wrote:

http://www.ehow.com/how_4669902_sola...paign=yssp_art

Copper rolls come in 60' rolls which makes it easy and compact to
build a Solar Collector around. I reckon one roll would provide
enough hot water for a 40 gallon water heater in FLorida...but another
roll could always be implemented easy enough. Price on a roll of 3/4"
copper runs about $140 with maybe another $50 in misc. collector box
materials, making it awefully inexpensive . A suitable heavy duty
water pump runs about $140 ,

Many people have their solar collectors removed when they get their
roofs reshingled, so you should be able to get them cheaply or for
free from roofing companies. That's how I got the four panels at no
cost, and they were good ones made of extruded aluminum, tempered
glass, and copper tubing on aluminum extrusions. I think people toss
their solar heaters when they need a repair and are told a new pump or
tank will cost $500-$1,000, installed.

Commercial 3' x 6' collectors will have 5-6 rows of 1/2" copper
tubing. Ours have the tubing pressed into aluminum extrusions made
for solar, but others may have the tubing soldered to 6"-8" wide
strips of copper flashing (can be very thin) or a piece of galvanized
steel (not as thermally efficient but good enough). It's easier if
the tubing goes on the back because it makes painting the surfaces
easier. Black barbeque or exhaust pipe paint works fine but has to be
fully cured with heat lamps or else the glass will fog up inside.
Also you don't want the tubing or the collector plate metal to touch
the metal box at all or heat will be short-circuited to the outside.
Isolate the tubing with pieces of fiberglass cloth or insulation, and
use rubber grommets where the tubing has to pass through holes in the
box. A lot of collectors are insulated with foil-backed rigid foam
isocyanurate or urethane (styrofoam melts too easily) made into a box
(glue with silicone rubber sealer), foil facing inward.

In a mild climate like Florida, don't rule out simple recirculation
for freeze protection because it can save a lot of money by not
requiring a heat exchanger (open loop water, no closed loop
antifreeze) and allowing a much smaller, weaker pump to be used (1/100
HP, only 4-5' of head -- must open an indoor hot water faucet to get
the system primed). But have at least two freeze sensors, one for
the outlet, another for the inlet), each calibrated for 37°F, not
32°F. The pump needs a spring-loaded check valve on its outlet or
thermosiphoning will cool off the water in the tank at night. Also
this type of system can use a regular water heater. It can be used as-
is and without power connections in a 2-tank system (probably best for
gas), but for a 1-tank system the tank can be modified by
disconnecting the bottom heater and shortening the dip tube so it
extends only about 6" below the top heating element. The drain valve
now serves as both the cold inlet from the water supply and also the
outlet to the pump.