Editor's Note: John Patrick, Rebecca Selove's husband, contributes to Rebecca's blog series.
Our home was built for solar power. Built on the hillside facing due south, this home was designed to collect solar energy in many ways.
The home faces south and allows for maximum sunshine. Drawing By Mark West.
The farmhouse's roof was pitched to allow full sun for passive solar heating in the upper and lower levels during the late fall, winter and early spring. Large windows on the south side allow sunlight in to warm the dark tiles and stained cement floors. In the late spring, summer and early fall, when keeping cool is a priority, that same pitched roof shades those windows and floors.
We also tilted the roof to match the middle Tennessee latitude for maximum solar exposure for our installed solar panels. A photovoltaic system is beginning to make more environmental and economic sense because it provides renewable energy for the home and will probably decrease our electric bill by 60 percent. Our 5.17-kilowatt array connects to the grid so that when we are collecting more solar energy than we are using, the excess energy goes on to the grid for use by others—probably by our neighbors. With incentives from the Tennessee Valley Authority, our excess energy will earn 12 cents more than the prevailing rate of approximately 9 cents per kilowatt. Currently, that means we’ll receive 21 cents for every excess kilowatt we produce.
Solar panels provide electricity to the home and solar thermal panels heat the home's water. Photo Courtesy John Patrick.
Tennessee Valley Authority values stable sources of renewable energy and guarantees this contract for 10 years. At this rate, the estimated payoff for our system will be 10-12 years. We think that in a carbon-restrained world with carbon taxes or a cap-and-trade system, those rates will increase and reduce that payoff time.
Two solar thermal panels to provide our hot water. Feeding into an 80-gallon tank that will retain hot water for 36 hours, this system will potentially cut our hot water electricity usage in half, which for an average household, is the largest annual use of electricity. For those cloudy winter days when sunshine is at a minimum, an element within the tank will heat the water. The hot water system will get a boost from our geothermal heating and cooling system. That system takes advantage of the constant temperature of the earth to heat and cool our home, and in the summer it provides us free hot water by the use of its de-superheater option that uses the hot air to heat our water. In total, with the Tennessee Valley Authority payback, the de-superheater and the solar panels, we should have a payback period of 10-12 years—again, that is at today’s rates.
Although economics is integral to the ultimate wide-spread acceptance of solar power, shifting to renewable power is a move we are choosing to make to lessen the impacts of climate change. We hope our home can be an example of what is possible.