Homeowners have often dreamed of small-scale devices that can be installed on their roofs to provide all the energy needed for the operation of their household. That day has arrived. New options in wind and solar energy generation can generate enough kilowatts of power to net meter whole houses and enhance an electrical contractor’s ability to penetrate the residential alternative-energy market. In fact, small wind turbines and solar photovoltaic (PV) panels are often complementary technologies that can be used together as a hybrid system to offset the variability of both natural resources.
Additionally, electric radiant heating has gained awareness in North America as an energy source that uses electricity efficiently. While hydronic radiant systems, which circulate hot water through pipes installed under subflooring, are more common in the United States, proponents of electric radiant systems say significant opportunities exist to supplement conventional heating sources and become a primary source of residential heating in the future.
These alternative-energy sources join the technology of geothermal heat pumps, which are also referred to as ground source heat pumps. The renewable-energy source transfers heat stored in the earth or in ground water into a residence during the winter, and during the summer, it transfers the heat out of the structure and back into the ground. A new report from the Geothermal Energy Association shows a 25 percent increase in private-commercial projects since August 2008, with 126 projects under development throughout the country, and with the potential to put 5,500 megawatts of new geothermal power online. This trend may extend to residential growth as well.
In other recent developments, the U.S. Environmental Protection Agency announced new requirements for residential geothermal heat pumps, allowing water-to-water geothermal heat pumps to earn the Energy Star label. Units that meet the stricter standards are projected to be up to 45 percent more efficient than conventional ground source heat pumps.
Out-of-the-box solar solution
Ready Solar is re-engineering the way small PV systems are installed with a modular, preassembled product that simplifies installation for residential applications compared to a traditional PV system. Resembling skylights on a roof, a Solar in a Box system consists of two individual alternating current (AC) solar panels, measuring 6 feet, 5 inches, by 6 feet and weighing 120 pounds. Each 0.4 kilowatt (kW) peak power system includes two direct current (DC) to AC microinverters and associated hardware required for installation and system monitoring. The systems are available through electrical distribution.
Up to seven Solar in a Box units are wired to a two-pole, 15-amp breaker; larger systems require additional breakers. The grid-tied units are not wired into batteries and will automatically shut down and restart in the event of a power outage. Internet-based panel monitoring allows system owners and installers to monitor the production of each panel in real time, eliminating the need for any unnecessary service calls.
According to Aaron Bingham, Ready Solar sales and marketing associate, residential installations range in size from 0.4 kW to 15 kW.
“Our most common system size is 2.4 kW large, for an average 2,000-square-foot house,” Bingham said.
Bingham pointed out that systems are attached to rooftops using a standard shingle mounting block or a new ground-mount installation option.
“Each of our proprietary mounting options is designed to be minimally invasive and requires up to 70 percent fewer roof penetrations than traditionally installed systems,” Bingham said.
And the cost of one power unit? “The cost of a unit varies depending on quantity purchased. Systems should cost installers between $4.50 and $5 per watt,” Bingham said.
The Solar in a Box concept developed from a need for a more standardized approach to solar power installation.
“New-to-solar installers often find the traditional solar business model very daunting, and established installers will sometimes turn away small jobs because they still require a significant investment of time to survey the site and design the system,” Bingham said. “Our preassembled product cuts installation time and costs in half, and installers who are new to solar technologies have minimal opportunity for error.”
Bingham also noted that Solar in a Box allows new installers a less complicated transition into the solar-installation market.
“Ready Solar is designed to be very easy for first time installers. We find that installers working on their first job can be in and out in a day with minimal training, assuming system size is less than 3 kW. In contrast, most traditional installations take at least two to three days, especially for inexperienced installers,” Bingham said.
Harnessing the wind for power
Large utility-owned wind turbines are beginning to dot the rural landscape in windy states, such as Arizona, California, Iowa and Texas. However, small-scale wind generators also are designed to catch the element we can’t see and spin it into utility gold. Properly called a “wind energy converter,” its rotor blade stops about 60 percent of the wind, which is converted into energy.
Sources at Flagstaff, Ariz.-based Southwest Windpower report that interest in residential-scale wind generators has been expanding in recent years spurred by a greater awareness of alternative-energy systems that can reduce electricity costs, generate surplus energy and potentially eliminate electrical bills.
“A residential-scale wind generator is a great option for people to take some control over these issues,” said Miriam Robbins, Southwest Windpower marketing manager.
Southwest Windpower manufactures the Skystream 3.7, developed in collaboration with the U.S. Department of Energy’s National Renewable Energy Laboratory. Company officials report it is the first backyard-sized wind turbine that includes a built-in inverter and doesn’t require external components.
Skystream 3.7 is a downwind, direct drive, permanent magnet wind generator typically mounted on a 45-foot steel pole. Designed for grid-connected homes and small businesses, the rotor blades are made of compression--molded fiberglass and have a 12-foot diameter. The rated power of the unit is 2.4 kW and, depending on the wind resource, can generate between 30 to 80 percent of the power an average home requires.
“Because of its size, most of our customers are residential homeowners for the Skystream system. Typically, people need to live on one-half acre of land or more and have a wind resource of at least 12 mph average annual wind speed. We also see growing interest from commercial spaces, small businesses and municipalities,” Robbins said.
Skystream 3.7 is a grid-connected wind generator, and Robbins said that, while there is still a large global need for wind-energy systems in areas with no grid connectivity (remote homes, villages, monitoring sites), the company is experiencing “exponential” growth in grid-connected systems.
“These are people who have access to electricity through their utility and are looking for ways to become more sustainable and off-set their electric bills,” Robbins said.
Robbins pointed out that electrical contractors can apply their expertise to provide wind generator installation service.
“Electrical contractors are an essential part of the installation process. Most states require licensed contractors to make the connection to the grid. Southwest Windpower sells through factory-trained dealers and installers. Many of our dealers are electrical contractors. They see this as either a new business opportunity or an expansion to an existing home electric services business,” Robbins said, adding that “a fully installed system on a 45-foot tower is typically around $15,000 to 18,000.”
Despite the growing interest in harnessing the wind, the market is not without some barriers.
“The biggest obstacles are local zoning and permitting, which is different in every region. We have noticed positive inroads in communities through education, and installation of systems helps breed acceptance,” Robbins said.
Transferring radiant heat to local markets
Mention radiant heat to someone and they will likely respond by acknowledging it as “the mesh system” that can be embedded under tile flooring in spaces, such as kitchens and baths. However, advocates point out, electric radiant heat can not only supplement conventional home heating systems, but the technology is capable of heating whole homes even in the most frigid climates.
Residential radiant heat isn’t limited to interior applications. Driveways, walkways, roofs and gutters can benefit from electrical grids, cables, woven mats and panels that, rather than heating the air temperature, provide warmth by transferring heat from a warm surface to a cool surface.
Widely accepted in parts of Europe and Asia where electricity is the only utility available or the most efficient and affordable heating source, proponents say there is a wellspring of market potential for electrical contractors.
According to Lyle Moroz, vice president, electric heating division of Danfoss Inc., North America, the biggest obstacle to the concept in the United States is awareness.
“Although there is a wide range of installers, including electrical contractors, plumbing/HVAC contractors, even tile installers, at Danfoss, we believe the electrical contractor is in the best position to install these systems. It’s a great business opportunity for these contractors. It’s a sizeable market, and even with the current economic downturn, is well poised to continue to grow in double digits,” Moroz said. Moroz said there is a general perception that electric heating is expensive.
“There was a time when electricity heating costs were much higher than similar natural gas costs, but this equation has changed dramatically in the last 10 years. Also, many jurisdictions are implementing time-of-day pricing, which makes electricity costs much cheaper overnight, often less than the daytime rate. Taking advantage of these prices using thermal storage principals, can make electric radiant heating much less expensive than gas or oil,” he said.
MCCLUNG, owner of Woodland Communications, is a construction writer from Iowa. She can be reached at firstname.lastname@example.org.