You may think that solar water heaters are good only in sunny southern climates, such as California or Florida. However, as long as you have realistic expectations, solar can work just fine across the northern United States from the Pacific Northwest to New England. You can find a current list of sources for solar water heaters in the Oikos Product Directory.
That doesn't mean that solar water heaters belong on every roof. The decision to go solar is very specific to the site and the household.
Solar water heaters are really preheaters. They raise the temperature of water before it enters the standard water heating tank. That means the electric element or gas burner consumes less fuel. For consumers, solar water heating has two main benefits. First, it saves money by reducing the amount of energy that must be purchased. Second, direct use of solar heat has a very low impact on the environment.
Heating water is the second largest energy use in typical households, accounting for one-quarter to one-third of total energy costs. On average, an American family of four uses about 64 gallons of hot water per day.
A recent study of solar water heaters in Vermont showed households that use more hot water stand to gain the most. "Our preliminary analysis showed that customers who use more than 4,000 kWh per year for water heating should consider solar," says Nicholas Sinos, project manager with Central Vermont Public Service. At 64 gallons per day, the average american family could use just over 5,000 kWh per year.
"The 10 systems we installed and monitored provided about 50 percent of the energy needed to heat water over a year," says Sinos. In northern climates, a 50 percent savings is typical.
The Vermont study supports research conducted in 1987 by the Oregon Department of Energy (ODOE). They looked at dozens of solar water heaters across the state.
"Our study found that solar water heaters saved between 2200 and 2800 kWh of electricity," says Gary Curtis, analyst with ODOE. "In these systems, solar supplied between 35 and 60 percent of the energy used for water heating."
An installed solar water heating system (collectors, pumps, heat exchangers and plumbing) ranges in cost from $2,000 to $4,000. One way to improve the economics is to find help with the costs. In Oregon, state government thinks enough of solar water heaters that they have offered income tax credits for qualifying systems since 1978. Unlike tax credits of the past, the Oregon program bases the amount of the credit on the energy produced, rather than the cost of the system. The credit goes as high as $1,500. Over 25 states offer some kind of tax incentive for solar devices, including water heaters.
In addition, some electric utilities offer rebates. For example, Pacific Power and Utah Power currently offer $800 rebates for qualified solar water heaters. Rebates also are offered by the Eugene Water & Electric Board and the Sacremento Public Utility District.
Solar water heating isn't right for every situation, so it's best to be an informed and cautious buyer. Here are a few shopping tips.
Before making a major investment in solar hardware, start with some basic energy conservation. Plan to buy a water heater with at least R-16 tank insulation. Insulate all hot water pipes in unheated areas. Install faucets with low-flow aerators and low-flow shower heads. In addition to saving energy on their own, these measures will improve the performance of the solar water heater. You want to hold on to as much of the solar heat as you can.
A careful analysis of the building site is essential. First, determine if you have adequate sun. The collector will need to face within 40 degrees of true south. (True south can be as much as 20 degrees different than where a compass points, depending on your location.) Trees, buildings or other obstructions should cast no shade on the collectors between 9 a.m. and 3 p.m. A handy tool for visualizing how the sun travels across a building site is the Solar Site Selector. You may be able to borrow one from a local energy agency, or you could purchase one for $99 by calling 800-544-6466. (See the April 1991 issue for more about solar site analysis.)
The best angle for the collector is roughly equal to the latitude. Aesthetically it's best to mount the collectors flat on the roof, as long as the roof slope is between 18 and 55 degrees. (A 12-in-12 roof pitch is 45 degrees.)
Here are a few other suggestions before your get started. Contact several solar contractors for information about their systems. Try to get three bids. Talk with others in your community who have solar water heaters. Ask them for advice about equipment and contractors. In most areas, a building permit is required. Check with the city or county building official for details.
Making solar work in northern climates requires careful planning and good information. Contact your local utility or state energy office for more details.
Solar water heating can become a new home feature and a valuable selling point even without installing a complete system. Some builders install plumbing and wiring during construction to make it easier to add other components later.
To make a house solar ready, you need to identify a good spot for the collectors. Then install two 3/4-inch copper pipes with insulation and a pair of 24-volt wires. The pipes and wires run from the water heater to the attic space just below the collector location. If you plan to add a second water tank for the solar loop, you'll need to allow room next to the regular water heater. If space is tight, consider a special tank that allows an internal solar heat exchanger to be added later.
ęCopyright 1995 Iris Communications, Inc.