Posted by nicksanspam on January 2, 2006, 12:13 pm
Mike Pelletier has an interesting idea:
IIRC, ABC sells thin dark green galvalume barn roofing for 30 cents/ft^2.
If it's collecting hot water and the house also needs heat, it could be
more efficient with some house air flowing between absorber and glazing:
if 225 Btu/h-ft^2 of sun enters that space and it's 20 F outdoors with 120 F
water, R1 glazing would lose 100 Btu/h, so we might collect 125 Btu/h. If
2 cfm of house air flows into the bottom at 70 F and out at 120 F and the
average temp near the glazing is 95, we might only lose (95-20)/1ft^2/R1
= 75, collecting 150 Btu/h, or more, if the 70 F air stays near the glazing
and the 120 F air stays near the absorber.
Posted by SJC on January 2, 2006, 2:00 pm
I like the idea of air collectors. I have a patio cover that could take air
from the house under the corrugated material and return it on the top facing
the sun. Top the material with some multiwall polycarbonate and you have
a pretty cheap solar collector for maybe $00 per 4' x 8' section.
Posted by Drums on January 2, 2006, 7:23 pm
This gives me a though. I could use 2 collectors for hot water and 2 for
air for heating and keep the systems
Posted by SJC on January 2, 2006, 8:44 pm
Or, just combine them. Run some tubes with clamps along the corrugated.
It depends on thermal resistance and insulation, but it might work.