The big issue we found working on this panel is that the frame of the panel is made from FOLDED ALUMINUM.
It's nice that it makes for a lightweight panel, and I am sure these were less expensive panels when originally purchased. The insides are all copper pipe and sheet copper absorber, so the important part is high-quality.
The problem with bent aluminum is that the sides are attached, as it's all one big sheet. If the sides of the panel were made from a separate piece, such as extruded aluminum rail, the sides could slide on OVER the pipes that have to stick out. Because of the folded frame, the original manufacturer made the copper pipes stick out on one side, and not the other. To connect the panels to each other or the intake and outtake pipes, you push a pipe INTO the inside of the panel and connect it with a rubber coupler by sticking a screwdriver through a hole in the frame to tighten a hose clamp.
Not an easy thing to do, and I am not sure I would trust it for 30 years in a closed-loop system.
After monkeying around for a while, we still couldn't figure out a really good way to solder on some pipe extensions that would still allow all the copper to fit back into the box. Our "compromise" of making this work was to more or less rebuild the rubber couplers with some short pieces of radiator hose and stainless hose clamps, install them with the copper OUTSIDE of the box, so we could really get our hands on those things and tighten them up.
The panel has two 1-inch header tubes, one on the top, and one on the bottom. Both tubes run horizontal, and are open on both ends. Typically, water (or antifreeze) would run in one end of the bottom, and the opposite bottom end would be capped off, so the water would rise up through the small tubes with the copper plate, soaking up the heat of the sun. The water comes into the top tube (which has the one end capped) and flows out the opposite end.
For a single panel system, the opposite two corners would be capped off. If you used the panel in series with an additional one or more panels, both the bottom tube and top tube would just connect straight to the next panel in the system. One of the tube ends would still be capped only on the first and last panel in the array.
We decided that this panel was only going to be used by itself, but in the future might be part of an array. If it was, it would be an end unit, so we could still permanently cap off one end.
To do that, we had to clean off black paint from one of the chopped ends so that we could solder it.
Then we installed and soldered a plain copper end cap.
I know the soldering isn't the greatest. We are both plumbing amatuers, but the soldering did get better as we continued.
On the kitty-corner from the capped end, this corner also needed to be capped, but possibly connected to another panel in the future. Rathe decide on the exact style of connector, we simply added a stub of pipe, and let it run long, so there is enough material that in the future it could be cut off with plenty of room to install whatever would be needed there.
Finally, we got to working on the ends the water would be coming and going through. There, we made new rubber couplers. We soldered up little adapters of a 1 inch to 1/2" reduced, a short piece of 1/2" pipe, and a pipe to threaded adapter. Then a brass thread to barb adapter screws into that. Finally, a high-temperature hose goes on the brass barb.
By that point, our soldering was starting to look slightly less hideous...
We also found that the radiator hose we used to make the coupler was almost exactly the right size to fill in the gap between the copper pipe and the aluminum frame.
On the output end of the panel, we made a similar adapter, this one with a male thread adapter, so it could go straight into a a brass tee. This way, we had a point for a temperature gauge to mount.
We gently washed off the collector manifold, and we were ready to reinstall the glass on the panel. The glass has a smooth side, and a side that is slightly textured, which I think is designed to diffuse the light? Does anyone know which side is supposed to be inside and why?
To mount the glass, we got some of those little plastic clips used to mount a mirror against the wall. In some holes they went right in. Other holes were too big, and the screw would just slip. I think the glass was originally installed with some sort of clip and self-tapping sheet metal screws.
The mirror clips show up pretty well in this photo.
We took the panel to the upstairs un-used bedroom. It has one window, which is just a little smaller than the panel. The idea was that we could simply mount the panel up against the window. The sun would shine on it, but it would still be in conditioned space where it couldn't freeze.
Here is the hose going to the panel inlet.
You can see that the pipe shifted just a bit. Originally, these panels had a grommet that went around between the pipe and the hole there. Four of those total held all the copper in place nicely. Our version, not as well.
The pump is a 12V DC stainless steel bilge/utility pump. Don't have to worry about it rusting and you can run it on a battery or a wall adapter. Tim didn't have a wall adapter, but he did have a old computer power supply, modified to be used for testing and running 12V and 5V electronics. At 12V, this pump pulls about 60 watts (5 amps) and really pumps faster than we need it to - something like four gallons per minute. Since DC motors run at a speed proportional to voltage, we hooked the pump up to the 5V power lead. The pump ran slower, but still running more than enough water through. At 5V, it only pulled 25 watts! So we were saving energy now too!
The bottom of the panel has a wimpy flange that sticks out. We were not about to set the full weight of the panel on that, so we added some 2x4 blocks to support the weight.
In this photo of the completed test system:
You can see:
Hose from the barrel to pump on the floor.
Computer power supply powering pump and connected to Kill-a-Watt for energy monitoring.
Hose from pump to bottom right panel water inlet.
Capped "stub" pipe on bottom left of panel.
Capped pipe on top right of panel.
Water outlet on top left of panel with temperature gauge.
Return hose from panel to barrel.
So, there you have it. In one day, rehabbing an old solar panel for only the cost of a few parts and one trip to the hardware store.
While this is NOT a permanent installation, the experience is well worth it, and we now know what we would have to do to fix up the rest of these panels.
NOTES:
There was one leak we found after filling the system. It was the inlet hose barb thread. The barb simply wasn't screwed in tight enough. Took a wrench and about 5 seconds to fix.
All of the solder joints were good. No Leaks! While our soldering was far from professional-looking, it did at least do the job! After having the panel vertical, and filled with water, I realized we had no way of checking a few of the solder joints or the rubber couplers for leaks. Perhaps the right way to do this in the future is to pressurize the manifold with it outside of the frame. That way, the whole thing can be inspected without the glass and sheet metal in the way.
The rubber couplers were covered with reflective metal tape, to prevent UV damage to the hose.