Bob F wrote:
wrote in message

I think so. A $1 foot of 1/2" copper pipe pounded into a groove in a $1 ft^2
of brown-painted aluminum roofing coil stock with a 1.5 Btu/h-F-ft^2 airfilm
conductance at 140 F in full sun in an 80 F sunspace with a $1.50 ft^2 of GE
HP92W 10 mil R1 polycarbonate glazing with 90% solar transmission can collect
225-(140-80)1.5 = 135 Btu/h, at a cost of $3.50/(135/3.41) = 8.8 cents per
peak watt, and people can sit in the sunspace, and the water heater's "waste
heat" can heat the attached house.

Care to give a little more detail of this construction? What is a "groove in
roofing coil stock" for instance?

Perhaps he means to take the flat aluminum flashing and form a U shaped
channel down the middle that is the same width as the copper pipe. The
copper pipe then can be press fitted in this channel or pounded into
this groove.

Anthony