DigitalDreams wrote:Just out of curiosity what type of absorbers are you using closed loop - trickle down or the newer vacuum absorber tubes.
My plan was closed loop finned aluminum absorber pipe or else copper absorber with finned heat sink
design. And transfer to two linked 265 gallon super insulated steel tanks as thats what I have laying
But am open to suggestion on the absorbers as I have equipment to create most anything metal.
Thanks for the formula, does this btu gain your showing keep the place warm most all night with out backup heat or do you supplement
existing heat source with that heat.
The Solar Shed system that is mentioned above is my system.
The collectors on the Solar Shed use premade absorber plates from a company that makes collectors. I did the glazed housing they fit into.
On my last system I did build the whole collector, and if I were doing the Solar Shed over, I'd use the new homebuilt collectors.
The new collector uses copper riser tubes with aluminum heat collection fins. The real key on this kind of system is getting a good thermal bond between the fin and the tube, and I spent a lot of time getting this right. The collectors and testing on them is described in gory detail here:
http://www.builditsolar.com/Experimenta ... lumCol.htm
Basically, the testing I did shows that the homemade collector at $5 per sqft delivers nearly the same thermal performance as a $30 per sqft commercial collector with a black painted (non-selective) absorber.
The actual solar water heating system I use (which uses the PEX version of the collector) is described here:
http://www.builditsolar.com/Experimenta ... erview.htm
At the current prices of copper, I think copper is the way to go, but the link does show how the rest of the system fits together. It has kind of a clever (cheap) heat exchanger for domestic hot water that allows the storage tank to be a simple (non-pressurized) EPDM lined box (like the Solar shed tank).
Another collector design that I think is good is this MTD design: