What's your take on this rig ?

Black paint absorbs heat well, it does not release very well this stuff works the best.

Thermalox Solar Collector Coating is a Silicone based heat-resistant selective paint designed for use on metal surfaces of solar collector panels - will withstand up to 1000° F. Thurmalox will function with maximum efficiency (absorptivity .96, emissivity .52) when applied 0.5 mils thick. Coverage 25 sq. ft. the coating resists out-gassing (a major cause of internal fogging of collector covers) up to 400° F. Made with heat stable pigments, the coating will withstand repeated thermal cyclings and temperatures as high as 1000° F. Thermalox is unaffected by humidity, and will not peel or discolor. 13 oz. aerosol can. primer not necessary for copper or aluminum.

Probably work better for you Boston Baked, we're farther from the sun/equater here in Newburyport.

It's 19 bucks a can and one can will do if you only spray only one side exposed to the sun. You can get it here at Solar Componets Corp. They are out of Manchester NH.

I think flat black rustoleum is what.....$5.25 a can for the big ones. Krylon flat black is cheaper. Specialty paint is putting the horse before the wagon in my opinion. Black is black. I doubt you will EVER be able to measure the additional heat transfer gain and be able to attribute it to the specialty paint. In low tech solar air collectors like this you're looking for color more than performance from your paint. The heat is being transferred to the INSIDE of the can where it is being released by the aluminun. It's not relevant whether the paint releases heat or not. Hi-temp stove paints have a larger molecule which can retain heat and insulate more than non-specific flat black paint. (the reason why aircooled engines and parts are NOT to be painted with high temp paint) You would have to have laboratory conditions to measure the difference. Is it worth the expense? Prolly not.

I'm looking at these enormous Arizona Ice Tea cans, the big suckers. I think I'd try to get some of those for a collector. Or maybe some some Fosters oil cans or the like. More surface area per individual unit and fewer bottle necks might help efficiency a little. Probably more than specialty paint.

Most important for me to consider would be the adhesion properties of the paint . Obviously this is also dependent upon the surface prep.

orangecrushcj7 said:

Ductape said:

What does he use to hold the cans together?

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High temp silicone is expensive. Regular silicone caulking is a fraction of the cost, and labeled to be good up to 400 degrees. However, would it not insulate each can from one another? This may or may not be desirable. Do you really need to adhere them together? I wonder if just stacking them one on top of another, and securing the top and bottom can in each "tube" would be sufficient. That would allow all the cans to work together as one mass of aluminum, instead of isolating each can.

He should have painted the whole thing black... every little bit helps

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I would think that it is not the heat transfer from can to can that is important here, but that each can transfers heat to the air passing thru it.