Keep the heat. Insulating your existing hot water tank will keep heat loss to a minimum. I added fiberglass insulation blankets to both storage tanks.
Consider your source. The warmer your source of domestic cold water, the hotter your output from a solar hot water system. Our home is fed by a 98-foot well with 50°F water. Originally, our well’s pressure tank had no insulation. As a result, the cold-water temperatures would drop significantly in winter. When replacing our leaking pressure tank, I wrapped the new tank with 6-inch-thick fiberglass insulation, added several inches of solid foam-board insulation on top, and enclosed the tank in a draft-free wooden box. Now, in the winter, I get 45ºF water feeding the house and the solar storage tank, and no longer have to heat the pressure tank with a 120-volt heat lamp to keep it from freezing.
As is true of most RE systems, the financial rewards for solar-powered hot water trickle in slowly over the system’s lifetime—which can range from 20 to 30 years. All said and done, this project, including shed construction and mechanical installation, took three months of spare evening and weekend hours, and cost almost $7,000.
Since the system only came online in September 2007, it’s too early to accurately predict our monthly savings, but I can say that it has required little backup so far. By staying attuned to the weather and running the big laundry loads on sunny days, we minimize the number of kilowatt-hours we consume from the grid to heat our water.
Compared to our monthly electric bills for the past six years, the first three months of operation with the new system show that our average usage has dropped by 547 KWH per month. At our current rates ($0.07 per KWH), that reduction amounts to a savings of $38.29 per month.
After accounting for the $2,000 federal income tax credit and lower monthly bills, I suspect that we’ll likely have recouped the expense of installing the solar hot water system in eleven years—although it could be longer, depending on future repairs. That payback time is more than reasonable when you take into account that electricity rates have gone up 19% in the last two years and will continue to climb, and considering that I liberally sized my SHW system. Plus, the new system nixed my plan to spend at least $1,000 on a new front-loading clothes washer, which would have used less hot water.
But the ultimate reward is a good sun-heated bath for my aching joints after a long day of work—and knowing that we are doing our small part to reduce demand on non-renewable resources.
Bob Inouye lives with his wife Carol in the foothills of the Cascade Mountains in Washington. The couple happily shares 180 forested acres with horses, mule deer, elk, turkeys, beaver, salmon, and steelhead. Solar hot air collectors are next on their RE drawing board.
Aero • www.aeroflexusa.com • Pipe insulation
Alternate Energy Technologies • www.aetsolar.com • Collectors, circulator pump
The Alternate Energy Store • www.altenergystore.com • SHW storage tank, thermometers, propylene glycol
Uni-Solar • www.uni-solar.com • PV module
Solar Water Heating, A Comprehensive Guide to Solar Water and Space Heating Systems, by Bob Ramlow with Benjamin Nusz • www.arthaonline.com/bookpage.html