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Solar Water Heaters

If you live in the northern U.S., you will probably benefit more from solar water heating than you would from solar power (photovoltaic or PV).  Because of the amount of average cloud cover and other atmospheric issues in the north, PV is not as effective as it is in the south – the energy production difference can be as much as 30%.  Solar water heating, however, does not require direct, full sunlight to operate and can still provide a significant amount of energy for a home.

Solar-heated water can be used for showering, dish washing, etc., as well as for radiant heating in the home.  In a grid-free home, it can be the primary means of heating as well as a constant, renewable source of hot water for all types of uses.

Solar water heating systems are also easier and cheaper to install, can last the lifetime of the home, and can provide hot water for nearly every day of the year in most climates.

The system you choose will depend on your budget, needs, and expected uses.  There are two basic types of systems: active and passive, using either direct or convection heating.  Active systems are pumped and circulated using external power (often from a small solar panel or other electrical source), and passive systems are moved by natural convection (the expansion and contraction of liquid with heat).

Active systems are more common and are generally capable of higher capacities than are passive systems, but the active system will require more maintenance and an electrical source.  Passive systems are usually not as large-capacity and are not nearly as high-performance, but are generally more maintenance-free than active systems.

Whichever is used, the heating method is either direct or convection.  Direct heating is not as common in the far north, since it involves moving the water through the eating elements themselves, which can lead to freezing in cold temperatures.  Convection heating is more common as more heat-conductive liquids with anti-freeze properties can be used.  These collect heat in the panels and travel through a water tank or coiled water pipe to convey the heat to the water, circulating back up to be re-heated in the panels again.  Convection heating allows a closed-circuit of liquid, preventing many of the plumbing and maintenance problems that are more common with direct heating systems.

In most climates, solar water heating systems can provide up to 85% of a household’s hot water needs annually.

Many solar heating systems circulate water or fluid during the day and, when sunlight fades and temperatures drop below a specific level, they “flush,” removing all of the liquid from the panels to pump it back in when valves open with a warm day.  This preserves heat, keeps the system from cooling rather than heating water, and acts as a safeguard against freezing.

For the off-grid home or cabin, solar water heating can provide most of the household’s hot water needs as well as hot water for radiant heating to supplement other heating in the home.  Some solar heaters are made specifically to heat (or even cool) a home and can be combined with a water circulation system to provide basic ambient heat.  Coupled with other heat sources such as a wood stove or gas heater, these systems can keep a home quite comfortable even in the harshest of winters.

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  1. Absolutely love the solar hot water heaters and would like to be kept in the loop about their development and when they become affordable. Cordially, JJ

  2. You can easily make your own solar hot water heaters with used hot water tanks that are usually thrown away.
    Three of these tanks in a large black painted box with a glass covering will generate a lot of hot water. You will need to hook it up with a blending valve to intersperse with cold water because the sun heated water gets too hot for showers or bath.
    You can buy the HOW TO DIY plans from Mother Earth News of years past, get their past issues on DVD from when they started. Not the yuppie stuff they print now.

    • Making my own solar hot water heater is interesting using used hot water tanks, but weren’t the tanks discarded because they were bad or worn out? Wouldn’t their life span be zero to very short? Just trying to understand how this would be a good way to go. Thanks.

      • Believe it or not, most people buy a new water heater because the thermostat went bad. So the whole thing gets replaced, instead of the thermostat. So, I would have to say no, their life expectancy is not short. You would have to examine them carefully; if there is rust showing through, don’t use.

  3. I was just in Hawaii a 2 months ago (working there for 6 weeks – so sorry I had to miss the winter) and they have a state law MANDATING the installation of solar water heaters for all new construction. It hs been in effect for a few years. The newpaper article where I read about it, was effectively whining that exemptions were made for something like 23% of new construction and wants these ‘loop holes’ removed. Those exemptions were for other alternative approaches to using electricity as a source.

    I really love the idea, but only based on my own wishes, rather thatn that of the state. They indicated the cost after state, federal and electric company rebates was only around $2800.00. Still a bit much, I’d say. So I have a hard time justifying such an expense.

  4. Charlotte Boucher

    I have a well that is 240 feet deep and I am interested in a solar that would pump water in case of a outage, what kind should I purchase?

    • There is a company we used universal energy in kansas they gave us several viable options. Solar pumping , generator backup pumping or a hand pump that draws from 300 ft [email protected]

    • I work for a well driller in Indiana, one of the first things you should know before purchasing an expensive pump, should be your static water level, how deep is your current pump hanging, and what is the drawdown (how much does the level of water in the well go down after a time of continous pumping and at how many gpm) this information should be available on your well log. Indiana and Michigan well logs are sent to the state and posted and searchable online, check with your state dnr to see if this is available in your state.

  5. Good how-to videos to be found on YouTube. Also a beer/soda can air heating system is on there too. Plan on making that one before next winter.

  6. This is a bonafied e-mail address in a small valley in Wyoming. Our phone provider is privetly owned and is also our computer provider. Its refered too as a monopoly by the people that move here and can’t get anything else, when they are use to big names like AOL ect. that we can’t get here. We are on well water this is mostly farm area that raise cows. My question is, since there is talk that they want to rig up water meters, is there a way that we can use a way to bring up our water without using the electric pump and switch to a manual pump like hand pumping like in the old movies. It would be a life saver during lack of electricity. Thanks for your help.
    joan bardier in Silverstar monopoly area.

  7. When recently visiting Israel, we noticed right away the numerous water tanks and solar panels next to them on mostly apartment buildings. We were told that these were all solar heated hot water tanks. So they must have this working very effectively.

  8. Regarding solar for pumping water, what you’re looking for is a photovoltaic system
    that generates electricity from sunlight. You can either drive a pump directly with the electricity,
    so you’ll only get flowing water when the sun shines, or use the electricity to charge a bank
    of batteries that you can then draw upon to run the well pump. If you can put a storage tank
    above the level of your home, either on a hill or a tower, then you can have water pressure
    caused by the elevation difference between the stored water tank and your home.
    You can start reading and learning online about photovoltaics, or buy some books so when
    you’re shopping for a system you’ll know a bit about what to specify when sizing the system.

    I used to install active solar water heating systems here in Colorado back in the early to mid
    ’80s. Our systems used a silicone based heat transfer fluid and I can vividly recall burning my
    hand on the hot return pipe from the collectors. The storage tanks were 84 gallon tanks for
    domestic hot water only, up to multiple 120 gallon tanks for DHW and space heating systems.
    We did a lot of business until the solar tax credit went away under the Reagan administration.
    The credit was designed to get the industry going until it could stand on its own against the
    rapidly rising natural gas prices. Instead, the gas prices collapsed and solar couldn’t compete
    against cheap nat gas.

  9. I need advice on all types of utilities: water, sewer/septic, electric and gas. Currently, I am in the process of finding land at least 150 miles from a large city (in Texas). The last time I lived in the country the house had water, a septic system on the land , propane trucked in and only 1 electric co-op. I’m searching for land even further out and would like to be less dependent on utility companies. The problem is most options are expensive to have installed (solar, a well being dug, cost to run the well pump, septic systems that have “sprinkler systems” and have to be inspected/maintained every 3 months by a company) I look at my highest expenses (where I live) and other than gas in my old truck, it’s the utilities. I would appreciate any advice you can give me on other options. I do not need much, just looking for peace in my life, and want to live off the land to the best of my ability. Thank you for any advice you can give me.

  10. I heard the Reagan administration did away with the Solar tax credit due to widespread abuse. My brother used to provide solar installations in the 80s, and it affected him. I was disappointed.

  11. You can find DC pumps here:

    Solar Tax Credits are back. Stop worrying about the 80’s, they’re over. The federal government has a 30% tax credit on solar thermal. Depending on which state you live in you can usually get 30% or more from them. I install solar hot water in Georgia. Follow the link to learn more about current incentives to reduce your dependence on utilities!

  12. Has anyone ever tried using windshield washer fluid as an antifreeze? up here it is a fraction of the cost of antifreeze, but does it transfer heat well? (winter washer fluid is typically good to -40 or -50)

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