Rountree Architects - Articles, Connecticut, Vermont, Solar Architeture, Home Builders, Designers, Green Energy

The Sun Also Rises-- Again
After decades of setbacks, solar energy returns and many believe that it's here to stay.

The dream of solar energy and what it implies--cheap power, clean air, independence from foreign oil producers--has been around for a long time. But now, the dream may finally be coming true. Solar electricity, also called photovoltaic (PV) energy, is fast becoming a viable option for homeowners who want to generate their own power. A technology developed to power satellites in the 1950s, PV energy had been too expensive for most residential applications until recently. Concerns with rising energy costs, power disruptions, pollution and global warming have combined with reductions in the cost of PV cells, improved technology, government incentives and solar-friendly legislation to make solar power shine brighter than it has for decades.

Although the U.S. solar power industry went through hard times in the last 25 years, it didn't die. Instead, it retreated to overseas markets. In recent years, more than 75 percent of American-produced solar cells--the key component of a PV system--have been exported. Some went to developing countries where photovoltaic systems are used for lighting, powering telecommunications systems, and pumping water for crop irrigation and domestic needs in remote villages. Others went to industrial countries, especially Japan and Germany, where there are strong incentives to put solar electricity (and solar hot water) in homes, schools, and commercial and municipal buildings. As the technology improved, the solar industry began to find niche markets in the United States, including traffic control and message boards, TV, radio and cellular repeater stations, and navigational buoys and beacons. Add it all up and you have an industry approaching $4 billion in global sales.
By all accounts, PV energy won't stop there.

Allen Barnett, chief executive officer of AstroPower, a fast-growing producer of solar cells and solar electric power systems for residential applications, says that the PV industry is growing by 25 to 30 percent a year. AstroPower's capacity is growing faster to keep up with demand. Plant expansions have brought the company's production capability from 35 megawatts in 2000 (a megawatt equals 1000 kilowatts, enough energy to power hundreds of homes) to 110 megawatts projected by the end of 2002--a total that would have been unthinkable just a few years ago.
John Schaeffer, founder of Real Goods Trading Co. (now called Gaiam Real Goods after a recent merger), has been selling solar products for more than 20 years. He confirms that the hot growth area today is on-site generation of electricity--either by solar or wind power. "Events such as Y2K, California's rolling blackouts in 2000, recent spikes in energy costs and ongoing unrest in the Middle East have spurred interest in self-sufficiency and have also spurred growth."

National homebuilding companies have become interested in adding PV to their homes' selling features. Shea Homes, the 10th-largest builder in the United States, and Pardee Homes are installing PV systems in hundreds of new homes under construction in various San Diego communities. U.S. Home, a division of Lennar Corp., plans to build more than 900 PV-energized homes in 2003 at its Bickford Ranch development near Sacramento.

There are cost efficiencies to integrating PV installations with the normal workflow of home construction, according to Jonathan Done, a spokesman for Shea. "We are able to offer buyers systems for $6000 to $10,000, depending upon the size, after Shea takes care of getting the state rebates," he says, "and the homeowner can take an additional 15 percent state income tax credit." By comparison, installations on existing homes typically cost 50 percent more. Home sales with PV have been brisk, Done says. "The feature certainly does not hinder sales, and may be helping."

In 2001, The Home Depot decided to offer packaged PV systems, pre-engineered by AstroPower, at select outlets in the San Diego area. The systems are sold under The Home Depot's Installed Products program. If sales go well, PV products may be rolled out to as many as 70 Home Depot stores in California and eventually to other strong solar power markets across the country.

Net Metering
Another reason for the PV industry growth is "net metering," a protocol that allows homeowners to be credited for the electricity they produce. It works like this: When a homeowner produces more electricity than he or she is using--typically during the middle of most weekdays when usage is low--it's fed back into the power grid. In this reverse mode, the homeowner's analog electric meter literally spins backward.
When usage outstrips production or when the sun sets and rooftop electricity can no longer be produced, PV homeowners draw from the utility company. But PV homeowners on the net-metering system pay only for the net amount of electricity they use. In effect, they are being credited for their production at the same retail price they would normally pay the utility company. In states with tiered electric rates--where homeowners pay a higher rate per kilowatt once their usage surpasses set thresholds--the credit pays for the most costly kilowatt-hours.
In the dozen or so states where net-metering legislation has not been enacted, homeowners may still connect to the grid but they won't get credit for their excess daytime production. Instead they will have to store it in a bank of batteries. Batteries have been successfully used for decades, but they add expense, lower system efficiency, require maintenance and monitoring, and introduce hazardous chemicals into the home environment. To learn more about net metering in your state, visit www.dsireusa.org.

Another reason for the increasing interest in solar electricity is steep reductions in the cost of PV cells--the basic units from which PV solar modules are made. According to Barnett of AstroPower, the cost for PV cells is halved roughly every 10 years. Though manufactured from one of the most common elements on Earth, silicon, solar cells are not cheap. The retail cost is between $4.50 and $7 per watt of rated capacity, or about $600 for one 100-watt module. The cost is high because the conventional way of manufacturing cells is fairly complex. First, large silicon crystals have to be grown, typically in cylindrical forms. These ingots, or loaves, are then sliced with lasers into wafers of pure crystal before becoming the basis for a solar cell. Several companies have developed ways to lower cost and speed production of solar cells. They have, for example, found that it's easier and less expensive to grow multicrystalline, or polycrystalline, materials (masses of smaller crystals). These cells are nearly as efficient as those made with single crystals.

Other companies have experimented with thin-film technologies in which silicon material is vaporized and deposited in very thin layers on various substrates, including glass and flexible backings. These amorphous solar cells have opened the possibility for creating innovative products, such as electricity-generating windows, roofing and siding. While thin-film products are typically less efficient than single- or multicrystalline cells, they cost significantly less.

Two companies have found ways to produce multicrystalline wafers in sheets--a sort of hybrid between crystalline and thin-film technologies. These sheets eliminate the need for slicing the material into wafers and enable mass production of wafers. Evergreen Solar calls its process "string ribbon" because it produces wafers for solar cells by drawing molten silicon up between two "strings." The resulting modules are among the lowest priced in the industry. AstroPower's version of this process, called Silicon-Film, is a continuous-flow output of multicrystalline silicon wafers, and it has the potential to cut panel costs in half, Barnett says.

Yet another development that has accelerated the growth of solar electricity is government incentives. Many states offer low-cost loans, sales and income tax deductions, grants and rebates to homeowners choosing to take the PV plunge. In New Jersey, homeowners receive a rebate of up to 60 percent of the system cost, and they do not pay sales tax on the purchase. In California, there is a rebate of up to half the cost of the system and a 15 percent income tax deduction on the net cost of the system. In Idaho, there is no rebate, but the state income tax credit for solar electric power is 40 percent of the system's cost. In southeastern Pennsylvania, there is a program that grants up to $8000 toward the cost of a qualifying system.

Who Is Buying PV
The typical PV consumer is someone who is comfortable with new technology and who lives in a state with lots of sun, high electric rates and favorable government incentives. Rick Elmore, a manager for a telecommunications company who lives in Poway, Calif., could be a poster child for the PV industry. Last summer, he signed up for The Home Depot's pilot program to add a 2400-watt AstroPower SunLine PV system to his 1750-sq.-ft. frame and stucco house, which was built in 1975. Elmore says he was an ideal candidate because he pays 13 cents per kilowatt-hour, his home gets lots of sun, and he has just enough area for 24 100-watt modules on his south-facing roof. The installation, which, after rebate and tax deduction, cost about $15,000, supplies nearly all of his electrical needs. His most recent electric bill was only $5.46. What's more, Elmore has fixed his electricity costs. If the price of a kilowatt-hour rises in the coming years, it will barely affect what he pays for electricity.

There are still other reasons to buy a PV system. John Rountree, an architect in Westport, Conn., who specializes in integrating solar PV systems in his designs, says that solar electricity is attractive to people who work from home and who can't afford to be without power for even a day or two. He is a case in point. When there was a power outage in his neighborhood last year, the essential circuits in his home, including his office, the refrigerator and home lighting, continued to be powered by the sun and the battery backup system he installed with his PV system. Rountree also drives an electric car charged in part by the solar energy he produces.

Everett Barber, a solar installer for 27 years with Sunsearch in Guilford, Conn., says another group with good reason to buy PV are those who purchase land that's inexpensive because it's far from powerlines--often just a couple of hundred dollars per acre. Instead of paying the power company the $10 to $30 per foot it costs to string new lines, they can invest in a PV system with enough battery storage to serve their electrical needs--and save tens of thousands of dollars on the cost of their homes.

The Payback
How long it takes to see a return on your money depends largely on the incentives offered in your state and other variables such as system cost, usage, electric rates, climate and the interest rate you obtain to finance the setup.

It also depends upon how you figure your return on the investment. For example, a 2.4-kilowatt system has a net cost of $8500 in a new Shea home. It is projected to save homeowners 50 percent on their electric bills. If the owner can save $40 per month ($480 per year) and has a mortgage rate of 6 or 7 percent, he or she can finance the system with the savings on the electricity bill. So, there is no cash-flow cost to the system and as electric costs rise, the system will begin to save the homeowner money.

A more traditional way to look at payback is by questioning how long it will take to recoup the investment in savings. In Rick Elmore's case, that would be about 10 to 12 years, assuming moderate increases in what his power company charges for electricity--sooner if costs climb faster. After that his electricity will be free for the life of the system, which is estimated to be more than 25 years.

In both of these scenarios, there's another factor to consider: home equity. Installing a PV system, like installing a bathroom or remodeling a kitchen, will increase the resale value of a home. Although it's too early to have statistics on just how much the equity boost will be, it's a good bet that a PV investment will be largely recouped if and when you sell your house. One recent study by home appraisers pegs the value of such a system at 20 times the number of dollars the system saves per year. So, a PV system that generates $480 in savings annually could add $9600 to the price of the house.Is Your House A PV Candidate?
For a PV system to function well, you need at least 200 sq. ft. of south-facing roof area. (Southeast or southwest will do.) It should not be obstructed or shaded by trees, dormers, chimneys or other buildings and can range in slope from flat to 60 degrees. For maximum efficiency, modules should be tilted perpendicular to the path of the sun (latitude plus 15° in winter and latitude minus 15° in summer). Most residential installations, however, sacrifice some efficiency because they are installed at the existing roof slope using fixed brackets--adjustable brackets add expense and can be unsightly.

Climate also determines how well PV systems will work. A 2400-watt setup will produce 290 kilowatt-hours per month in Florida but only 180 in Michigan. Consult a solar resource map to find out how much sunlight you can expect in units of solar energy, called solar kilowatt-hours per square meter per day (kwh/m2/day). It also will tell you what to expect month to month. For example, in Houston, Texas, the average radiation is a whopping 5.7 kwh/m2/day in August. In November it's only 2.4. The National Renewable Energy Laboratory (NREL) has compiled a solar radiation and climate map and data tables for the United States. Its Web address is listed below.

Choosing A System
Buying a PV solar system is a little like buying audio equipment. You can put it together, component by component, and end up with a system that's tailored precisely to your needs, or you can buy a prepackaged system. While a custom system may be able to squeeze every last watt out of your situation, it will cost more and require more technical help when specifying the components. With a packaged system, you don't need to be a solar engineer to ensure that all of the components match up. Packaged systems are available through solar installers, directly from manufacturers, and from the Gaiam Real Goods/Jade Mountain catalog.

Typically, a rooftop residential system that can intertie (be connected) to the power grid consists of between four and 40 modules (watt output varies from 75 to 300 per module, with 100 or 120 being typical), roof mounts and a power panel. The panel safely coordinates your
system with the power grid and includes an inverter that converts the DC power you generate to AC, and other items such as breakers, disconnects, combiner boxes, panels, batteries, and a battery charger if the system has backup capability.When it comes to sizing, don't buy a system that's bigger than what you need. If, at the end of the year, you have produced more energy than you used, it must either be granted to your power company or sold to them at a steeply discounted rate--unless your state allows net metering. Chris Warfel, a solar engineer who has installed dozens of PV systems in Rhode Island, recommends either a 1600- or 2400-watt system for most homeowners.