Go Solar for Free Hot Water

Enlarge Image Image Gallery The author's Wisconsin straw bale home incorporates both a solar water-heating system (upper roof) and a photovoltaic solar-electric system. JOHN IVANKO

How would you like to have free hot water for the next 40 years? That should sound pretty good — about 15 percent to 20 percent of a typical household’s energy outlay goes to make sure the “H” tap means what it says. If energy prices increase by 6 percent annually, the average family would save thousands of dollars over the coming decades by installing a solar water-heating system that supplies just 65 percent of their hot water.

I mean “free” literally. Yes, you’ll spend money up front to install the heating system, but your home equity will increase instantly, often enough to offset the cost of installation. You’ll also pay reduced utility bills — saving more money every time rates rise. Within a few years, you’ll recover the initial expense. Experts agree, a solar water heater is far and away the easiest initial investment in renewable energy. Perhaps best of all, you’ll enjoy hot baths or showers with the satisfaction of knowing the energy comes directly from the sun.

A Good Deal, Getting Better

Solar water heaters vary in their details, but they all do the same basic things: gather heat in a solar collector; transfer the heat, directly or indirectly, to the water supply; and store the heated water until it’s used. They use relatively simple, time-tested technology, which is one reason they are a best bet in renewable energy.

It’s important to understand that solar water-heating systems have very low — sometimes zero — operating costs, and maintenance amounts to only about $2 per month. Say you might spend $7,000 to install a solar water heater, when you could install a conventional gas or electric heater for considerably less. But it’s so much less expensive to operate the solar heater that, at some point, you’ll make up the initial difference. When all costs for purchase, installation, maintenance and operation are taken into account, a solar water heater usually equals an electric heater after just eight and a half years, and equals a gas heater in just less than 15 years. From then on, through the expected 40-year life of the solar system, you’ve got free hot water (see “Gas vs. Solar: Compare Costs,” in the Image Gallery).

Consider the positive environmental benefits of a solar water heater, and the deal just gets better. A typical residential solar water heater will offset greenhouse gas emissions by about 1,500 pounds of carbon dioxide (CO2) per year. That’s equal to the amount of CO2 released by an average vehicle every 1,685 miles (based on 19.6 pounds of CO2 per gallon at 22 mpg).