Used solar thermal collectors

[huntedheads]

Hello all!

I just looked at two solar thermal collectors and need some advice. They are 4' x 10' aluminum framed and covered with what the guy calls solar glass? It's smooth on the sun side and looks to be diamond cut on the inside. They have not been installed as he bought them for the glass to build a air heater and has since changed his mind, I can get the pair plus a third glass for $400.00 total. The glass is worth more than that! I can't pressure test them at least easily as the fittings are missing but looking into the 1" pipe look very good! I have never run across a used panel and want to know what you think. And no there is not name tag I can find on them.

[huntedheads]

Only Pic I have! Sorry

[GaryGary]

Hi,

That seems like a good deal to me.

Retail on one 4X10 collector is around $1000 plus $100+ shipping.

Solar glass on collectors just means a higher transmission than regular glass (low iron content), and it will be tempered -- all good.

It would be nice if you could pressure test them, but if they look good, I would take the chance.  They probably don't leak, but if you find that they do, the glass can be removed, and a leak or two can be repaired.  One way you could get a rough idea is to tilt them up some, put a plug in the low end, and fill from the other end with a bucket -- if they have a bad leak it will show up right away.

Some advice on used collectors here:

http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm#Maintenance

Gary

[huntedheads]

That was an idea but it was 7 degrees last night and the water idea is probably not so good this time of year. We did cover one end and blow into the other for what it's worth seemed to build pressure. As soon as I convince the wife I'm going to go pick them up.?  

[scottsAI]

Huntedheads,

Not to burst your bubble, but the designs at www.builditsolar.com

Cost $4/sqft.

New build 4x10 would cost $160, two $320 building new is less than these old panels.

Just my two cents worth.

Have fun,

Scott.

[Ungrounded Lightning Rod]

It's a good deal or not depending on how much value he puts on his time.

If he has to take time out from some money-making venture (or chew up even more precious vacation time) to build the homebrew panels, their cost goes up drastically.

If he's unemployed, retired, etc. it may make sense to save a few hundred by building his own rather than purchasing and installing these pre-engineered, pre-manufactured panels.

[scottsAI]

Good point, yet they looked old in need of lots of TLC.

About the same time? Often building new is easier than restoring.

Must take apart, clean / fix then put back together!

Have fun,

Scott.

[Ungrounded Lightning Rod]

I'm not the one to ask about relative strengths of different magnet material.  I'd have to look 'em up just like you would.  (If anybody else has an answer please chime in.)

My previous post was mainly to point out that you had provided the necessary info for an intelligent answer - and to fill in as much of the answer as I could.

The one part of my answer that I'm not solid on is whether the material substitution you suggested would make enough of a field boost to be worth modifying the coil windings.  I took that claim from a previous poster.

Now that you know what info you're looking for and what to do with it you should be able to get the relative strengths of the different materials from tables available online and make your own decisions on what to do with the coils of your machine versus a reference design.

Note that it's a lot easier to figure out if you keep the material geometry the same (except for adjusting the air gap).  Things get more complicated if you change the dimensions or shape of the magnets.

[oak leaf]

Huntedheads,

I picked up two panels the same size as the ones you are looking at not long ago and spent the time to remove the glass, the frame and the rubber seal for the glass, and pressure tested the absorber.

Just solder 1" to 3/4" adapter and take two ball valves and a 3/4" nipple and a water hose adapter and fill the absorber with water and bleed the air out. Set it in the sun it will build pressure when hot. (enough to find any leaks) Then unsolder the fittings and move them to the other panel.

I found two leaks in one panel, the other panel was fine. It will be a lot easier to do on the ground than on the roof.

I also removed the absorbers and washed it down, Let it dry in the sun, then painted them with flat black grill paint. The rubber was too dirty to put back on and get a good seal so I cleaned it and all parts very well.

I went down to Home Depot and got some ultra clear window & Door Silicone II to wet seal the rubber and glass, if you tape off the parts it will look nice. I picked up some Bronze paint and Silicone for the frame, Turned out nice and took me a day and a half. If you find leaks, use silver solder it will bond well and will be solid repair.

Harlon