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Author Topic: Trying to find super cheap way to collect solar  (Read 46084 times)

buzneg

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Trying to find super cheap way to collect solar
« on: October 12, 2008, 07:30:56 AM »
I'm looking for a way to make solar hot water, or CO2, very cheaply. Solar collecting via stallite dish model or trough style need some structure, and have to track the sun. After looking at this link on peswiki http://peswiki.com/index.php/Directory:Charles_Shults%27_Fresnel_Solar_Design and the companies listed on peswiki which use trough solar, often use natural gas or something to further heat the water, because steam or stirling engines are more efficient with a larger temperature difference. By this it seem like it's most economical to use a cheap/simple heat collector to bring the water up to a certain temperature, and then use a high heat concentrator like a lens, or mirror to bring it up the rest of the way. Now maybe a black hose metod is the way to go. Often when I see collectors like this they're under glass, I think this is to insulate the black hose, and cause a greenhouse effect. Just a black hose by itself may lose heat fast from the wind blowing around it, but with a glass cover the air will be held there, and act as an insulator. Right now I'm wondering about 2 black tarps that could melted together every inch or 2 to make the hose, and green house plastic should be pritty cheap to cover it with, with air inbetween ofcourse.

triffid

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Re: Trying to find super cheap way to collect solar
« Reply #1 on: October 15, 2008, 07:24:16 PM »
Go to your public library and check out some books on solar water heater designs(free).Ebay has a lot of good info for sale.Aluminum foil reflects 60%of sunlight.White paper reflects a lot of sunlight too.
All kinds of plastic throwaway bags(like potatoe chips) have reflective mylar in them.A green or dark colored garden hose full of water will pick up a lot of heat.Triffid

TechStuf

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Re: Trying to find super cheap way to collect solar
« Reply #2 on: October 18, 2008, 01:19:15 AM »

Check out this old codger.....his method actually makes good sense:

http://jc-solarhomes.com/MTD/MTD_solar_heating.htm

Also, if it's within your budget and you live in the northern U.S. check ebay for evacuated solar tubes.  sometimes you can get them cheap and they make the best solution for the money when it comes to heating a northern lattitude home hot water supply, without a doubt.

Peace,


TS

pese

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Re: Trying to find super cheap way to collect solar
« Reply #3 on: October 18, 2008, 02:30:14 AM »
I use this:

http://en.wikipedia.org/wiki/Space_blanket


also to isolate my rooms , and some more appications

GP

jeanna

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Re: Trying to find super cheap way to collect solar
« Reply #4 on: October 18, 2008, 05:12:40 AM »
I suppose it all depends on how much sun you get and how cold it is.

The collection box is very successful.

4' x 8' plywood
2" x 4" 's around the edge to make a 4" depth.
paint the inside black
use a black hose
cover the whole thing in plexiglass or glass.

The water will be so hot it will burn you......

until the sun goes off the collector. Then the water temperature gets cold right away.

The price goes up from here. The above was really cheap, but you must use the water when the sun is on the collector.

If you want the water to stay hot, now, you need to devise a way to circulate the water to an insulated tank and get it to keep circulating and then shut off when the sun goes down.

There are lots of ways for the cost to go up.

But if you live in a sunny area and the temperatures stay no lower than freezing in the winter, you ought to be able to do it for cheap money.

--------

I had a friend in Boston who had a thing that size (4' x 8' x 4") that was an air collector which had an inexpensive fan at the top and which circulated the warm air from top of the collector into the room all the sunny days.

Another hole in the bottom leading into the room brought the room air back into the collector to reheat it.

Even in frigid winter days which were well below freezing, if the sun was on the collector the house would be toasty warm when she got home and the heater had been off all day, [when my heater was on all day just to keep the pipes from freezing.]

Solar is great.

enjoy your project.

jeanna

TechStuf

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Re: Trying to find super cheap way to collect solar
« Reply #5 on: October 18, 2008, 06:51:08 PM »

I have had good results with simply making use of SR after it enters one's already insulated home.  Afterall, why reinvent the window if one doesn't have to....

Stand up a piece of sheet metal painted with stove paint inside a window and install a mylar covered plywood panel horizontally outside just beneath the window to increase the amount of reflected SR hitting the sheet metal.  Stand the metal on a couple blocks to facilitate convection and voila.  Also, if one has a storm door, then they have probably experience how hot even a shiny lacquered, light colored wood front door heats up appreciably even on cold days.  Imagine making use of that surface area as well.  Not purdy, but it's easy and practical.

Of course, a better solution would be to install vertical blinds and replace the slats in winter with black chrome slats with short focus fresnel sheets in front of each slat, then install a small tracking motor to the spindle rod blind adjuster so they track the sun across the sky!

Of course, evacuated solar tubes are very efficient and great for use even in the extreme northern U.S.


Peace,


TS




triffid

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Re: Trying to find super cheap way to collect solar
« Reply #6 on: October 21, 2008, 08:33:14 PM »
I have often felt that corrugated cardboard could be used to heat up air with if it was used in a solar hot air heater.Just paint it black and let air flow through the little holes in the cardboard.Triffid

TechStuf

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Re: Trying to find super cheap way to collect solar
« Reply #7 on: October 21, 2008, 08:49:35 PM »

Perhaps the cheapest way to convert solar radiation that I've ever heard!  Given the insulative properties and small corrugated convection pathways, however, it is a comparatively inefficient choice......but it's way better than nothing at all.

TS

jeanna

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Re: Trying to find super cheap way to collect solar
« Reply #8 on: October 21, 2008, 09:15:46 PM »
Actually, as long as it stays dry, cardboard is a really good option.

I used it as insulation once when I was very poor and lived in an uninsulated barn. I stapled it onto the rafters. The heat rising from the heater in the tenant's apartment below mine kept that room toasty. The rest of the rooms with sheetrock walls and ceilings were frigid. (This was Concord, Massachusetts. oo ee baby reallllly cold!) Not that room.

So, keep it dry and go for it.

Also, in an earlier post about the hot air heater (I remember this thread is supposed to be about water!!!) I didn't go into the detail about the greenhouse effect happening inside the unit. This is the reason the unit heats up so well. You know, long rays IR not able to escape etc...

jeanna

TechStuf

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Re: Trying to find super cheap way to collect solar
« Reply #9 on: October 21, 2008, 09:35:57 PM »
Quote
Actually, as long as it stays dry, cardboard is a really good option.


And cheap too!  However, for nominal added cost, try comparing it to black metal, which will radiate heat effectively from both sides.  


If one can afford sheet metal, the decision is a no brainer, really.  


TS

Yucca

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Re: Trying to find super cheap way to collect solar
« Reply #10 on: October 21, 2008, 11:43:57 PM »
I have built a 12kw heating spiral from black irrigation pipe, it is unglazed but to glaze it would be pointless because the plastic and fittings don´t like high temp. This design is best for high flow with modest temp rise, like 10c rise:

(http://rimstar.org/renewnrg/splyucca/splyucca_spiral1.jpg)

Steve Duffrense compiled a page about it on his Rimstar site:

http://rimstar.org/renewnrg/splyucca.htm


I mention how to make a good water heater capable of 60c at the bottom of that page. Just need to get hold of leakfree mat black car or truck radiators from scrapyard and build a glass fronted box over them. I read about this elsewhere online.

Yucca

TechStuf

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Re: Trying to find super cheap way to collect solar
« Reply #11 on: October 22, 2008, 12:06:13 AM »

@Yucca,

I'd be interested to see the efficiency increase in duplicating your setup with high temp stove paint on copper tubing.

Check out the MTD solar heating method link above, it is quite efficient and cheap. 

Or buy a few evacuated solar tubes on Ebay.  They are insanely efficient and reasonably priced!

TS

Yucca

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Re: Trying to find super cheap way to collect solar
« Reply #12 on: October 22, 2008, 03:01:48 AM »
@Yucca,

I'd be interested to see the efficiency increase in duplicating your setup with high temp stove paint on copper tubing.

Check out the MTD solar heating method link above, it is quite efficient and cheap. 

Or buy a few evacuated solar tubes on Ebay.  They are insanely efficient and reasonably priced!

TS
Hi TechStuff,


Yes that would be much more efficient especially if glazed plus you could run mains pressure. Only downside is that copper pipe is quite expensive.

I will check out those links.

Yucca.

TechStuf

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Re: Trying to find super cheap way to collect solar
« Reply #13 on: October 22, 2008, 03:14:26 AM »

Copper just dropped considerably so get it while the gettin's good.


Oops, too late.


lol.

Side note: Some of the most ingenious and cost effective solar setups I've ever seen are contained in the Backwoods Home anthologies.  Great magazine.


TS

triffid

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Re: Trying to find super cheap way to collect solar
« Reply #14 on: October 24, 2008, 06:53:43 PM »
Could Thompston's water seal be used to water proof corrugated cardboard?Make sure it flows through the holes in the cardboard?
The same stuff you waterproof your deck with?Sorry I can't seem to spell it right.I know this thread was for solar heated water but I did point out my tip was for solar heated air.Also black plastic garbage bags could hold some water.i.e. be used in a hotwater system.aluminum paint could be used to reflect light.Triffid