Hybrid solar panel (photovoltaic and thermal)

Step 2 Building the heat exchange system

Photo 1: Soldering 1/4" (~0.5 cm) flexible copper pipe to the Aluminum backplate. The backplate is about 0.80 m x 0.65 m. I used about 7 m of pipe. Make sure you use the proper tool to bend the pipe to avoid pinching it off! The Al. plate cost about $10. The pipe about $20.

Photo 2: I thought it was impossible to solder to aluminum. Incorrect! You need the right FLUX. I bought this from McMaster-Carr for about $30. Notes: 1) buy a smaller pot, this was way more than I needed. 2) Be careful, this stuff is nasty: it has Fl and breathing its vapors or touching is NOT recommended!

Photo 3: Here my friend Martin is soldering the pipe and plate. Note that we worked outside, there was a good breeze and we used some protection!

Photo 4: End-result: will not win a soldering contest but was not bad for our first time soldering aluminum...

Photo 5: Close-up of the solder job...  Could be better, eh?

Comments

[mikesnyd]

You are right with the right solder you cna acomplish this but i think you would have been more successful with brazing the copper pipe to aluminum. Faster less fumes and no flux needed. Check this instructable out. http://www.instructables.com/id/Quick-and-easy-brazing-aluminum-copper-and-nonfer/
I really like your ideas so far. Nice instructable.

[efootprint]

Is it possible to just get an old coil from the back of an old refrigerator and use it?

[grimgroper]

 possibly... but dont release the refrigerant gass!!! 

[Shiftlock]

Perhaps you should have traced the pipe's shape onto the Al sheet, brushed the flux onto the path, then pre-melted the solder along the path.  Then you could have tinned the entire copper pipe and simply joined them together with the heat of a propane torch.  I think that would have created a continuous contact point, and made it a lot neater.  It probably would have been quicker and easier than soldering a bunch of contact points as well.

[carlos1w]

Good idea, this is one of the neat things about instructables:  you always learn something new from your "readers".  Next time I will try it the way you suggested.

[chrwei]

what about using a thermal epoxy instead?  might cost more, but it would be a lot easier to control and cover the full contact point of the pipe to the sheet

[carlos1w]

I think that epoxy would have worked pretty well (even non-thermal epoxy) given the small energy/surface area ratio.