Has anyone here ever tried... (PAH)

Dave Yates (PAH)

I built one about 20 years ago using two sheet metal boxes with ductboard sandwiched in the void spaces and used 3/4" slant fin BB elements, which I spray painted flat black. Worked by gravity circulation.

My thinking was that the aluminum fins would capture the sun's rays at almost any angle. Knowing what I know now, I know even less than I did then(G). Anyone here ever build your own panels? I'm tempted to try this again, but I'd sure appreciate your input before investing my time & money if this doesn't work very well.

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Larry Weingarten

finned tubes

Northstar Gardenia makes the copper fins used by collector manufacturers. I was able to order them up to 20 feet long. How about making your own headers and box but leaving the tricky fin stuff to tricky fin folks?

There was, in the 80s, a commercial collector using refrigerant and baseboard style finned tube. Its measured performance was not much different than the normal configuration.

hydronicsmike

When I was an apprentice...

...my boss at the time had me build a couple of smaller panels to his specs. We were using 1/2" copper to build a register with 4"OC spacing. The registers were soldered together and we added black metal plates (like heat transfer plates, just a little smaller/narrower). The registers were then installed in a metal box the size of our final solar panel and then we filled the bottom of it with insulation. The top was finished with a heavy duty tarp. - Basically, a half baked job, if you so will.

The panels worked not too bad actually during the hot summers in southern Germany. In fact this panel worked so good at the time, the boss had some of those made up in Poland afterwards. The boss was all about making money.

Then, one year or two later, on a harsh fall evening, we had a bit of hail storm. - .

Need I say more? Anyways, I remember the boss getting into a bunch of trouble over this as we had to re-do a bunch of those panels. This time with something more solid than tarp. We used some type of plexiglass (spelled right?) instead.

In the end of the day, I don't think we ended up saving a lot of money by building our own and having to go through the troubles and headaches afterwards. But had we made the panels without the tarp to begin with, it could have been different. I will never forget how angry a couple of our customers were at the time. Sure it was the weather that damaged our self build panels, but properly manufactured panels withstood the weather.

I guess we learn from our mistakes. I would like to add that the new covers worked and didn't get damaged by weather afterwards...at least I never heard from it again and I left the company about 3 years later and after my apprenticeship was done. But those panels couldn't even come close the the efficiency that todays manufactured solar collectors run at. And in all truth and fairness to the customer, I would never sell a selfmade panel unless it has been tested and proven at my own show for at least two years.

Mike

ScottMP

Dave

I tried to draw something up quick but I am off to Germany.

I want to build one for my kids small pool and sit it on my garage roof. Mt thought was a old glass storm window with an insulated box for it to sit on. One inch of foam board and then 1" copper header with 1/2" copper runs across the panel, like a ladder. The more I think about, I might start 1" and two 1/2" runs to another 1" header, drop down to another two 1/2" runs, and so on. That way the water would have more contact time.

I will draw it up and talk to you when I get back.

Scott

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hr

A couple methods

You could use some 1/2 baseboard fin tube element, or ThermoFin transfer plates.

I have a bunch of 21 sq ft Suncatchers for sale, at 80 bucks each, hard to even come up with parts to build your own. Especially the glass!

I believe Wolverine Tube and Brass sells finned copper tube also.

hot rod

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bill clinton_3

Solar collectors


Back in the seventies, I designed and manufactured my own solar collector using an approach very common then: extruded aluminum plates: then referred to as "solar snap fins". My design was a knock-off of the one Reynolds Aluminum was marketing except that it had tongue and groove edges to make the plates lie flat. Reynolds didn't mind my knock off: they extruded it for me.

The same product has been reincarnated for use in radiant heating. It should still work just fine for solar collectors. Just be careful of the paint you use as you are asking a lot of it.

Bill

Dave Yates (PAH)

paint

I had used high temp stove paint. I was also installing a lot of coal and wood boilers back then (much stronger back). Eshland had provided lots of touch-up paint.

The one I'd built was tailored to a large pane of thick glass I had lying around. Not sure what kind of glass works best? Wondering if coke tin would be suitable behind the fins to bounce rays back - bent like gutter or simply laid flat?

Seems like fin-tube ought to be positioned slightly off alingment given that a direct alingment (although brief for stationary panels) would defeat the ability to gain much.

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lchmb

for a pool

I have a metal roof on the back of my garage. I took a 500 foot role of black plastic water pipe and laid it in loop's on the roof and secured it in place. I then ran it back to a tee with a shutoff on the return side of the pump and walla..:) brought the pool temp up 10 degree's in 2 day's and had to shut it off during the warmer month's..

bill clinton_3

glass

Why don't you look around for some used patio glass sliding doors. Should be dirt cheap and the glass is tempered.

Mark Eatherton1

Been there, done that...

Funny how our minds work alike eh... Mine too was based on finned tube painted black and suspended in a box covered with glass. Mine too was based on thermosiphon operation, and as far as I could tell KICKED BUTT. On some days, it would generate STEAM. Impressed the heck out of me...

In reality, there are only so many btu's per square foot per day available to a given surface. As I later found out, my design was actually pretty inefficient.

I can tell you some things to NOT do.

1. Do not cover the painted surfaces until they have had a chance to out gas, or they will out gas onto the inaccessible side of the glazing...and substantially affect the transmission of the solar energy.

2. Do not use styrofoam as your primary insulation. Under stagnation conditions (350 deg F) it TOO will outgas and make depositions onto your glazing, AND as an added bonus, will shrink considerably and get hard as a rock!

3. Do not use wood as your collector frame unless you are willing to replace it every few years.

4. Do not use untempered glass as your glazing.

5. Do not use standard glass as your glazing. (Use low iron content glass instead)

6. Do not use thermosiphon as your means of circulation.

7. Do NOT under ANY circumstances put shut off valves in that will isolate the solar collectors during stagnation periods. (Don't ask me how I know this...)

All in all, I'd personally leave the collector manufacturing business up to the pro's. It's OKay to experiment with the Boy Scouts and let them discover the power of the sun, but for all practiable purposes, go with a proven manufacturer.

And what ever you do, don't get burned by the sun...it HURTS!!

ME

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Paul Pollets

Building the box...

wish I had the time to experiment...try www.thermomax.com for the best solar stuff. Prices are reasonable and the vacuum tube panels are far more efficient than flat panel collectors. Think of all the time you'd save!! Their controller (smt400) is the cat's meow.

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Mark Eatherton1

What Paul said ,plus...

Put a reflector behind the panel to re-reflect the energy that passes through the array back towards the absorbers, and put a reflective field at the base of the array to increase the "albedo" to the absorbers. Nature does it for you in the Winter, why not do it for yourself during the rest of the season. It IS free energy after all...

ME

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Kevin_in_Denver

cheap but good collectors

Monitor the classified ads for used collectors. They'll have the correct glass, insulation, and absorber plates (Lo E black chrome plating).

The homes you drive by with collectors on the roof probably don't have a system that functions. Ring the doorbell and offer to remove the system for free. A true win-win! Once you get the equipment you need, you could generate business repairing those old systems.

Mark Eatherton1

Cheap collectors in Denver...

are available from my friend Mark (Zeke) Verbeck of Dynamic Energy Group. 303-871-0747

He has other used components (drain back tanks, S.S. tanks, controls, pumps etc) as well.

Tell Zeke Mark sent you!!

ME

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