| Not everyone has the space, skills or dollars to go 100% solar, but Jim Evans of Republic made the commitment in 2010. His impressive array of solar panels is now producing 128% of the energy needs of the residence.
Here’s the story of this do-it-yourself energy-savings champion.
 The project at his rural property near Republic was a natural. Jim and Terri had built their better-than-average energy-efficient home in the 1970s but always wanted to do more. After extensive research, Jim decided to incorporate solar and to provide a cost-effective practical demonstration project for southwest Missouri. The result is an integrated system that incorporates an energy-saving design, energy-efficient construction and improvements, the use of solar thermal collectors for hot water heating and a large photovoltaic array for electricity production.
The home is classified as total electric because the only utility hookup is electricity through Empire District Electric. Sewer is a septic system that uses a large lateral field. Water is provided by a 640-ft. deep well on the property. A small propane space heater is available for emergency heat but is not used regularly.
Design and Efficiency
Jim said the project started with attention to an energy-saving design. He started with an architecturally efficient shape that has maximum space for minimum surface approximating a cube. That combines with one of three floors below ground, 75% south-facing sun exposure with seasonally appropriate overhangs, 6-inch thick walls with studs 24 inches on center, a large south-facing roof with 57-degree pitch appropriate for maximum winter heat collection, north and west wind break, air-lock entries at every door, an attic designed to use the chimney effect for summer heat expulsion and large interior thermal mass.
Energy efficiency elements include fluorescent lighting throughout, all rooms with access to sunlight, energy-star appliances, an efficient heat pump, minimal air leakage, thermal-pane windows, oversized wiring and the elimination of phantom electrical use.
Three years ago Jim installed 160 sq. ft. of solar thermal collectors on the roof. He explained that an ethylene glycol solution is circulated through these collectors to transfer heat to a 500-gallon tank in the basement. The water in the tank stores heat from the sun for hot water heating. The system uses a SunEarth controller. Most days the system operates only a few hours to restore the heat lost to usage and thermal leakage.
“Nearly 100% of our domestic hot water is supplied by this system,” he said.
In 2010, Jim added an 8.4 kW grid-tied photovoltaic array. It incorporates 140 Kaneka G-SA060, 60 Watt Thin Film Solar Panels connected to two 4.2 kw Solaria brand utility-interconnect inverters. He purchased the system from Wholesale Solar (Mt. Shasta, California) and had it shipped by Con-Way Freight to Republic. Because the nearly 1,600 square feet of south-facing surface necessary for the array exceeded the available roof space of the residence, a post and beam structure was constructed 80 feet south of the house on which to mount the panels.
Cost and Results
The total installed cost of the photovoltaic array after federal tax credits was under $19,000. Those tax credits expire at the end of 2016 and cover 30% of the cost, with no upper cap. The accompanying chart compares the actual electrical production with the predicted production and actual consumption for one year.
Black = Predicted production based on size and average daily insolence, 10,800 kWh
Orange = Actual power produced by the array, 12,800 kWh, $1,375 value
Green = Total power used, 10,000 kWh, $1,075 value
The original plan was to install a net-metered PV system that would supply between 80% and 90% of our annual usage. But two things happened:
- The array exceeded production by almost 20%
- The energy efficiency of the home increased by about 25%
“As a result, the array has produced about 128% of the energy needs of the residence. Through the net-metering agreement with the utility we receive credits, at a very low rate, toward future electrical needs,” Jim said.
Summary
“Our plan for the near future is to buy and electric car that will add a little more than 4,000 kwh per year to our usage and add another small solar array to our roof so that we can generate about 90% of the power we need for both our house and most of our driving," Jim said.
The PV array provides a return on investment of more than 6% per year in energy savings. With average increases of 5% per year in utility costs, Jim expects it to pay for itself in 10 years. The addition of the electric car to the mix will double the ROI and decrease the payoff time to around seven years. These calculations do not include the cost of energy efficiency improvements, the solar hot water heater or the purchase price of the electric car.
Credits
“I acknowledge the advice and assistance of Randy Branson (Branson Electric), Josh Rice (WholesaleSolar.com) for helping me purchase an appropriate grid-tie system at an excellent price, and Korina Branson and David Jones (Greenstick) for an energy audit and making energy-efficient modifications t o our home.” – Jim Evans
|
ONE Spotlight
Jim and Terri Evans
Republic, Mo.
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Installed 2010
Produces 128% of energy needs of residence
Suppliers and Sources
WholesaleSolar
www.wholesalesolar.com
800-472-1142
Greenstick
www.greenstick.com
417-766-1441 - Springfield
417-335-0009 - Branson
|
