solar power & water

[joshua(Guest)]

I was wondering most of the houses participating in the event laid there solar panels over the solar water heater, does anyone know how efficient this setup is for hot water? There must be a few ways to accomplish this, any one know a good way to?

[Shelley]

You'd think it would be easy.  People have been doing it a long time.  There's several ways to do it depending upon the climate where you are, the amount of sun available, and how much risk you'll accept (possible freezing).

It's a simple goal.  Use the sun to heat water.

There's a pretty good explantion of the various methods on www.aaasolar.com  Go to the "design" section.  Maybe that will help.  If you have an Eureka! moment, come and tell me.  We're struggling with trying to decide right now.

[Amanda_931]

Back in the 70's and early 80's there were some programs to put solar hot water in a lot of houses.  A lot were apparently pretty badly designed or built, therefore soon abandoned, and so there are still, if you are good at scrounging/ferreting them out, a lot of panels not being used, some in garages and sheds, that can be had for little or nothing.

Some friends found some about 80 miles away, spent two days in the rain trying to liberate them (but they were free!).  Once you've got that, the rest is pretty cheap, especially if you are good at playing with pipe, can do a bit of welding.  And that was just last year.

They work pretty nicely.

Weird--a search found two references to that particular unit, plus a cache, but when I tried them, I kept getting "not here, not here, not here"  Don't make no sense.  

Here's Doug's description of his hot water system, about half-way down the page.  Might tell a very handy person enough to do it.

http://www.countrysidemag.com/issues/1_2001.htm#water

This is the kind of system with no water on the roof--suitable for most any climate.

On another list someone was asking if you could piggyback hot water onto power panels--or maybe it was vice versa--the designer said no-no-no--you need all the sunlight you can get for the power, (which he was mainly concerned with) and if you send some off into the water system, your power will behave exactly as though it was so much smaller.

If that was what you were asking.

[Amanda_931]

Here's Doug's diagram of his system.

http://www.daycreek.com/dc/images/doug_kalmer4.gif

And his posting in daycreek's forum on the subject--complete with pictures from 20+ years ago--don't know that I'd recognize him.

http://www.daycreek.com/dc/html/doug_kalmer.htm

[Amanda_931]

Another kind of solar use--fiber optics for daylight in the interior of a building--you can sunbathe as long as you've got sun!  Fiber optics and maybe fresnel lenses.

A bit of discussion here--might be a site worth checking occasionally--I keep running into it:

http://www.treehugger.com/files/2006/01/epoch_making_so.php

And the company home page:

http://www.himawari-net.co.jp/e_page-index01.html

[joshua(Guest)]

Thank you for the info but allready decided on the type of system, I would like the thermosyphen(no power needed!)
Sorry, My question was how well does solar power and solar water mix. One example of this would be University of Missouri-Rolla and Rolla Technical Institute's Solar Decathlons house that was in the mall. There idea of S.T.E.P. (Solar Thermal/ Electric Panel) is intrasting. How practable is it really?
http://solarhouse.umr.edu/house/house_info.html#step

[Amanda_931]

there's been a discussion on another list (the Sunball yahoo group) about using the waste heat from the PV panel to heat water.  The resident engineer was somewhere between dubious and "fuggetaboutit."    It would work best on hot sunny days, very much less well on cooler ones.  

Remember that the solar decathlon projects are sponsored.  This is from the bottom of the site:

The estimate total cost for the project is $208,955, and the projected retail value is $129,580.

there were people who thought that that whole program was designed to prove to people that all solar houses don't work (they can't do better than that in the summertime!!!).

Doug's system uses a small (30 watt IIRC) PV panel to power a small 12v pump.  He believes that that is a perfect use for a PV panel (I'm much more likely to think they are appropriate elsewhere--like being off-grid entirely, but this is a perfect use for panels that small).  And while at least 80% of the time his water is plenty hot, it does run through a--frequently turned off-electric hot water heater.  

Thermo-siphon is almost certainly going to work best for situations where the water won't freeze--where you are direct heating the water, not going through another fluid.  There are some ways around it--John Raabe has one in his house, but....

(times I've mentioned a twenty-year old high thermal mass house that works, a slip formed or cordwood house--it's both--that I know about not far from me, it's Doug's).

There is a really funky Australian system, that puts a small tank on top of a platform, with a solar-hot water panel below and in front of it.  Designed to do not much more than to let someone working outside wash up a little before going in.  I may get around to fishing it out later tonight, it was posted here once before.  You can do better than that.  It still takes a hot water panel.

Are you trying to get flowing water without water pressure?  I am planning it--hot and cold water tanks in the attic, great big hoses coming down, use either a small battery powered or manual pump (e.g., the Guzzler) to get the water up there to start with.

[Amanda_931]

The sunball (link below) guy, Greg Watson, was actually a bit more enthusiastic about combining water with electricity.

http://www.greenandgoldenergy.com.au/

What he said was that using the light directly didn't make sense.

The concentrating system used only for water would be great.

It would probably be easier to do a combination system with air than water--send the circulating air back into your house.

That the big problems would be if the system were designed for electricity and water and the water system failed.  If you had designed it so that the water was the sole heat-removing system, you could fry the PV cells.

Or at least that's the way I understood it.  It's from some posts off the yahoo sunball group.