Make Heat While the Sun Shines

Getting off the grid with solar hot water

by KIM DAVIS

Need something to inspire your sweetie to do the laundry? Consider getting a solar water heater. Vancouver resident Marc Stoiber says that since he installed a system in his home, going down to the basement to do the laundry has become a lot more interesting.

“We installed another tank that is now fired off the sun,” Stoiber says. “On top of the tank there is a meter. When the sun is out, it is up around 80 to 90 degrees, and when there have been a couple of days of rain it drops down to 20 to 30 degrees. It is pretty cool to see it working. It’s a visible manifestation of something that is otherwise invisible.”

But how can solar produce enough hot water in ultra-cloudy Vancouver? Known as much for its overcast, drizzly days as for its beautiful environment, Vancouver actually receives more hours of sunshine per year than most cities in Germany, a global leader in solar installations. While it’s true that solar thermal systems can’t generate as much hot water on an overcast day as a sunny one, according to Joe Thwaites, president of Taylor Munro Energy Systems, in B.C. they can provide around half of an average home’s annual hot water, and nearly all of it in the summer.

Often confused with photovoltaic (PV) systems, arrays of solar cells that convert solar radiation into electricity, solar water heating (or solar thermal) uses the sun’s energy to heat water to useful temperatures. It can be used to warm everything from bathing and swimming pool water to entire homes (think radiant-heat floors). Unlike PV, which comes with a hefty fee (about $16,000 installed), solar thermal is far more financially accessible ($5,000 to $8,000, depending on the size of your household and how much water you use).

Solar heating systems generally consist of solar collectors and a fluid system to move the heat from the collectors to a solar tank, which is installed next to your existing water heater. Collectors, while typically placed on the roof, can also be installed on a wall facing the sun, or can even be free-standing. South-facing collectors work best, but other directions can work, too.

So how does solar hot water work? A simple solar heating system pumps a transfer fluid, such as water or glycol, out to a collector to be heated. Then the heated fluid flows back to the solar tank. Incoming cold water for household use gets preheated as it spirals through a heat exchanger in the tank. The conventional water heater then tops up the temperature as needed. A properly installed and maintained solar thermal system can last for 25 to 40 years. Most components come with a multi-year warranty, and reputable installation companies offer guarantees on their labour. For those handy (or determined) DIY types, there are lots of resources on how to install, and even make, a solar hot water system yourself.

While getting help with the laundry may be reason enough for some to install a solar hot water system, it’s also a boon to your pocketbook. Over its lifetime, solar thermal costs about 3.5 cents per kilowatt hour (kWh). In comparison, BC Hydro raised its rates from 6.7 cents to 7 cents per kWh April 1, and rates will be further increased next year. Natural gas rates are even higher. So when you consider that hot water accounts for 20 to 30 per cent of the energy required by homes, and that energy prices will only continue to rise, solar hot water translates into big savings on your monthly bills.

Solar scores high marks in the environmental category, too. Some analysts estimate that the annual total CO2 produced by the heating of residential water in North America is roughly equal to the emissions produced by all the cars and light trucks zipping around the continent. That means that by installing a solar water heater, you can help eliminate up to two tonnes of CO2 emissions every year.

As an added incentive to encourage homeowners to go solar, B.C. residents qualify for a provincial sales tax exemption. Both Homeworks, a home improvement company, and Vancity offer low-rate loans, and grants are available from Natural Resources Canada’s ecoENERGY Retrofit Program. And according to Dave Wilmot of EnerWorks, a solar thermal provider, a national funding program is on the horizon—and it’ll have a significant B.C. component.

Despite the initial cost, Marc Stoiber feels solar thermal makes perfect financial sense. “It is an investment in the resale value of my house,” he explains.

And, like any home innovation, it’s causing a stir among the neighbours. “It’s a neat and novel thing. People come by [the house] and ask questions and are curious about it. Everyone wants to know that it works, and how it works.”

Kim Davis is a researcher, writer, and designer who appreciated her family’s DIY solar shower during summer camping trips.

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