BY KATE REYNOLDS
PHOTOS BY MATT ROSE
ILLUSTRATION BY RIMAS ZAILSKAS
Energy costs and the cumulative effect of carbon emissions on the atmosphere are major concerns for everyone these days. It isn’t theoretical — these issues raise practical challenges for earth-conscious homeowners. We’d love our dwellings to be more energy efficient and environmentally responsible, but where to begin?
According to Dave Hollister of Sundance Power, a 13-year-old solar power systems company in Weaverville, we just have to look up. The ever-present glow of the sun is the simplest way to meet our energy needs and be part of the global solution in the bargain. Solar power, the ultimate renewable energy, can turn green technology into gold.
1. Two Powers in One
Solar power can be accessed in two ways: the photons in sunlight can be converted into electrical power, or the heat of the sun can be collected as thermal energy. Although they require discrete mechanisms for their utilization, individually or in combination the systems can reduce your home’s "carbon footprint," lower your energy costs and, in some cases, actually produce a net financial gain.
2. Photo Op
Photovoltaic (PV) cells harvest sunlight via multiple modules linked together into panels or arrays. Photons are absorbed into wafers of silicon within the modules, which act as semi-conductors, knocking electrons loose from their atoms and gathering them as direct current (DC) electricity. Since most household appliances run on alternating current (AC), a PV system requires an inverter, which converts the current for domestic use or for flow into the utility grid.
3. Some Like it Hot
"Solar thermal panels consist of a series of fluid-filled copper tubes with a black-coated absorber plate that takes in the sun’s energy, converts it directly into heat, then transfers the heat into the fluid," says Hollister. This heat then can be integrated into domestic hot water systems, as well as radiant floor or forced-air heating systems.
"There’s another type of solar collector that takes the heat and passes air over it, so you’re heating it directly, like a passive solar house would," he adds. "In this case, you’re creating a sort of mini-greenhouse that sits on your roof, circulating air and heating the house."
4. Location, Location, Location
In order to harness the sun’s bounty you have to be exposed to it. Heavily wooded or shaded settings are impractical, for obvious reasons. "The optimal site for a residential system is on the roof of the home, with a southern facing orientation." says Hollister "The roof is really the best place for a solar thermal system, but PV systems can be mounted on the ground as well. They’re very versatile that way." To maximize collection, PV arrays can even be outfitted with tracking systems, which angle the panels to follow the sun’s arc through the sky.
5. Going it Alone
"Typically, there are two main motivations for installing renewable energy electrical systems in your home," says Hollister. "Some people want to become more self-reliant, to have a sense of autonomy or an independent lifestyle. Others want to use renewable power because they want to be part of the solution. They’re not really worried about having power when nobody else does — they want to take action within their own lives to participate in sustainability."
For those who would prefer to be, literally, "off-the-grid," the system requirements include a battery to store power for times when the sun isn’t shining. A battery-based stand-alone system consists of a solar array, a charge controller to prevent the array from overcharging the battery, the battery itself and an inverter.
"With a stand-alone system, you really have to design to meet your energy budget," Hollister cautions. "You have to be conscious of how much energy you are collecting and storing and how much you’re using."
6. Staying Connected
Generally speaking, grid systems are simpler, more efficient and cost less. They consist of an array and an inverter, with the power delivered directly to the home and utility system. "The only downside," notes Hollister, "is that you don’t have any stand-alone capabilities, so if the grid goes down, you go down." There is another option, however. Battery systems can also be configured to be grid interactive.
7. Power Broker
A PV system can potentially produce more electricity than you need, in which case you may be able to sell it to your local utility. There are several ways to do this. One is "sell-excess" mode, in which the meter on your house measures current in both directions. You are charged the retail rate for what you’ve consumed and the utility pays an avoided cost rate for the power that you sell to them.
"Sell-all" is where you sell the power off the array directly to the utility and then buy it back from them. "From a financial standpoint, that’s the preferred way to design the system because you not only sell the electricity — that’s worth between 3¢ to 4¢ per kilowatt hour, depending upon whether it’s peak or off peak — but you can also sell the RECs — the Renewable Energy Credits — which are associated with clean power," says Hollister. "In North Carolina right now, the RECs are worth anywhere from 15¢ to 18¢ a kilowatt hour, four to five times more than the electricity."
8. Bang for the Buck
Electricity may have star quality, but solar thermal is no slouch on the budgetary — or planetary — front. "Solar hot water is probably the single most important technology that we can personally implement for offsetting the effects of global warming and climate change overall," says Hollister. "The systems are very reliable, affordable and, amortized over the years, they put cash in your pocket. They potentially have double digit returns, with a simple payback within a few years."
The big payoff, however, is that a typical solar hot water system will, over its lifetime, displace up to 71.5 tons of CO2 if replacing an electric system, and up to 10.5 tons of CO2 if replacing a natural gas system. "This is the most widely used solar technology in the world," Hollister emphasizes. "It’s the low hanging fruit of renewable energy."
9. The Bottom Line
So what will it cost? Upfront, the investment can be substantial, with solar thermal starting at $5,000 for a simple hot water system and averaging in the $10,000 to $12,000 range for a heat and hot water combination. PV electric, says Hollister, is much harder to average.
"PV is very scalable," he explains. "These systems can be designed for a few thousand dollars to hundreds of thousands of dollars. Your investment level can be based on an arbitrary budget. One nice thing about PV is that you can easily start a system and then add panels over time, so we encourage our clients to look towards the future."
10. Take Credit
While the initial outlay for going solar may seem a bit daunting, both the state and federal governments offer substantial tax incentives to encourage homeowners to be clean and green.
"Here in North Carolina there is a 35% state tax credit available, so for each thousand dollars you spend on your system, you can get $350 back. That’s a credit, not a deduction. That’s real money. In addition to the state tax credit, there’s also a federal tax credit of 30%." There are caps for both, but, as Hollister points out, "an investment of $10,000 could take $5,500 off your tax liability."
As with any other major improvement to your home, it’s important to do your research and deal with reliable contractors. The system you buy should meet or exceed the specifications for federal and local code compliance, but it should also be designed to realize your vision — your short- and long-term needs. A site-and-load analysis is vital to creating the most efficient system. "There are so many options. There really isn’t a one-size-fits-all approach," says Hollister. "Ideally, it’s a collaborative process."
It could also be a step towards a brighter future, on both a personal and global level. Here comes the sun.
