Matt and Kelly Grocoff just received the March/April utility bill for their 110 year old Folk-Victorian home in Ann Arbor, Michigan’s Old West Side Historic District. It was -$68.64—and yes, that’s a minus sign before the dollar sign. Matt and Kelly’s home—America’s oldest net-zero energy restoration and Michigan’s first net-zero house—has been retrofitted so that it produces more energy than it consumes.

Matt and Kelly use 10,000 kilowatt hours of energy per year. Their 8.1 kW SunPower solar panels (which cost them $19,000—less than an SUV—after a tax credit and utility incentive) supply that and more—enough to earn them money back from the local utility and charge an electric car for 10,000 hours of driving. Kelly and Matt expect to earn about $1,400 by selling energy back to the community grid this year.

Kelly, a clinical therapist, and Matt, the host of Greenovation.TV, say that buying their 2,200-square-foot home—complete with drafty old windows, lead paint, zero insulation, a 50-year-old furnace, asbestos siding, a gas-powered mower in the shed and even a few pieces of coal scattered around the back yard—was a dream come true. Their goal was to turn the historic home from an energy hog into an energy producer because, Matt says, “130 million existing homes are consuming 22 percent of the energy in the United States. And if we built every new house to be net zero, but we neglected our existing homes, we would reduce our carbon output by zero.”

In addition to installing solar panels, the Grocoffs improved their home’s windows, added weatherstripping and installed a geothermal heating and cooling system. Those fixes, plus careful living, have reduced the home’s energy load by 70 percent—and all the while the Grocoffs have kept the National Trust for Historic Preservation folks happy. “This is not a gut rehab or a pre-recession large-scale remodel,” Matt says. “This is an affordable and practical restoration that we hope is an example for others to follow.” You would never know the Grocoffs’ All-American home with the classic front porch is “green”—until you get a glimpse of the solar panels blanketing the south-facing roof.

Matt estimates they will eliminate $77,400 in energy costs over 20 years and receive more than $27,000 in renewable energy credits from their utility company. “That’s a $104,000 return that we will keep in our community in Michigan to help restore our economy,” Matt points out. Because energy efficiency and renewables have a guaranteed return, “Kelly and I believe it’s the safest place to put our money,” Matt says.

“Did we mention that our house is also the most comfortable house in the neighborhood?” Matt adds. “We want to show everyone how cozy saving civilization can be.”