Heat Your Home With Solar Hot Water

Tap into free solar energy with a combined system to heat your home and your domestic hot water.

| February/March 2011

cabin solar thermal

This Wisconsin home has 320 square feet of solar collectors that provide home heat and domestic hot water.


When Terry McIlveen built his home in Maine in 1997, he made the unusual choice to install radiant floor heating. “People thought I was nuts,” he says. However, since that time, radiant floor heat has become increasingly popular, and it’s easy to understand why. This type of heating system works by pumping hot water — or water and propylene glycol (antifreeze) — through a system of tubing in the floor. That means houses using this heating system get warmer from the floor up. In the winter, there are no cold floors underfoot — instead the floor is the warmest part of the home.

McIlveen soon discovered an additional benefit — radiant floor heat is a great match with solar hot water. If you already heat your home with hot water, it’s just one more step to heat that water with solar energy. In the spring of 2010, McIlveen hired ReVision Energy, a southern Maine solar company, to install rooftop solar collectors to help heat his home and produce his domestic hot water, thereby cutting his fuel oil consumption by up to 25 percent each year.

The system cost $20,000, so McIlveen chose to finance it through a loan. His exact savings on fuel each year will depend on how much he has to run the heater in the winter, as well as the ever-changing price of fuel oil — but he knows that if he saves just two fuel tanks a year, he can cover his loan payments.

Using solar hot water for space heating won’t supply 100 percent of your heating needs. You’ll still need a supplemental heat source, so you won’t be able to scrap your furnace or boiler. But in new construction, that supplemental heat source can be much less expensive (a smaller system, for example). However, under the right conditions, a solar thermal system can replace a significant portion of conventional energy sources for both space heating and domestic hot water.

Tim Merrigan, senior program manager for solar heating and cooling at the National Renewable Energy Laboratory, says a solar thermal system can carry up to 40 percent of the annual heating load for some homeowners. Bob Ramlow, who is a solar consultant with extensive experience in solar heating systems, says that most people in well-insulated, tightly constructed homes can save up to 50 percent.

Using more solar energy and fewer fossil fuels has many environmental benefits. By investing in such a system, you’re reducing greenhouse gas emissions and other forms of pollution that come from mining and burning fossil fuels. But there are often cost savings, too, because you’re heating that water with free sunshine, and any savings on your fuel bills will add up. That’s why Ramlow emphasizes that if you’re pricing a system, to look not just at the initial price tag, but at the return on investment over time. The return will vary depending on a number of factors, including the price of heating fuel, your home’s solar exposure, and its average heating loads. Ramlow estimates that for the solar heating systems he has installed in Wisconsin, a typical return on investment is between 10 and 15 percent a year.

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11/25/2013 1:41:47 AM

Excellent idea. I did not know you could run hot water underneath your floors. Also, one idea for those with pools... if you get an electric heat pump to heat your pool water and solar energy for your home... you can have warm water 24/7/365 thanks to the power of the sun. :) - Eddie http://www.sacramentosolarcompany.com

5/28/2013 11:15:22 AM

Solar heating is a great option for homes in all conditions. Sometimes its not practical for residence that dont get much sunlight, but anywhere around the earth, people should take advantage. Consider how much poor families can benefit if there were solar in urban location in south america, and mexico. As a member of the solar community in the los angeles area, novel remodeling strives to bring solar energy to families in need of saving money. Consider the savings and choose solar today. 


t brandt
2/1/2011 6:04:37 AM

This article points out the dilemma we have: fossil fuel is quickly running out and alternatives ARE NOT CHEAP. $20,000 [make that $30-40,000 with finance charges] to supply only 1/4th of your heating [and no cooling]. Conventional fuel will provide both for less than $2000 per year. This system would have to last about 50 yrs to break even- just about the time when it would have to be replaced. And most areas of the US just don't get enough sunlight to make this system effective on a reliable basis.

1/21/2011 2:56:46 PM

Radiant heat is the most comfortable and efficient form of home heating. SHEM offers a number of solar thermal systems designed to seamlessly mesh with radiant systems. Solar pre-heated water reduces fuel costs and increases system life! Check out www.simpledrainback.com

joergen andersen
1/21/2011 10:52:31 AM

Sun heating is good but not best, think ground heating together with a little windpower to run the system, then you have your heating nearly free, only the invenstment to pay. Run this system for 2 years now and heeating and electic bills is less than 300 a year, yes you read right below 300. Must say you need to have a house with good windows and doors(european style) and the house must be vell build and 3 glass window and ins. well. Takes time, but you SAVE in the long run and the inv. is getting better and so are you.

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