Where are the different solar heating systems comparisons?

Discussion in 'Survival & Sustenance Living Forum' started by Vincine, Sep 4, 2012.

  1. Vincine

    Vincine New Member

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    I can’t find documentation or models online that compare different solar heating systems, all things being equal, to each other. I can only find 'Before & After' comparisons, 'With & Without', or 'Solar vs. Conventional'.

    For a solar hot water house heating system: Is there a conventional wisdom as to whether; a well insulated above ground heat storage tank, is more or less effective, than a buried below the frost line geothermal tank that would ‘preheat’ the water to about 55F? Presume same size house, collectors, degree days, sunlight, etc.
     
    Last edited: Sep 4, 2012
  2. mountainman13

    mountainman13 New Member

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    Not a clue but I would assume geothermal is the better option.
     

  3. c3shooter

    c3shooter Administrator Staff Member

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    In-ground heat storage tanks are usually insulated like crazy so you do not LOSE heat to the surrounding soil. Their purpose is to hold water that is heated by the collectors,so that the heat can be doled out at night or cloudy days. They are more efficient in that the surrounding soil is usually warmer than the air in winter, but you do not want your nice 190 degree water bleeding heat out to the soil.

    In ground tanks can be VERY large, VERY well insulated, and do not have same strength/ support issues that a comparable sized above ground would have.

    Would love to sit down and run the math on putting up a half dozen electric wind turbines, and feeding their output directly to electrical heating elements in a VERY large insulated tank of water- say, 15,000 gallons.

    Let it run all summer, you have about 15 million BTUs stored there.....
     
  4. Vincine

    Vincine New Member

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    Okay, I think I’m missing something. The in ground storage I’m thinking about isn’t supposed to be insulated from the ground. It’s supposed to be a massive store of water or stones at the same 55 degrees the earth is below the frost line all year round. It is used to ‘preheat’ the water or air to 55 degrees before being brought the rest of the way up to heat the house, or to cool the house in the summer.

    Good point.
    Me too! I also would love you to sit down & do the math. ;)

    Really? Two transfers of energy, from wind to electricity and then electricity to water, instead of just one, sunlight directly to water? That’s twice the loss, but then I guess you don’t have to pump the water to gain all the heat. Of course there is nothing saying you can’t have both at the same time. It is often windy in bad weather when it is cloudy, day or night; and bright and sunny when it’s calm, and ocassionally bright & windy at the same time.

    Nice. Saranac Lake gets the coldest spot in the nation award every few days over the winter. (It’s never specified if it’s just the lower 48, or includes Alaska too, or at least where they have weather stations in Alaska.)

    Anyway, I can’t find any models that compare the various strategies to each other. I would have thought this would’ve been online by now. Maybe even an application with variables one could plug in; house volume, sunny/cloudy, ambient temperatures, insulation rating, etc.

    (This is just academic. It seems have just enough $$ to buy some decent land, OR build a structure. Not both, and besides, I don't have the stamina anymore. Nuts! Thanks for your interest.)
     
    Last edited: Sep 5, 2012
  5. willshoum

    willshoum New Member

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    Heating unit on two feet....

    My wife, when ever she's around the temps flare.......:eek: Water boils with out the stove being on when she stands over the pot.....lol.....And my daughter is like the next thing to come a long to replace oil.....Me I'm the old candle thats been burning at both ends......Ahhhh, solar power, been around for billions of years........And man won't get the hint till the earl runs out......:mad:
     
  6. c3shooter

    c3shooter Administrator Staff Member

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    Ummm- THAT is not a storage system, but is a geothermal system. Looked at using a water-freon-air heat pump some time back.

    You can pull heat out of 54 degree water easier than you can out of 10 degree air. Geothermal heat pump pulls water from a well, strips heat, returns water to another distant well.

    As far as "Coldest place in the nation today"- yeah, they usually ignore Alaska. Have been out in the field at -65 air temps. However, Alaska is a BIG place- not all of it is THAT cold. I left Juneau one evening (34 degrees) and flew into Chicago (-15 degrees)

    For that matter, there is one spot here in VA where it once got to -34. Place called Mountain Lake (where they filmed Dirty Dancing).
     
  7. Vikingdad

    Vikingdad New Member

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    I am intrigued by geothermal, the way that C3 describes it. Two wells, one to pump out of and circulate the water through the floor and walls to cool/ warm the house and the other to dump the water back into the aquifer (distant from the first draft well).

    I am also very interested in a hot water heater and would like to install a Solahart water heater. http://www.solahart.com.au/solar-water-heating.aspx

    I already have a 12.5 kW solar PV grid-tied rooftop system on my house. I'm hoping to supplement that with more in the future.
     
  8. TLuker

    TLuker Active Member

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    The geothermal system you're referring to works ok. A heating and cooling guy use to install them around here years ago. You can run a certain length of pipe in the ground at whatever depth below the frost line (if you have a frost line). A low volt pump then circulates the water in the closed system. The ground keeps the water at a constant 55 degrees. That same guy would also run pipes on the bottom of a local lake, which also stays at 55 deg., and get the same effect but with less pipe and very little digging. It was a very efficient system but you needed a supplemental heat source to go with it unless you're comfortable with low 50's in the house. :)
     
  9. scottmac

    scottmac New Member

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    My old manager and friend built a cordwood home in MN, and created an online journal called daycreek.com . Over the years Alan has done a lot of research, and he's pretty good at describing WHY he chose to do it the way he did versus the other options.

    Give his site a look. www.daycreek.com - look for the DayCreek Journal" link at the top yellow box.

    His current setup is a 16-sided, two story cordwood home. It has three-layer walls; 8" cordwood, 8" foam, and another 8" of cordwood (24" depth total). He started with only solar heat and hot water, later adder solar PV power.

    It's a very cool place. The Journal is a pretty good read and has a lot of great info for self-sustenance and living off-the-grid.