Rays That Pay
On a windy April afternoon just a few days before Earth Day, the power company flipped the switch to connect our “plant” to the grid, and our indoor wireless monitor began tracking electricity production. By the end of its first full month in operation, our system had produced more than 800 kilowatt-hours of electricity, about twice what we used in that period, according to our meter. Unlike the installation, our solar electric system works silently, except for maybe the occasional “creak” when the modules and their racks expand or contract in changing temperatures. It also works without emitting carbon dioxide, sulfur, mercury, or other pollutants into the atmosphere.
The electricity our panels produce flows into the existing power grid through a net meter, which is counterintuitive: The meter advances when we use more than we create and reverses when we make more than we use, resulting in “net” electricity production. If we had an off-grid system, the excess power would be stored in banks of batteries. Because our photovoltaic system generates electricity only when the sun is out, there’s a need for either a connection to the existing grid or battery storage for nighttime and cloudy days.
The industry got its start with off-grid applications, says Bella Energy’s Welch, who began with vacation cabins and ski huts back in the early 1980s. But he says systems like mine, called grid-tie, are far more popular today, mostly because they don’t use batteries, which can boost the dollar cost of the system by as much as a quarter.
Batteries also increase the environmental cost: They contain lead and other heavy metals, and they must be replaced every 10 years or so. Welch points out that the photovoltaic modules, on the other hand, pay back the energy inputs of manufacturing in only about two years of electricity production. And the modules last for decades. “We have systems we put on roofs 30 years ago,” he says, “and they’re still working today.”
“We think grid-tie is the way to ‘green’ the existing power grid,” says solar pioneer Leigh Seddon, vice president for engineering at Alteris Renewables, the largest solar electric system installer in the Northeast, “to reduce reliance on nuclear and fossil-fuel power plants.” Off-grid systems, he says, make the most sense in remote locations, where the cost of getting electricity to the site can soar to as much as $75,000 a mile.
What if you don’t live in a sunny climate? Even in Vermont, which, according to Seddon, is the second-cloudiest state in the nation (only Washington State has more overcast days), the average south-facing roof receives 100,000 kilowatt-hours of energy in a year. “If you tap that at 15 percent efficiency, the average for photovoltaic modules,” he says, “you end up with 15,000 kilowatt-hours per year, or nearly twice what the average Vermont family uses.” (Washington State isn’t out of the photovoltaic picture entirely; the sunny climate east of the Cascade Mountains is ideal for generating solar electricity, and even western Washington, where the rain falls and most of the state’s people live, has potential.)
If you have sticker shock but still want long-term financial and environmental benefits, look for a lease-purchase program. For a small down payment, you lease a system from a company that contracts for installation and maintenance. “You save money almost from the first month,” says Seddon, “and it removes the risk of finding a good installer.” In most cases, you have the option to buy the system at a lower price over time; the leasing company takes the tax credits and depreciation.
“This is the biggest revolution in the residential portion of the industry,” Seddon says, noting that this year residential sales are on track to increase because of leasing systems and higher electricity costs. Another trend to watch, he says, is that towns and public utility districts are beginning to offer low-cost loans for energy improvements like photovoltaic systems.
For less than $6,000 you can simply consider heating about two-thirds of your household water with a solar hot water system (also known as solar thermal). Solar thermal systems absorb the sun’s heat energy to use directly for heating water, and they are about 40 percent efficient, says Seddon. What’s more, they can attach to your existing hot-water heater tank, which, depending on the water heater’s size and your consumption, can account for as much as 20 percent of your power bill.
Cheaper “thin film” technology, made from microlayers of silicon, holds promise for lowering the price of overall photovoltaic systems even further, says Welch, and can be used in products like roof shingles and paint. But they are only half to two-thirds as efficient as current technology at converting the sun’s energy into electricity, and thus require one and a half to two times as much space to produce the same amount of electricity.
Richard and I invested in generating our power from the sun because it made financial sense and it aligns with our environmental values. What we weren’t expecting was for our investment to come with a membership in a fraternity of green gearheads. As soon as the panels went up on our roof, strangers knocked at the door to ask how we liked our system and to share tips from theirs. We felt like Harley riders acknowledging one another with a secret hand wave as they roar down the highway.
We also didn’t realize how good it would feel to tally the amount of CO2 we’ve prevented from entering the atmosphere (171 tons in just two years—the equivalent of taking 31 cars off the road). We watch the wireless monitor in the living room that shows our current power output and daily total the way some people keep an eye on CNN, and when we’re away from home we check the website to see our numbers.