The next time you settle beneath the suds of a warm bath, linger under the relaxing spray of a hot shower, flip on the dishwasher or set your washing machine in motion, consider that up to 20 percent of your annual energy bill is generated by heating water. Consider also that if you had a few solar collectors on your roof you’d be getting most of that hot water for nothing.
Though the cost of residential solar space heating and air conditioning still remains prohibitive in most cases for this part of the country, using the sun to heat water is a practical and relatively inexpensive application of solar energy that’s been in use in the South since the early 1900’s.
Unlike solar space-heating systems, which involve a lot of hardware, the technology for domestic hot water heating is fairly straightforward. Many firms make kits that can be installed by a homeowner who has a good understanding of plumbing. Starting at about $1,300 for a family of four, these kits generally consist of two or three solar collectors, a storage tank, a small pump and thermostat.
They work like this: Water is circulated through the system by the pump and is heated as it passes through the collectors on the roof. The thermostat cuts off the pump whenever the temperature in the collector becomes lower than that of water in the tank. In cloudy weather. water in the tank will stay warm two or three days. During freezing weather, the system is protected by warm water circulating through the pipes or by draining the pipes. Others use an antifreeze liquid, but they are more costly and are generally thought to be impractical for this area.
To dispel one common misconception at the outset, the sun will not provide 100 percent of your energy needs for heating water. That would require more collector and storage space than would pay off in a reasonable length of time. Most manufacturers offer systems that will meet up to 80 percent of your needs.
So what kind of savings does this mean to you? Based on Dallas Power & Light Co. and Federal Energy Administration data, the average family of four in Dallas spends about $ 170 a year to heat its water electrically. With a system that handles 80 percent of it’s needs, this “typical” family (this is really a very general figure, since water-use habits vary) could be putting aside roughly $140 a year with solar heat. If this family were among DP&L’s top 10 percent consumers, the savings would be more like $200 annually. If you’ve got a gas heater, however, solar assistance probably wouldn’t be practical for you – unless you’re heating a pool, in which case the savings would be considerable (see D Magazine, April 1977).
The payback time on a solar heater in this area will generally be eight to ten years, based on the current average rate of 3.2 cents per kilowatt hour. That may sound like a long time, but remember that energy rates are going to climb, so you can count on the payback time being shorter than estimated at today’s prices. Also, even if it takes your investment 10 years to pay for itself, you’ll be getting most of your hot water free for the following decade, because a good system will last 20 years.
As far as long-term savings go, a person who saved $ 140 in 1977 using a solar water heater would be saving $380 by 1992, applying inflation rates used by the FEA. The total savings by that time would amount to around $3,700.
So in a sense, when you install a solar system it’s like buying your own utility company – eventually it pays for itself and begins returning regular dividends. Besides saving money, you’re doing your bit to conserve energy and reduce pollution. Using a conventional system, however, is like renting. After 15 years you’ve got nothing to show for it except higher bills.
Keep in mind, tot), that the House Ways and Means Committee recently approved a tax credit of up to $3,150 for those who use the sun or wind as an energy source. Though it will take a final vote by Congress to put it into effect, the credit would mean that fora system costing $1,500 installed, you’d actually be paying $ 1,000. That could bring your payback time to about seven years maximum.
The primary thing you’ll want to be concerned with when you start shopping for a solar heating system is the collector, since storage tanks and pumps are fairly standard items. An important consideration is collector efficiency – how much of the energy hitting it is put to use? This is measured in British thermal units (B.T.U.’s): the quantity of heat required to raise one pound of water one degree Fahrenheit. Efficiency must be balanced against cost, however.
For example, say you have two collector panels, each receiving 200 B.T.U.’s per square foot per hour. The first costs $ 10 per square foot, has a 60 percent efficiency rating and delivers 120 B.T.U.’s per square foot. The second costs $6 per square foot, has a 50 percent efficiency rating and puts out 100 B.T.U.’sper square foot. Although less efficient, the latter would be the best buy, because it delivers 16 B.T.U.’s per dollar, while the first generates only 12 B.T.U.’s at the same price.
If you’re not familiar with the brand you’re looking at (there are about 300 different collectors on the market today), ask to see studies done by a university or independent testing group to verify claims made about the performance of a panel by a dealer. Don’t take anybody’s word for anything, particularly if a dealer has designed his own system but has never installed one. If the dealer refuses to give references, suddenly gets amnesia, or just can’t seem to locate the names and ad- ! dresses of the folks he’s dealt with, consider him suspect. Remember that when you ’ set out to select a solar system you’ll be one of the brave pioneers doing business with a brand new industry, which is bound to attract some shifty or inept characters.
As far as figuring out how big a system you’ll need, most manufacturers base their recommendations on the national average – 20 gallons of hot water a day per person. Storage tanks come in 60, 80 and 120-gallon sizes. (They’re installed next to your water heater which is used as a . backup.) Thus, a family of four would i require an 80-gallon tank.,The number of | collectors will depend on the efficiency of the model you choose, the number of gallons being heated and the degree to which you will rely on the sun to do the heating. Usually three collectors will take . care of about 80 percent of the energy needs of a family of four. Complete systems of this size range between $ 1,500 and $2,500 installed. It takes less than a day to put one in.
Though you’re venturing into unchar- ted waters when you shop for solar heaters, efforts are being made to see that you don’t fall victim to a hustle. Acutely aware of the possibilities for abuse, a handful of air conditioning and refrigeration contractors interested in solar energy have formed the Solar Sub Group of the Air Conditioning and Refrigeration Contractors Association of Dallas. The goal of the group is to help the city establish building standards and foster an ethical atmosphere in which to conduct their business.
“The last thing we want to see,” says Roger Gibson, chairman of the group, “is a bunch of blue suede types getting into solar here.”
The solar energy business is already experiencing some of the same growing pains that the swimming pool industry went through a decade ago, and your best defense against getting ripped off is to educate yourself. For good basic background, try the booklet Buying Solar, published by the Federal Energy Administration. You can get one from the U.S. Government Printing Office, Washington, D.C., 20402. stock number 041 -018-00120-4 ($1.85). Another good source to help you sort through the scores of collectors on the market today is the Solar Industry Index, published by the Solar Energy Industries Association, 1001 Connecticut Ave. NW, Washington. D.C., 20036 ($8 prepaid). It includes basic information and costs.
The serious student should write the National Solar Heating and Cooling Information Center, P.O. Box 1607, Rockville, MD, 20850, for the Reading List for Solar Energy, which includes some 50 books and magazines. Researchers there are also manning phones to answer general questions, do literature searches and serve as a referral point for individuals interested in solar. The toll-free number is (800) 523-2929.
Because solar energy is such a young industry in Dallas, no companies have had a chance to make a name for themselves. But a good place to start is Suburban Heating & Air Conditioning Co. Suburban has a wide range of systems and equipment to offer, and is one of the few firms in town that employs a solar engineer, Shing Leung, who has access to a computer for the most accurate determination of individual solar needs. Leung set up the solar laboratory for undergraduates at Southern Methodist University and participated in the development of Dallas Power & Light Co.’s 1976 Solar House.
Another firm with broad capabilities and access to computer assistance is United Plumbing Co. United installed the solar collectors on the La Quinta Motor Inn in Dallas, which is the only lodging facility in the country that uses solar energy for space heating.
Also worth investigating is Solar Enterprises in Arlington. The firm specializes in domestic water heating systems and has opened a new plant where it produces panels of its own design. You can buy kits directly from the plant. Distributors include Solar Mechanical Inc. in Arlington. Dennis Plumbing in Grand Prairie and Suntech Solar Systems in Dallas.