New Solar Thermal Panel Project
I just added a new solar thermal panel project to the project section of the main site. It works a lot better than the first one did. Check it out and leave a comment here.
- Posted in : Pictures, Sietch News, The Naib
- Author :The Naib
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You could probably fit in a few old refrigerator coils and increase the flow. And how about a piece of blue styrofoam for the back so that it will work well in winter? Also for the glass, a theropane window may work best (two layers of glass with a vacuum space). These are expensive, but I have seen them thrown out.
Why put a reflector on the back?
In Israel we have many sun-heated hot water tanks. The idea is that the large area of black surface absorbs the sunlight radiation, heating up, and transfers the heat to the pipes via conduction (either directly, or using the air inside).
The glass prevents heat from escaping by conduction, but permits heat to enter (and leave) by radiation.
By making the back aluminium foil, you are refleccting much of the heat back outside before it’s absorbed into the pipes.
I should note that for that to work you need the back to be conductive, and the rubber is probably not a good idea.
Insulation would for sure increase flow in the winter. We ended up insulating the bucket the water flowed into, but insulation on the panel would also help. We will incorporate these suggestions into the next one.
We only found the one pain of glass, but i would have killed to find a nice insulated window frame at the dump, that would have been a real find.
yea that was the problem we had, the rubber backing was just sucking up all the heat, the backing got very hot but the pipes didn’t. With the foil in place, we found a significant increase in the amount of heat the pipes picked up. If the backing was metal and the pipes were attached it with metal brackets it might work well.
If you build one without a reflector inside let me know what your mileage was as we were debating foil vs no foil.
Thanks for all the comments, keep them coming.
I really enjoyed the article on the 2nd solar panel. It was so well written and the visuals and instructions make me confident that I can do it. That being said, as a New Yorker, I don’t understand the need for this. Is it for camping? Why would you need hot water like this & why wouldn’t you just leave the a bucket of water in the sun & wait for it to heat up on a hot sunny day. Any insights?
Thank you for your interest in the solar panel project, let me answer your questions as you asked them.
The project was done as a way for people to have a project they can do at home that will demonstrate the principles involved in solar thermal technology. The idea was to show people that the technology works so well that even a little home brew project works well. If you wanted to do solar thermal panels for your home you would buy one of the many commercially available packages.
This project could be used for camping to heat up a batch of water for a warm shower while in the woods.
As far as waiting for a bucket of water to heat up in the sun, if its a cool day say 50 out, your bucket is never going to get hotter than 50. If you have a panel like this you can create 100+ water on a 50 degree day. This would make for a much nicer bath.
The panel is sort of a “proof of concept” project, but it does have useful applications. It also is a fun project to use to teach science principles of solar energy to students. Its more of a learning project, and a way to educate people that these sort of technologies are available.
I hope this helps.
Thanks for getting back to me. This definitely helps
me understand the intention of the project better.
Tara -
The real point is that if you want hot water in your house, you (or your landlord) have to spend energy to heat it up. The energy you have to use is proportional to the temperature difference between the water in the pipes from the utility and the hot water you want (ie, if the water coming in is cold, you have to spend more energy to heat it up.)
So, if you can harness the power of the sun to pre-heat the water before it gets to the hot water heater, you can have hot water in your house, but spend a lot less energy to do it. People sell pre-heating panels to put on your roof and do this for you, but this project has managed to make a pre-heater for 5 bucks.
Heating water accounts for a significant percentage of home energy use, and if we all installed one of these, home energy use would be cut dramatically.
I bet it would thermo-siphon if you flipped the whole panel over so the lines came out the top. Of course, hot air in the chamber would escape through the slit for the pipes, which would reduce efficiency, although you could pack the holes with something (spray foam, caulk, or just tinfoil; the point is to stop the flow of air). If you make those holes airtight you would have to let the air expand some other way, though, and probably a vent hole on the bottom would be best, unless the whole thing isn’t airtight, in which it won’t matter.
Also, you don’t have to siphon the water through to prime it. Just fill it with a funnel.
I like the idea, and it’s simplicity. I can see many areas to use this. But what about the left over refrigerant in the tubing, are you safe to wash/drink with this water? Can something be done to clean the tubing thoroughly if it’s not already?
What about using an old car radiator? You would have to clean it very well, but it is already black metal and has more metal fins to transfer the heat to the water. It also seem more readily available.
I thought of creating two of these and linking them together or making my own with copper pipes. The real trick for me Iis that I want to use it for my pool How does anyone suggest I hook-it up so that the pump can feed the panels and then it will be forced back through into the pool.
If i get two linked together then the waterflow speed will be counteracted by the length and flow capacity of the system. Plus i think 110 is a little warm for my pool, g-d forbid i let it stand and get to 170 EEEEEKKK
@Lee:
Generally the water in a system like this is not directly used. The tubes of a pre-heating system like this are generally run through another water storage as a heat exchanger system.
This is about the best picture I could find in a few seconds:
http://www.malignani.ud.it/WebEnis/NorthWind-SouthSun/power/images/water_heater.jpg
Hopefully this answers your question :)
Its great to see you experimenting, but you really should do some research how the best solar panels work.
Think about it…. first, roughly 1m sq is about 1kw of energy.
So you need to get as much of that energy as you can.
The 1st type of solar panel is the flat plate collector and is
the cheapest to construct…. note it is called the flat plate.This is because you want the biggest surface area. you can runyour pipes over the flat plate, they must be connected to the plate.
So first you want your
1.wooden frame
2.Insulation - to stop heat escaping from the back
3.foil, this reflects back heat (note its not reflecting light as it is hidden!!)
4.collector plate - sheet of copper or alu or even steel if you have to.
5.tubes, these need to have a good connection to the plate -plumbing solder?
could be behind the plate, but nice to see them.
6.Paint, matt black high temprature (like engine paint) there are other options also. this paint goes onto the metal plate and pipes
7.Glass - possibly double glazed
The other type of common solar pannel is the evacuated tube, which work pretty well even in cold weather - but they have to be specially constructed - you can buy the tubes on there own of course..
Very interesting project, over here in the UK there alot going with the cost of energy (oil, gas, electic) shooting up that people are thinking of cheaper greener energy creation method.
Recently there was a programme on tv in the uk called ‘It’s Not Easy Being Green” where a family attempted (pretty well) to be as self relieant as possible. Is this series they manages to :-
Build a water wheel that generated electricity to power their lighting,
Installed a small wind turbine to run a water pump to take water from a spring into there house for the toilet,bath,shower,wash (saving on water bills),
Installed a larger wind turbine to reduce electic bill more
Installed a solar thermal system - give heated water 6mths per yr, (they did a tester using a old raditor they painted black but had limited success),
Had a system that kept a greenhouse hot all day and night - like this one so simple a cost nothing to run.
http://www.itsnoteasybeinggreen.org/
Nice project. Just a couple of comments.
You brought the connections out of the same corner. One stub is really long and comes from the other end of the coil. I’d have cut that short. Cool water flows into the bottom, hot out the top. It would make filling simple too.
With this configuration you can go with a single tank, above the coil. Connect the bottom of the tank to the bottom of the coil, and top to top. It will siphon freely.
Check out a book called “A Golden Thread: Twenty five Hundred Years of Solar Architecture and Technology”. You will be amazed at how we are reinventing the wheel.
BTW the “large coolant holder” in the article is the compressor.
Best,
Tom
OK, but how will it work when it’s, say, 30 degrees outside? Will it get hot -that 100 degrees or more?
Then, can we extends the exit line into to 25 feet of tubing, wrap it around the back of a fan for a space heater?
( The AC version of this works great, by the way. I’ve had one in my garage for months. Let’s me tinker away in 75 degrees when it’s been 90+ outside!)
Take care,
Joe
one of the better thermal energy usage i have seen blogged.
i would really like to see someone to put up a step by step of actually installing it into the water system in their house.
the these low costs, it isn;t worth getting a commercial unit, just to get the IRS tax credit.
Thanks for all the comments let me try and answer a couple of questions all in one comment.
This was never meant to be a commercial system, or to be used in a real home. There are many commercial systems available for this that work much much much better than mine.
For pools, you would not want to use copper pipes, as chlorine would tear them up pretty fast. Most pool heating systems use a heat exchange system, or black plastic contraptions.
I actually work for a company that builds and installs renewable energy systems on homes. We do solar thermal, pv, and wind turbines. We would NEVER install something as DIY as this on any home, it is not meant for winter use, or anything like that.
Commercial solar thermal systems are designed to work in the winter.
The reason this panel is not “perfect” or “optimized” is because I wanted to see what was the absolute cheapest panel that could be built that would still work really well.
Thank you so much for all of your interest.
If any of you have DIY projects that you have done, and would like to put them on The Sietch, let me know, we are always looking for more people to add projects.
Thanks.
That. is really cool! I’ve always wanted to do some DIY stuff too, but they take so much time!
Using the refrigerator part was brilliant….well done
Could you possibly give some specific instructions for these projects ? I can invision most of this, but accuracy would be nice. Please post specific instructions for the dummies…. Thanks and keep up the good work.
I guess its kind of hard to give “exact” instructions on this project as it really depends on what materials you found, basically build a small box to hold your collector with glass on one side, and backing on the other.
The finished project as shown is about 3 feet by 2 feet and about 5 inches thick, i used about 10 feet of air hose, and the refrigerator grill was off of a smaller “half fridge” model.
Other than that the wood was 1 inch by 1 inch framing from an old couch. I used long wood screws to hold them together, and the door mat was cut to size by holding the fridge grill over it and making sure it would be large enough to hold the frame and the grill.
Hope this helps.
Thanks again to everyone for all the comments.
Don’t use tinfoil. You are reflecting much potential heat back out. make the box insulated and line the inside with something black. Roofing materials work the best as they can handle the heat. You will find you will get much hotter water as it will increase the internal air temp.
http://www.flickr.com/photos/nitroburn/175266083/
Check out the solar water heater I made for my pool. Works great. That 77L holding tank gets very warm and the pipes average a 10c difference in tempeature up their length. You can feel the warmer water come out of the hot water inlet from the inside of the tank.
What would happen if you ran another fridge grill in line with the first one? would it increase the temp of the water or give it a more even temp? would it make any difference at all? I am asking because i really like this project.
In theory you should be able to get hotter water by running these kind of panels in series jason…that is how commercial solar thermal systems work.
Nitro: I will try it without the foil, but our testing showed the foil actualy made it hotter. More testing is needed obviously. Cool pool heater.
I think what may be happening is that the foil is bouncing the light onto the back of the refrigerator grill. Light is therefore hitting both the front and back of the grill and turning to heat. This may heat the grill faster than relying on the heated air around the grill, which is what would be produced with a black backing.
It would be neat if you arranged a few cheap mirrors around this thing to see how much of an increase you could get.
Marcus/Nitro I do talk about that in the article, it seems that the foil is in fact getting the sun onto both sides of the grill. We are going to be adding some mirror (which i just found on http://www.freecycle.org ) and see if we can get this bad boy smokin.
I just purchased a box of 1″ mirror tiles for my solar concentrator.
Have fun!
Also, the black backing might be more effective if the box was insulated. It could be transfering the heat through the backing rather then to the collector and thus making the reflective surface more efficent for transfer in this case.
The goal of this panel was to make it work well for the least amount of money, if i can find some old foil house wrap i will coat the back with it and see if that would work to keep heat in.
Nirto could you please contact me using the contact form, I really want to talk to you about teaming up on some stuff. Your projects are great. I too have a bunch of 1″ mirror panels and am thinking of using it to concentrate more sun on this panel, or a future design.
You really do need to understand more about heat and light
Nice project, but heat can pass through glass too, FYI. That’s actually the principle you are using.
Perhaps my wording in the project was poor, what I mean to say is that infrared radiation (heat) has a hard time passing through glass, the principle I am using is the same as what happens in a green house. The light (most of the spectrum) passes through the glass and is absorbed by things within.
These things then begin to heat up and emit infrared radiation, this radiation has a much harder time passing through the glass (glass is an insulator) and thus the green house heats up.
In the thermal panel, the fridge grill is the thing absorbing the light (its black) and the glass keeps the heat from escaping too fast thus the water inside the tube gets hot.
Perhaps a re-wording of the project is needed…
I haven’t read all of the comments, so I may be addressing a question that has already been answered. Joshua, you asked about the problems of heating the water to about 170 degrees for your pool. We have an indoor pool - so it never gets really hot because it’s shaded even in 100 degree weather. At this point we have just snaked some hoses around in an old tire and covered it with glass. We can get the water coming out of this to about 120 degrees but are still only heating the pool to about 84 degrees. The reasons being, among other things, that the water is constantly moving, we aren’t picking up any heat during the night, and we’re heating about 15,000 gallons of water so it will take a long time to raise the temperature in the pool each degree that we gain. We just hooked one end of the hose into the hose from the pool vac( where it attaches to a hole in the wall of the pool), ran that end of the hose out the patio door, then ran the water through all those hoses and in the patio door to the pool water again. The pump to run the filter circulation system is moving the water. Have taped up the edge of the patio door to keep the heat in the pool room (because we need to keep the temp in the room a few degrees above the temp of the water to avoid condensation). It’s very crude, but sort of working. We’re in the planning stages of a better system. We are looking into using old water heater tanks inside black boxes. We’re wondering if an old propane tank would work as well and make a much larger holding tank. Or is there such a thing as too large? Too much of a good thing? I’m cautious about just how well we could clean out a used propane tank and whether I want any of that residue running through my pool, even with a filter system. Also, we are debating the black vs. foil lining in the box that will hold the tank - and I assume hoses. My husband wonders if two panes of glass are good, would three be better? Would two panes be OK even if they are just double layers and not thermo panes? What about rocks on the “floor” of the black box to absorb heat and let it off slowly over the evening hours? We live in Missouri so we have plenty of rocks! In this case I am thinking the rocks should be laid on something black. I am pushing for a very dark brown metal box made of the same sheet metal as the trim of our house for cosmetic reasons. Will this absorb heat about as well as flat black paint? We could always go with the brown on the ourside and still a flat black inside the boxes. These last questions are to anyone who has an answer or opinion. Thanks a bunch for your help.
I would stay away from the rocks, people have been trying the old heat rocks thing for a long time, it seems like such a good idea, but in reality they almost never add anything to the project. I would say try to trap as much heat as possible in the water from the pool itself as water is a very good storage medium for heat.
Also the tube through tire idea is brilliant. Some things to think about, two panes of glass are better than one because they are insulators and tend to help keep the heat in, but they also block out the sun rays, so as you add more pains of glass they start to block more and more. Its a good idea to keep the pains to no more than two.
Also if you want more heat you can always just create more of your tire/glass creations and hook them up in a series. In this way the first one heats the water a bit, sends it to the second which heats it more, and so on and so forth. In essence adding more solar thermal “panels.” This should get you more heat.
You can use tanks as storage but if the tank is large it will take a long time to heat up the water inside, thin tubes or pipes exposed to maximum solar radiation will heat up the fastest. But thin tubes will not carry much water, a compromise is to have tubes of around 3/4-1 inch. This allows a lot of water to flow but also a lot of surface area for the water to warm up.
The better you insulate the system the more efficient it will be. I imagine if you made the system too large, it would heat your pool to a temp that was not fun for swimming in, perhaps you can have a large solar sauna :) But I would not worry 15,000 gallons is hard to get that hot.
I would suggest that before you go building anything else you try a couple of your tire heaters in series, they are simple to make and its always easy to find tires. If one gets you to 120 try three.
I’m not particularly worried about heating our pool too much. But would like to be able to heat it enough so that the lines don’t freeze in the winter and keep the pool water and pool room above freezing, too. May have to turn on the wall space heater to keep the room above the water temp, but it would be nice not to have to use up a lot of propane to heat the water. We have been closing the pool down and just keeping it cold but running the filter system from Thanksgiving through April, depending upon weather.
Our idea is to heat the water through the hoses ( we have a lot of black hose) and mostly use the tank for storage so that we can continue to pump warm water into the pool for a while after the sun goes down. I think you’ve talked us out of the large (500 gal) tank. Dave found an old heater tank that he says is larger than the 50 gal we have in the house and I think we still have an old 50 gal one laying around. So if one tank is good we will do it again and run them in tandem for more and hotter water storage. The black hose we have is a little smaller than garden hose so restricts the flow somewhat because the yellow and green ones are regular garden hoses. Don’t know if that would be 1/2 in and 5/8 in or 5/8 in and 3/4 in. Probably won’t do the lots of metal tubing thing because you all seem to be into copper tubing and that’s way too expensive to buy and we don’t have any layring around here. We are thinking of about a 3 ft by 6 ft box and trying to find an old patio door to lay on the top. That would make it all one piece of glass and easier to seal. Plus if we’re lucky it will still have the thermal seal intact. Otherwise we have a lot of tempered glass in about 3X4 ft pieces but that will be a little more work to fashion into a lid and to seal. Also wondering about just one layer of that glass and in the winter covering the glass with insulation at night so we can capture heat during the day and hopefully hold some of it all night in ase we have to build something out of the smaller tempered glass pieces. Not sure about the coiled hose - whether it will go in the box with the tank or have it’s own box and run the hose from there to the next box that has the tank. We will butt these boxes up against the back wall of the house and against each other - run in a row along the back wall ( south side) so there won’t be much or any hose exposed to the elements.
Oh, also… I am not going to encourage Dave to line a bunch of old tractor tires up in our back yard ( OK, so I almost said “MY” back yard). I am trying for something with a little more eye appeal.
Now we’re just waiting to see how the debate of black interior vs. foil or mirror comes out (he’s leaning toward the reflective idea). Will keep you informed as we progress with this project. If anyone has any more suggestions, throw them out there. We will listen and process everything and anything that anyone comes up with. Thanks. You’ve helped us get several steps along with our solar heat system.
By the way, I really liked your refrigerator solar panel. And since you’re thinking just an experiment or something to take camping I think you’ve got it pretty well where you want it. You don’t need to try to haul something too large and unwieldly on a camping trip. Great idea - and I can’t fault the cost factor at all!
Hey ‘Naib’, glad to see you’re still working on your solar thermal panel. It’s been a while since I assisted you (limitedly) with the first draft. Hope you’re doing well.
Still working on that solar pool heater. Got a larger tank and painted it flat black - bu no box built yet. Will take some pictures and keep track for you, but right now we have some health issues with my 83 year old parents in Iowa so I will be making a trip up there and will be a bit before I get back to you. Pool is now holding at 86 degrees and I don’t really want it any warmer, but if we can harness more energy and more heat it will be great to have this winter. Back attcha soon.
Judy and Dave
Another parting of the minds. Dave wants to make the lid and the front of this solar box out of glass. I am thinking just the lid with the front being a solid, well-insulated wall. Anyone have any suggestions here? Has anyone done a solar box with one wall also glass? Would this let out more heat or let in enough more heat to even things out or actually gain some heat ? He is also thinking reflective insulation on the interior walls. The tank is flat black and will take up most of the box. I think he is planning to make it large enough to coil the black hose inside the box, too. So, I guess what I’m getting at is that the reflctive insulation might normally just reflect the light and heat right back out the front of the box, but with a lot of the interior being taken up with the flat black tank the relfection probably wouldn’t get past the tank - except maybe where the hose is coiled. Help! We’re up for suggestions. Thanks.
Judy and Dave
Hello: Great idea! I’m not the best at building something,but you show how in a simple way. My question is, how do I hook this up to heat my pool water. It is some were around 12,000 gals of water. Thanks Thomas
I wonder whether the one-way glass like the police use in interview rooms would work better — obviously harder to get hold of scrap. The idea would be to reflect all the light and hopefully heat back in towards the heat collector.
Thomas: If you wanted to heat a pool you would have to build a much larger version of something like this, probly out of black plastic tubing, and then hook that up to your pool this small test design is not large enough to heat that much water.
Mark: good idea, but the foil that they put on that glass would as likely bounce as much light away from the panel as trap it inside. It is a fine balance between letting light in, and letting light out.
Good work. So many people on the web TALK about projects. So few do. And, two projects, the heater one and 2, even better.
Ignore that Mikie guy, he does nothing, and, one of his comment was factually wrong.
I look forward to your future work. I nitroburn is also a prolific worker, hopefully you two will corroborate in the future
Hi, do you know of any commercial kit set units you can assemble yourself for your own roof to heat your house water? I live in NZ and solar water panels are really expensive…would like to build my own but lack the confidence…could maybe assemble a kitset.
I am sorry Kiwi I do not know of any kits that you can buy, however you could easily take the instructions on our site (and others) and create a low cost solar thermal option. After having worked for a company that installs the commercial stuff I can tell you they are worth the money.
Many places have rebates and incentive programs that help consumers pay for solar thermal panels, I would find someone in your area that installs solar thermal panels and ask them if they know of any such rebates or grants.
Has anyone tried this with tubing other than copper?
I have access to plenty of thin walled plastic tubing and was wondering how less efficient this would be.
e.g if the panel was say 25% bigger would this balance out the use of less conductive tubing?
Or am I missing a significant point?
Thanks
Mick
So long as the tube is of a dark color it would work just fine. You may want to check out our most recent entry for solar thermal projects
http://www.thesietch.org/projects/solarthermalpanel3/index.htm
It uses plastic tubing and works very well.
making the panel 25% bigger would just make it work better.
Another problem with copper lines and chlorinated water - the chemical reaction will cause copper to dissolve into the pool water with the result being a lovely head of green hair!
I’m currently weighing options for constructing a swimming pool heater along the lines of the water heater illustrated here. My plan is to use an automotive radiator encased in a glazed, insulated box. The inlet and outlet are about the same size as the pool pump supply and return lines which would minimize flow restriction, but would tend to cause the water to heat less… multiple passes or multiple panels connected in parallel (parallel creates less flow restriction but will be more difficult with the auto radiator design). I like the 3rd generation panel design too… my dad and I came up with that idea about 35 years ago! :)
NIce project, though I wonder what use the water is given it’s possible contamination by passing through an old used freon coil.
I think I’d make a few modifications.
- Use multiple coils, stacked for more flow and capacity. Probably 4 in series parallel. 2×2
- Use a black backing. Maybe roof paper or black shingles.
- go to a sealed system with a heat exchanger and (solar powered?) pump.
- A heat exchanger could be as simple as some copper tubing wrapped around some water pipe and wrapped in high temp insulation, to a commercial model like http://www.sunearthinc.com/suntherm.htm
- Add an old water heater for a storage tank. out from the bottom, return to the top.
Tachyon: The only thing that would be inside an old freon coil is mineral oil (freon is lighter than air and any left would instantly vent out). Mineral oil is non-toxic and wont hurt you.
as for the modifications that sounds like a lot of great things, it seems there is some debate as to the most effective backing black or foil.
I was trying to make this project as dirt cheap as possible, so doing a lot of the things that you suggest would increase the price a lot. They are all good suggestions, I just wanted to keep it as cheap as possible.
I think you should have used the fridge door to avoid build a box around your panel… reusing more parts is a good idea and a gain of time
Thank you for your projects
Wow! what a great idea, the door is already insulated as well…Perhaps I will try this out as soon as i can get my hands on another fridge.
Thanks for the tip :)
I have just discovered this site and this project. Lots of good advice here to apply as well. I can’t wait to build.
Reuse as always is the best recycling.
My wife and I have a small agricultural interest in which I intend to apply a variety of alternative and renewable energy techniques to take it off the grid and maybe even give a little back. Energy independance combined with healthy food for people is the goal.
Excellent concept model. Will experiment with an indirect system, eg; an indirect hot water cylinder using its coil to transfer the heat to raw water, which can then be used. When I trained as a plumber, gravity circulations were taught. This information can still be found in old books. You can then calculate circulating pressure, resistance of pipework and if it will work, before you spend hours making something. Good Luck.
Since the rubber mat you found had a metal plate in it, it might have been an anti-static mat that is used by people who work on electronics/computers.
It removes static electricity from the person so they do not fry electronic components by touching them
excellent articles
thank you
I would think thermo pane (double glazed) windows would be a bad idea because it often is coated to reduce the amount of infrared light entering a house (the rooms stay cooler and upholstry does not fade as much).
this would keep the heat from entering the collector in the first place.
I think the glass is also to keep heat from leaving through convection or conduction (a cool breeze flowing across a hot collector removes some heat.
I would like to try it by covering the collector with something like roofing tar so as to try to convert as much light as possible into heat by absorbtion.
ya know, with a measuring tape and a skill saw, that there could be a super collector, maybe a nice black sheet of metal, or even corrugated tin aligned to center the curve into a focal point at the center of your carrier lines (that would super heat the water concentrating the energy directly into the line). ever seen any old scraps of good paintable tin around your neighborhood? Plus, you are getting the most expensive piece of hardware, the coil, for pennies, pre bent and pre braced with addition of the fins that actually help reduce heat loss. hmmm… now that rocks, and cleaning up the dump, and thats that much more ore that isnt melted with fossil fuels… not bad. kudos
another note, tar melts… solar heat gets very hot on black… use metal, the more reflective the better, glass traps the heating rays to a great extent (not heat)
wow, should have read more before posting, all critique. well, for the money spent, you did great and for the purposes, perfect. I know there are alot that can improve on this idea, but the very best thing i see is the recycling of the refrig coil. awesome and simple. for the price, you can connect alot of these before touching the cost of making one 24 x 36 . i am guessing that is close to the size. and the loss between units wont be much, insulate em… just keep that “heat goes up” happening as much as possible and the pressure will do the rest. there are of course two real good ways to get the heat into the pipes. using the flat metal collector directly attached, or even hotter, centering the pipe into a convex reflector. but for all the critique. its still talk, this here is action and doing anything is better than nothing… get busy everyone else
What about using a fresnel lens under a pane of glass?
Dave: That might work…if i can get my hands on one I will check it out. I have another plan that I have been working on and should be ready some time this summer (its 20 F outside right now, not the most fun for outdoor projects) that might use something like that.
This gives me an idea. Does anybody think they could build a solar refigerator. If you can or already have post a link up here, please. Thank you.
i think this is great please email mail me updates on this email is den610@hotmail.co.uk
Hi
This is awesome. ‘eco’ mentioned using the fridge door - but what about using the whole fridge? Mount a water cylinder in there (eg black plastic) and the panel below, arranged to thermosyphon. The fridge should provide a great insulated box for the hot water. (If it was a bar-type beer fridge, with a glass door, you could heat it directly too!)
I love this message board. I have a few ideas to contribute. There has been some debate as to whether a black background or a reflective background would be better. Well, the whole point is to maximize the surface area that is being heated by radiation. A painted flat black aluminum plate should could be the best option here, but only when the copper coils are resting in contact with it. If there is no contact, then a reflective back is best. Aluminum has great thermal conductance, although black steel would be fine too. Reflective backing is used when you are trying to reflect solar radiation back onto an object, however, evaporator tubes have little surfac area, so you are better off heating a large conductive area in full contact with the evap. coils. Just my two cents. I am a mechanical engineer, but no expert by any means.
Somebody else suggested using coils in series, this would make it difficult for thermal syphoning (assuming the the coils were all ’spooning’). I would think you want them in parallel, that way you would get a greater flow also. I love this project, i am going to try this myself. I have two old fridges that don’t work.
thank you for your kind words fing, just remember to have the freon removed from your fridges before you use them for any projects, don’t want to make the hole in the ozone any bigger.
If you have any luck send me some pics I will post them on the site.
good luck!
just saw this project a few days ago and cannot stop thinking about it. I’m definatlet gonna have a go at it, if only to wash my hands in warm water while at my allotment. Great work and explained in laymens terms which is also great….. Lol….I’m confident in my abilities to get one of these up and running in a few weeks, as i have loads of other things to do at my allotment first so it can wait, while i collect all the bits i need…. Thanks man..
“My very basic understanding of solar heating is that we want lots of surface, and a mass that would absorb the energy quickly. How about if you cast the cooling tubes and fins in a thin (one inch) layer of concrete and paint it black? Lots of surface area and it is in direct contact with the tubes and fins for more effient transfer of energy.
Then use a solar powered pump to circulate the water, they are redially available from the artificial pond companies. I would wire it direct…only runs when the sun is shining.
Bob, You are right in having a black background, it is the collector surface area that matters most. However, I don’t think concrete is an ideal conductor to transfer the heat to the coil. A metal (preferably copper) plate painted black would be best I think. The solar pump is a novel idea. What if you also linked the pump to an old thermostat that would only allow the pump to run when the water is at a set temp, that way the water is being allowed time to get hot enough in the coils. How much are those pumps?
I have had a go at this with some amazing success. What I have done is built a metal tray on top of my shed roof the same size as a double clazed window I have. The tray is 6ft x 5ft and 5 inch deep. The coil is made of copper tubing and fills the tray with each end of the coil through two drilled holes in the side of the tray.. I then encased the coil in road surface tar that fills up to one inch below the rim of the tray. The double glazed window is then screwed to the top of the tray. Water is pumped in from a large rain water collector through a modified pond and UV filter into the solar heater and out the other side when the water gets to 60 degrees. On the outlet I have an old thermostat linked to a outlet valve which is also linked to a switch on the solar powered pump that contains a backup battery. I have probably not fully explained how it all works together. But it does work extremely well. It has a few quirks that need sorting out but once I have it working 100% I am going to build one on a larger scale on top of my house roof and use along side my main heating system in the house.
Dave, take some pictures and post them!!h
Es una grán idea, además de que al leer los comentarios que te han hecho, se mejora la idea.
Estoy tratando de utilizar un sistema de calefacción de agua para la labadora en una zona rural, asi que esta puede ser una buena idea.
Gracias, y si tienes alguna sugerencia o proyecto más adecuado te lo agradecere mucho
las dudas que tengo es sobre el tanque que recomiendes.
cual es la diferencia de nivel que tienen que tener el panel con respecto al tanque.
gracias.
Gracias por compartir los proyectos!
Es una grán idea, además de que al leer los comentarios que te han hecho, se mejora la idea.
Estoy tratando de utilizar un sistema de calefacción de agua para la labadora en una zona rural, asi que esta puede ser una buena idea.
Gracias, y si tienes alguna sugerencia o proyecto más adecuado te lo agradecere mucho
las dudas que tengo es sobre el tanque que recomiendes.
cual es la diferencia de nivel que tienen que tener el panel con respecto al tanque.
gracias.
Approx translation for those without Spanish:
Thanks for sharing your projects!
It’s a great idea, that gets even better on reading the posted comments.
I’m trying to set up a hot water system for a washing machine in a rural area, so this could be a good idea.
Thanks, and if you have other appropriate suggestions or projects, I would be grateful.
The doubts I have are about the tank you describe. What is the difference in level does the panel need with respect to the tank?
Thanks
Nice project and presentation, thanks very much.
I really like the old refrigerator coil idea as cheap and convenient metal tubing, already shaped into a neat, flat rectangular area and painted black.
I also like how the originial function of the fridge coil is now reversed - formerly to lose heat, now its being used to gain heat.
Perhaps for safety sake you should edit your article to make the point about the unkown toxicity of the water flowing through an old fridge coil much larger, bolder, and red! There have been cases of poisoning and birth defects traced back to fridge coolant contaminated water.
Rubber is a reasonably good insulator, but black rubber will tend to heat on the inside of the box and release it on the outside - more so than if the rubber is a light colour. A cheap solution might be to stick a layer of foil onto the back of the rubber.
For colder, cloudier weather, your reflector foil would be better painted a matt black (only on the sun-facing side) to absorb all that light energy rather than reflect it off. To conduct heat from the blackened foil to the tubing it must be pressed up against it so that they are in close contact. Doesn’t matter if the blackened foil gets a bit crumpled doing this.
Or, perhaps even better would be to leave the reflective foil as you have it and just lay blackened foil (but blackened on both sides) on top of the tubing. This blackened foil layer would do all the work of capturing the solar energy and then conduct it as heat into the tubing behind it. The reflective foil left in place would then become an insulator and reduce heat lost through back of the unit (as long as that one is not touching the tubing).
If black paint is too expensive, you could try blackening the foil with soot (just an idea, don’t know how it would be best done).
Fingallion
I was figuring on the thermal mass of the thin layer of concrete. The concrete would hold heat not transfered to the water. Using the refridgerator coil as the tubing I would strip the paint they put on to improve contact. Fluid contact would be good …how about immersing the coils in used oil?
I wonder if pulsing the water would have a benifit. Maybe use a slow piston pump, on it’s intake cycle it would not push water through the tube, then if it is sized right it would empty the tube by forcing a new batch of water in. Water sitting in the tube could absorb more heat than just passing through, although I am sure there is a fine line between long enough and too long.
I agree the copper plate would be better but copper is way expensive now and not many people have soldering experience…there would be some wierd things (stresses) happening to the plate as you soldered the coiled tube to it.
And the Naib is trying to develop this wiht low costs.
I think used motor oil is probably a bad idea seeing as you can’t tilt it to the sun, also I am guessing oil is a pretty bad thermal conductor.
As far as I can see, all commercial flat plate collectors have a black copper or aluminum sheet attached to the pipes. I saw on some DIY site that you can simply tie-wire the coils or risers to the plate and get almost as good a thermal connection as if you welded them or soldered them. 18 gauge aluminum sheeting is not too expensive.
Here’s an interesting idea, use a single panel hot water domestic radiator painted black as your complete collector!!! You can buy used ones for next to nothing!! Essentially you are using it in reverse.
Nevermind the radiator idea, it would work but they are not cheap like I thought. Also flat panel rads are hard to find in US.
Hi Could this system be adapted to heat pipes, perhaps in some sort of a circular system?
Paul: I am not sure what you mean, but the heated water output can be used to heat just about anything you want to make hot. Either by simply putting the hot water over what you want heated, or using a heat exchanger system.
Could anyone comment on the A/C version mentioned above in post #17? How would this work?
I’m sure a lot of people would be interested in cutting their summer cooling bills. Or at least experimenting with it.
If you are interested in cooling, then maybe something a little off topic. When you dig a hole a couple of feet in the ground, the temperature is pretty constant all year round, 40 to 70 nationwide. I am guessing the midwest is 40is all year round. You could bury some pvc or copper coils a few feet down in your back yard and have water pumped through them to some kind of heat exchanger (possibly an old non working window AC) and let the fan blow air across the earth cooled coils. I don’t know if this would really work well, but something to think about though. The earth is an excellent heat sink. Anyway I reallise it is off topic but it is an answer to post 84. I also think we are all on the same page if we watch this blog.
Thanks for the reply Fin.
Yeah, there are commercial systems like this. I think they’re called geothermal. They go several hundred feet down into the water table. 40F sounds a bit extreme…I’d be curious of any place that gets that cold…I’ve only ever heard of 60-ish.
Anyway, I was just curious about someone running this experment in reverse for cooling, or what the poster did to cool his garage. My garage I have no problem with…my basement never gets above 70.
Yeah, it is geothermal I guess, but the comercial units essentially are substituting the ground for air for the purpose of condensing refrigerant with huge efficiency… either by going deep to wells or using long shallow trenches 48″ deep (approx frost line). I was just considering a low budget way of cooling water by a few degrees.
Has anybody made any progress with the solar collectors?
wow you guys are amazing, how do you think of using that much unwanted stuff and turn it into cool things
im building this for my science project
thankyou
If I take the piece off of a larger refrigerator and cut it into six equal sections, then take a 12 volt marine battery , use the six sections in one panel each section having in and out tubes, and run each section to one cell of the 12 volt battery. Will the heat from the acid running through the thermal panels charge the battery? And how fast would it charge and by connecting other batteries to the posts of that battery how many other batteries would the first battery keep charged. Keep the battery hooked to the thermal panel well ventilated to reduce explosive gases.
Gary: This system will only produce warm or hot water. It in no way was designed to charge a battery. If you want to charge a battery from the sun, start here.
If I seal my windows with black plastic will it help keep the house cooler in summer?
Great work!! Okay, so how would you modify this design to create a solar-powered “hotbox” for my backyard vegetable garden so I can grow vegetables in the dead of winter. I need to heat the soil, not necessarily water it.
Great work!! Okay, so how would you modify this design to create a solar-powered “hotbox” for my backyard vegetable garden so I can grow vegetables in the dead of winter? I need to heat the soil, not necessarily water it. I’ve heard of such a thing being incorporated into radiant heating systems by commercial manufacturers such as http://www.radiantsolar.com, but I want to try to do this myself.
Hi,
Thanks for the nice idea of using a fridge radtiator in a solar collector!
I am at the moment in a small city in Peru, Abancay, where I am helping to build a new school. We like to work as ecological as possible, but there is of course not much money.
Therefor, I used your idea to build a small demonstrator of a solar collector. The result can be seen in these pictures:
http://www.muzes.be/zon/zon1.jpg
http://www.muzes.be/zon/zon2.jpg
http://www.muzes.be/zon/zon3.jpg
http://www.muzes.be/zon/zon4.jpg
Here, everybody is used to taking showers with cold water, brrr! It would be ideal if we can include a simple solar colector in the school construction plans.
As you can see in the pictures, everything was build from costless material. Total bill: zero nuevos soles! The glass plate was a little small, but I found some bubble wrap to solve that.
In the future, I also would like to make it thermosyphoning. But I think the tubes are a bit narrow for that…
Greetings,
Toon
PS: Comments are welcome!
Very nice. you should make the backing black if ou can (metal if possible, possibly an old baking tray or fridge door as a source for flat metal), the whole plate and coils are the collector so try not to reflect any heat off them. The notion of using silver foil or white is no help to you whatsoever.
[...] are still rolling in but Toon, let me this interesting comment on my solar thermal panel project post. Have you built something inspired by what you read here at The Sietch? Or maybe you have come [...]
tash and I used this design for our science project with slight changes. it was out there for at least three hours in cloudy conditions and the water went up to 25 degrees celcius.
hiw do you think up these things?
You could avoid getting durty fenol rich water in your mouth, if you installed a small pumb like the one we use for Japanese min towers with stones and water in our rooms. You could also avoid the buckets if you connected the panel with the water supply by a bit of a garden hose. That would not add much to the cost, but make it really useful. I will build one in my summer hut for outdoor showers!
Nobody answered the fella earlier about using a old car rad for the solar collector. It is copper usually black hopefully water proof. Just enclose it in a solar oven box like the copper tubing. In this case you don’t want the sun to get all the way through the rad so would place it at a angle so light shines to almost the end of the rad fins. The insulated box and glass on top would keep the radiant heat in. I can’t believe nobody has not tried it. Maybe used car rads are more money than I think.
Very good project… Impressive… Though hard to believe that water could heat up to a boiling state - until you build the project yourself. One more problem is that some towns do not have a local rubbish dump. But hen again, you look for the closest one.
A black box with a glass front will heat the interior and air to about 250 f even in the middle of winter. How you transfer the heat to water or other medium is up to you. You get about 50,000 btu per day useable heat from a 4 x 8 foot panel. Solar gain is all about surface area, the more the better.
About the infrared and glass thing. Infrared is light that you can’t see. It goes right through regular glass almost unaffected. That’s both in and out. What you have to do to trap it is absorb it and make something hot. Black is good, but foil will bounce it right out which does nothing. Thermopane is fine as long as it’s not low-e thermopane which has a infrared reflective coating.
Hi
Very interesting information! Thanks!
Bye
Hi there,
As suggested by one commenter, you might want to do some more basic research. A very basic panel is a black plate with water lines attached. There must be excellent thermal conduction between the collector (black plate) and the water lines. The black plate is the collector, not the water lines.
Energy from the sun in the form of visible light is absorbed by the collector, turned into heat (the collector gets hot), and is transferred to the attached water lines. Many black surfaces are great at absorbing visble light and turning it to heat but also are great radiators of infrared waves (heat). This is where the glass helps. Glass is often reflective or opaque to infrared radiation so it traps it in the panel (reducing losses). The glass keeps the wind and cold air off the panel, too, which can rob heat as well.
Your foil, placed as it is, will reflect much of the visible light right back out the glass panel. This is very inefficient. Try making your coolector panel black and be sure to make a good thermal connection between your water lines and the panel. No tape! Its best if its welded, but lots of metal straps might be a cheap way out.
The foil should be behind your collector plate to reflect infrared radiation leaving the back of the panel. Behind the foil is the insulation. A popular technique is to used foil backed rigid insulation (foil towards the back of the panel). It needs to be high temperature!
Excellent use of recycled materials! Kudos!
Brian
hi, Tony from Hunucma Yucatan Mexico,
Your just what I was looking for:cheap, practical and investigative.
I´m gonna do it (the hot water tank). Also, I enjoyed your light sense of humor and honesty about your trials and tribulations.
You definitely have my attention. Oh, I almost forgot, here in Hunucma, this could turn into a community project.
Thanks a lot and keep up the good work.
Your student,
Tony
Tony: Thats great, please keep me updated on how it goes. You can make a solar thermal panel out a million different things. If you come up with something cool please send pictures in and I will highlight it on the site.
You mention you “already had screws” but at some point you did purchase them! But that is a good simple project. I live in Florida and recently purchased a portable spa and intend on using solar to heat it. My intent is to purchase a solar dc pump with a solar panel ($49.95) to run it and an automobile raditator to heat the water. I have already obtained a solid glass window and plan on building a wood frame using pressure treated wood for the box. It should prove to be a very simple task since I am the handy man sort.
My comment will be the umpteenth, but you need a black metal pannel, thermical coupled with the serpentine, in order to make it work decently. Moreover try to get a boiler with internal serpentine, make a dress of isolant material all around and feed the internal serpentine with the water coming from one or more panels, remember to add a pressure valvle to prevent breaks as the temperature increase over 100 degres centigrade, due to the pressure. Add a small DC pump supplied by a small fotoelectric panel, so water will flow only when there will be the sun. If you have a heater, supply its cold water input with the water coming from the boiler. Add an automatic mix (those for shower) before entering the heater in order to prevent the heater components from too hot temperature demages. With this system you will have all the confortable of the gas heater, your wife happy, and a considerable save in your gas bill.
I loved the idea of using old parts and saving money. I do animal rescue and have been looking for a CHEAP DIY project where I can dig up junk to make heat for shelters. I care for about 30 homeless cats a day (YES, I spay /neuter like crazy).
I did see the article for solar powered heat but need something portable (very), cheap and easy.
I am trying to think of a way to use your idea!
Any advice?
The question that was posed about the use of coils that previously had freon is legit. The system circulates lubricating oils that need to be flushed if the solar system is used for potable water. Acetone is perfect, followed by blowing air thru the lines. Acetone evaporates quickly, leaving no residue. Also, using aluminum foil or other reflective material is defeating the purpose. Fasten the coils to a thin sheet of black-painted plywood (preferably copper or aluminum) with the back insulated would do the trick.
I have revised my plans from a used radiator (chlorine in my spa would quickly make it unusable) to the use of CPVC which is for high temps, painted black and mounted as stated above. Will take photos when I start the project, and send them in upon completion.
To answer Joshuas question about his pool, simply tap the inlet of your pool pump and again after the filter with an inline valve to control flow thru your solar heater. Adjust the flow down until you can feel the warmer water coming into the inlet. Be sure to seal all fittings well or you will suck air in the inlet and your pool pump may slow down or stop pumping at all. If you are fearful that this might happen, put the low pressure side BEFORE the filter and the pressure differential will still give you flow thru your solar heater, just not as much.
To Gary Smith: You are spoofing us aren’t you? If there were any facts to heating a battery to charge it, no one in the summertime would ever have a discharged battery! The desert heat, coupled with engine heat would keep it charged fully!!!!
great job this is just want i need
Hi,
Some of you need to do a little more research into the laws of physics.
Brian wrote that glass is opaque to infrared. It is not and visible light produces very little heat when absorbed. Actually 52% of the suns energy is infrared radiation which is also light the same as visible light except we can’t see it. That is where almost all of your heat comes from. If glass where opaque to it the panel would never let any heat in.
Black is the best absorber and transmitter of heat. The trick is to collect the heat after it is absorbed but before it is transmitted back out.
Anything that is opaque to infrared (like low-e glass) will also prevent the heat from getting in. It will just bounce of the glass back into space.
So remember the heat you are collecting is infrared light before it gets to your panel. When it hits the black in the panel it’s energy causes the atoms in the collector material to vibrate faster. Now and only now is it heat. Before it got to your panel it was light energy and not heat energy. That is critical to good panel design.
Also good job to all of you. Solar is the future for us all.
Bill
Thanks Bill,
I always liked this blog as a positive concept for people to consider renewable energies, but at the same time a little surprised at the lack of basic understanding of how a solar panel actually works. The Naib has made a solar panel that probably heats water but should have used a black conductive backing instead of reflecting almost all of the heat out of the box with foil. The box and the coil are the collectors and should be both be exchanging heat with the water.
Reallistically this should lead to another discussion. These systems are very affordable to buy especially if you have any plumbing know-how. The actual panels are quite cheap. I know this is all about doing things from scrap and low cost materials, however, if we want to do anything meaningful we will have to spend a little bit.
Great Ideals, I need something at my cabin like this, but if its left for a week at a time without useing the water, what will happen, a boil over. And if not I would like to make this a closed system and a value on it so I can use it to wask dishes.
If I use you system and just have both hoses go back into the same barrel will that work??
Anchorage
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is it possible to have 1 bucket of water where the waters flows OUT from the bottom to the thermal panel where the water is heated and EXPANDS and then the water flows out from the top of the panel into the bucket of water but it just plunges from the top?? I do not know if this is can be done with thermo-siphon but if I do this it would be great! Anyone??
On June 24, 2006 Tom wrote:
“You brought the connections out of the same corner. One stub is really long and comes from the other end of the coil. I’d have cut that short. Cool water flows into the bottom, hot out the top. It would make filling simple too.”
is it possible to have 1 bucket of water where the waters flows OUT from the bottom to the thermal panel where the water is heated and EXPANDS and then the water flows out from the top of the panel into the bucket of water but it just plunges from the top?? I do not know if this is can be done with thermo-siphon but if I do this it would be great! Anyone??
OK I found a way to do it…it can be done with a waterram pump that needs no external power whatsoever ;)
(See below the section on Water Ram Pumps for additional comments regarding the original thread topic of solar thermal water heating panels).
In response to post # 118, here is a link to a site with a quick description of what a Water Ram Pump is along with several additional links to useful resources about Water Ram Pumps (the short answer: a pump that uses pressure within the system itself to pump water with no external power source):
http://journeytoforever.org/at_waterpump.html
And here is a link to a very technical site detailing how to build your own Water Ram Pump (they estimate $120 to build but looking at the photo I can’t imagine it really costs that much unless brass swing check valves are super expensive; the remaining 16 parts all look to be a couple bucks or less apiece at your local hardware store):
http://www.clemson.edu/irrig/equip/ram.htm
Now for my comments regarding the solar thermal water heating panel:
Heating water using recycled parts - great idea.
Heating water using recycled parts for less than $5? - priceless!!!
Yes, there are plenty of things that can be done to improve it as many of the previous critiques have pointed out. But as proof-of-concept, it’s an A+.
As far as the backing plate, and knowing how expensive copper and aluminum can be, my suggestions are:
1) Use aluminum roofing flashing (or even steel if you want to go cheaper without sacrificing too much efficiency). It’s very thin gauge metal usually found in a roll (but sometimes in sheets) at the hardware store. It’s thin so it can be easily bent into shape but not so thin that it will crumple, tear, and wrinkle like aluminum foil. If you’re lucky, you can sometimes find it pre-painted a dark brown to match flashing on homes; not black, but getting close. You might even be able to scrounge some from a construction site or contractor who has unuseable scraps leftover from a project. My concept is to adhere it or staple it (staple gun; not paper stapler) to a sheet of thin plywood on the backside for rigidity, then nail through it when nailing your frame together. Then just paint it black.
2) Check metal supply yards. Aside from being able to buy a clean sheet of aluminum or copper at a much cheaper price than a namebrand hardware store, many will often have a recycled/used scrap yard. If you’re lucky, you might be able to find a sheet of metal that can be used for your backing plate. You might also find a lot of other useful fittings, tubes, etc. that can be used in projects and purchased for pennies on the dollar. Just depends on how handy you are and if they happen to have what you’re looking for when you stop in. Just wandering around one of these places will give you great ideas.
3) Use a tin snips and a few aluminum cans. Cut the tops and bottoms off, make a cut down the long axis of the now open-ended cylinder, unroll it, and tack, staple, or nail it onto a backing of thin plywood. Then spray paint black.
4) I worked as a stage hand for a theatre group at one point. Sometimes we used a matte black, very heavy gauge aluminum foil for masking off stage lights. I don’t remember the trade name or the cost, but Google searches will find it for you I’m sure. It’s not heavy enough to stand up on it’s own in this application and would need a backing of some sort like the thin plywood I suggested earlier. But once attached to the plywood, it’s (a) aluminum and (b) black already. So no having to use messy, eco-unfriendly spray paint cans. And, since it’s meant to be put on the business end of a theatre stage light (a couple hundred degrees at least), you know it will hold up to high temperatures.
As for the insulation ideas, what about leaving an air pocket between your backing plate and the insulation? Do you think this would add even better insulating properties? So, going from the sun-side of the solar panel to the backside facing the ground, roof, etc. it would look like this in cross-section (apologies if the alignment is a little off):
SUNSHINE
||
V
__________________________ <– Glass
o o o o <– Tubes carrying H2O to heat
================ <– Backing plate
~~~~~~~~~~~~~~~~~~~~ <– Air Pocket
———————– <– Foil (or Foil Faced Insulation)
*************************** <– Insulation (if not using Foil Face)
^
||
REAR OF PANEL
The space would be accomplished by simply adding an additional shim layer in your frame. So instead of two frames (front and back) like in the original design, this concept has 3 frames:
1) One frame on the outer sun-side holding the glass above the tubes and backing plate.
2) Another frame (thinner than the rest perhaps) between the backing plate and the insulation layer to create the air pocket.
3) The last frame on the back of the entire panel behind the insulation layer.
Or perhaps dispense with the 3rd frame idea and simply make the back frame deeper than your insulation layer so there’s a gap between the backing plate and the insulation to further reduce conductive heat loss (as air will be the best insulator of all within the confines of the materials we have to work with and given that we can’t economically create a vacuum space behind the backing plate).
I live in Belgium so I think I can make use of this system to hot water in the month June - July - August. I have a water storage tank of about 100 liters and with the pressure provided solely by the water tank I make this water circulate in my solar heat collector I have built (and isolated very well). This system will be a closed system where I make use of the thermo siphon to make the water come back in the tank from the upper side. My problem now is that this water storage tank will be at a height of 1 meter from the ground and I at the same time I want to use this heated waterto take a shower. Is it possible to connect this water directly to my home so I can take a dhower? My problem is the pressure; is it necessary to set this water higher then my shower or will the how water be pressurized when it is mixed with cold tap water when showering??
If the hot water is clean you can simply put it right into the water intake for your other water heater…If it isn’t then you will need a heat exchange coil and you can run water from your cold water line through the coil, then into your current water heater.
I will use clean tap water to heat the water so that I can use it afterwards to take a shower or just for washing or drinking. Like you said ‘the naib’ I want to connect the water coming out of my collector to my water heater at home and so when the temperature drops below 60°C my boiler will have to heat it up. The temperature can drop when the collector as heated up the water till the evening and you haven’t used the water till the next day so the water cools of inside your storage tank or boiler. I want to constantly run the water during summer and warm days but in colder days I want to turn the tap so there is no water going to my solar collector. Instead I then want to use tap water to fill my boiler. I want a system that checks if the solar system is being used and if not, automatically turns on the tap water going to my boiler.
…but for this I need my boiler to give me a visual of how much water is in it; for example if I have showered and the boiler is empty I can turn on the system using my solar collector to heat water
yes yes. brilliant, i am down in mexico and we need a really simple system like this to avoid buying cylinders of propane.
my water heater is 40 litres, so i want to suggest an indirect system from yours which can then heat the water in an insulated tank. guess this can work?
also someone suggested rocks to retain heat for when the sun is not shining. interesting that the super super high tech solar plants in the usa (see solar thermal on wiki) are using molten sand. there must be ways to retain the heat when the sun is not shining.
can you progress this to an indirect system, maybe without the use of pumps?
i feel sure that a simple system like this can replace the gas water heaters here in my small town. sun is not a problem but commercial solar heaters will still cost too much for most people down here. no grants or rebates either, but no rules and regulations either - well not that many : )
you have helped really inspire me and we are looking for old refrigerators. thanks a million. jonathan
I live in Italy where this sort of technology is still ’space age’ and I’ve found this article fascinating!
We’ve finished having a pool built in our garden and I’m thinking about making some simple panels to warm the water faster in the spring.
A few points and questions:
I think the insulation in the panel is extremely important and I’d like to use a slab of polystyrene or similar as backing. This should improve efficiency. True?
Any idea how important the gap is that’s between the glass and the tubing? i.e. making the panel deeper?
Since I’d like to keep it as simple as possible and have the pool water pass through the panel, could I just use a black rubber hose and avoid the need for a separate heat exchanger? I assume that the chlorine would corrode any metal.
Steve
Wow, good job. i will attempt to make one of these soon and will probably document it on my website.
My sister lives in a small off-grid home, and I recently installed a small solar powered system for her. I think making some of these will be my next project !
( http://www.techienation.com/?p=21 )
take it from a physicist ( although this is pretty straightforward ), the back should be conductive ( a couple of layers of aluminum foil should do ) and the backing behind the foil should be thermally non-conductive so that the heat wont escape out of the back of the panel, so good choice on the rubber. Also, it would help a lot if the conductive back was painted black ( so spraypaint the aluminum foil black, basically ), keeping in mind that you want matte black NOT SHINE-Y! so re-spray the ‘frige coils. Lastly, I would advise staying away from the mirrors, you’re better off just building a bigger box ( even if you use the same coil as before ). If you use flat mirrors then your efficiency will be low and change greatly as the sun moves across the sky. You have to use a parabolic mirror-based design (as is done industrially).
Very Well said!! thank you!! its freakin’ awesome!!
Can i get your Email so that i can ask some questions, since i alrdy decided to create it for our project thankss!!! or please mail me ur email at jjad16@yahoo.com
thank you!!!
very well said!! its freakin awesome!!!
Please can i have ur email so that i can ask some important mattes regarding ur Project!! please since i decided to make that one!!! plz let me know also ur name so that ur name will be greatly appreciated thank you!!
plz mail me jjad16@yahoo.com
You’ve inspired me with this article and I intend to have a go at building a similar, but larger system around October (I’ll have cash then).
I live on a narrowboat in the uk and having recently installed a PV panel would like to heat one of our two 12 gall calorifiers with a similar system, I’ve got access to all the materials -kids like throwing fridges in the canals here- and will just need a pump (it’ll be laying pretty much flat so no thermosyphon) and expansion vessel.
One thing of note is that we travel through urban areas sometimes and get bricks thrown at us so we’d rather use plastic (i’ve a supplier of 2mm acrylic sheeting) for at least one layer, I intend to “double glaze” it. Would I be better using glass or another sheet of acrylic underneath it?
Also there’s some details around the switching gear I intend to use for the pump here… http://www.canalworld.net/forums/index.php?showtopic=16590&st=20&gopid=260601&#entry260601
Hello Smelly
I would suggest that this system might not be the best for use in a home (even one on a boat) simply because it is pretty flimsy, and could break easy. You would most likely get better results with a commercial system, or one made from more robust parts.
As far as people throwing bricks, perhaps you could put up some sort of netting to catch debris before it hits your panels, as a brick is going to go through just about anything plastic or glass.
The plan is to de-flimsy it as I’m installing. Although I’ll use the fridge matrices I’ve got loads of plumbing kit as I’m fitting the boat out myself so it’ll certainly be a lot more robust!
The commercial systems seem to use evacuated tubes that’d be even flimsier and they’re fixed. I don’t know whether you know the Uk canal/river system but some bridges are very low so it’ll need to be quite quickly removable and this won’t be amenable to a net over the top. At least the acrylic’s pretty flexi and should take most of the energy out of any projectiles, other than those that’ll otherwise kill my PV panel as well.
I built one! bad summer in the uk but I am confused as to the backing? silver or black? I assumed the silver backing reflected heat back onto the refridgerator back panel? I would have thought a black backing would draw heat from the box(out the back by making the back hotter) Well in a brief moment of sun it thermo syphoned when the bucket was nearly higher than the panel. The glass cracked though! It was pushing out steam and HOT water. When I pulled the pond airline pipe off the inlet(top) of the bucket and lowered it to syphon out it raised the water temp by 30C.
Water in at 27 out at 57c and it was about 28c air temp that day.
If left in the collector for a while it was 40c higher.
Although I made this for nothing but materials I had, it only flows a small amount due to the thin pipe so will make one from 10-15mm plastic pipe, gravity fed from pond filter and back to settlement tank(not pond directly)
Also gonna make the space heater out of cans for the shed or greenhouse!!!