no one can see.
The solar panels are connected to an inverter in the garage that turns direct current (DC) energy into alternating current (AC) energy, which is the type of energy we use in our homes. No backup battery is required for this system, making it cleaner and more efficient.
The inverter is an expensive part of the overall solar panel system, Jeff says. His inverter is located in his garage and tied to a meter his utility company installs.
The inverter display gives Jeff statistics on energy generated and consumed. Here, the meter notes that 1,958 pounds of carbon were saved by using the solar panels.
A digital meter inside Jeff's home shows him at any given time how much solar energy his household used and how much extra was sold back to the utility company.
Jeff can visit SunPower's monitoring website to measure his solar energy production and usage. He can check the history of his energy production at any time. The site also provides interesting comparisons, such as the lifetime energy produced by the solar energy system and how much carbon that saves in terms of gas miles. The system can even be monitored on an iPhone or iPod Touch.