Fixing up a free solar hot water panel

[bennelson]

Hey guys,

A while back, I got a solar hot water panel for free from my cousin. These were panels from the '70's that looked like they were never hooked up right.

He eventually CUT them off his house, and stacked them behind the garage, to eventually take in for scrap metal. I offered to take them off his hands.

I only had space to take one with me at the time. The idea was to figure out what would need to be done to fix up this panel - then eventually do that to all ten of them.

So, since my buddy Tim is also interested in DIY solar, we headed over to his house to fix this one up.

Here is a video of what we did.

-Ben

http://www.youtube.com/watch?v=gKnIhWh7yCM

[thatguitarguy]

Good work!

I have a couple of these panels I need to rehabilitate.

Tap water might be OK for experimentation, but it will start to work on coroding the interiors of the copper pipe. Those risers are pretty small and it won't take much to clog them up. If it appears there is any restriction you can just run some vinegar through the collector for awhile to dissolve it. If you want to run with water be sure to use pure distilled water. If you decide to permanently install it on the roof a better way to go is propylene glycol in a closed loop system heating the water in a separate tank. With this type of system it's important to make sure that the pump is running whenever the sun is out in order not to let the fluid stagnate in the collector, or it will overheat and become acidic which screws everything up.

[bennelson]

It probably isn't a bad idea running some vinegar through all these panels as they are fixed up.

Also, I was able to stop by a home improvement store today. They did have all copper sweat-on unions there. The nut on the union was either cast copper or bronze. The unions cost about $11 each! Not cheap, but only TWO would be needed per panel.

Each panel would get ONE-HALF of the union on the right side of the pipe, and the other half would go on the left. When all the panels are laid out side-by-side, each one will form a complete union. Just screw together, and you have a solar hot water system!

It has been the sunniest week of the late winter so far! Of course this weekend, when we can actually RUN the panel, I am sure it will be cloudy the whole time.

In our climate, these panels will need to be in a closed-loop filled with glycol. For testing, water will work great.

[Daox]

I'm very much looking forward to the weekend to try it out! As soon as I can verify that the heat won't cause any leaks, I'll get it running on a timer or something. Two temp sensors and I could have an arduino controlling things pretty easily too.

[bennelson]

I am also working on a solar hot water system for my house.

For it, I will need a tank, heat exchanger, and pump. I already have a used 4'x10' collector that I bought last summer.

As for the tank, I picked up an electric water heater I was going to modify, but the more I looked at it, the less happy I was with the corrosion and threads/connections on it.

A neighbor was throwing out a 50 gallon steel pressure tank. It is in much better condition than the water heater. I realized that the tanks themselves are both the same size, so I cut off the insulation from the water heater to wrap the pressure tank with. You can read all the details about that HERE.

I'll still need to find a pump, coil copper pipe around the outside of the pressure tank for heat exchange, and tap into my existing water system, but the project is well on its way!

[Christ]

Ben,

Are you sure you want all the panels in series, so the already heated water from one goes into another to get heated further? I'd think you'd want maybe two in series to get the temp up, but then plan the rest in parallel (groups of 2 in series piped into a manifold) to increase the heating capacity and speed of the system.

Just a thought to ponder.

[bennelson]

I would plan on connecting them all in parallel.

The panels have 1" copper pipe all the way through on BOTH the top an bottom of them.

BOTH ends of BOTH the top and bottom pipes would go from one panel to the next to the next.

That way all panels would be in PARALLEL. The incoming (cooler) fluid would go throw the lowest internal pipe to all the panels, flow up through all the the riser tubes, and move through all the upper tubes, then out to the solar storage/tranfer tank.

[Christ]

Originally Posted by bennelson

I would plan on connecting them all in parallel.

The panels have 1" copper pipe all the way through on BOTH the top an bottom of them.

BOTH ends of BOTH the top and bottom pipes would go from one panel to the next to the next.

That way all panels would be in PARALLEL. The incoming (cooler) fluid would go throw the lowest internal pipe to all the panels, flow up through all the the riser tubes, and move through all the upper tubes, then out to the solar storage/tranfer tank.

Shift key stickin'?

I see now how they work. The other type of panels I was looking at (to get context for yours) weren't designed like that, they each had one inlet and one outlet, from bottom to top, like an electrical connection.

Yours, the way they're built, are already in a parallel series, because if the water gets warm enough before it makes it to the other end of the collectors, it just moves up into the hot-flow tube. I under-fer-stand.

[bennelson]

My single large solar panel has only one lower-left input pipe and one upper right output pipe.

To hook it up to another panel in parallel, you have to add additional external piping. More work, more things to insulate, etc.

It seems like most panels now a'days have internal manifolds and are very easy to parallel up.

[bennelson]

Here's a video of me experimenting a little bit with my 4x10 solar panel, a tub of water, and a coil of copper tube submerged in that tub.

This morning, there was a half inch of ice on the the top of the tub of water, but the water temperature was 140 degrees only three hours later!

http://www.youtube.com/watch?v=JRvxHA4AQbc

I also didn't realize that the YouTube thumbnail choose the frame where I have the word "Stratification" on the screen. It's like our vocabulary word for the day!