According to Old_boat :

"louie" wrote in message
oups.com...
Probably the initial $$$ of the panels and other equipment necessary
for it. At least this is what puts most people off when thinking about
solar power. The solar hot water is much easier to build panels for I
think, almost to the point of being within the realm of a DIY project
for a really well-informed and ambitious person.

When I was in college I made a solar water heater for the trailer I was
living in. It consisted of a 4 x 8 box with insulated sides and clear
plastic on the top. Inside was 500 feet of 1/2" black plastic hose. It was
plumbed into the bottom of the water tank and worked with no power as a
thermosiphon. Even on cloudy days we got 170 degree water out of it. Plenty
for the three of us. However when it got a kink in it one day, I came home
to a leaking box and a blob of melted plastic. Never underestimate the power
of the sun!

According to one article I read, simple solar panels like this capable
of up to 400F, so, some care is needed in design to avoid blowouts or
meltdowns. Ie: pressure relief valves.

I've seen a design which consists of a similar box.
The innards consists of two 3/4" headers, one at either end, with 6 or so
3/8" lines running between the headers. The plumbing is all copper,
is soldered to thin copper sheet, and the whole thing painted black
and inserted in the box. Kept the costs down by silver soldering
the copper instead of using fittings. Cover is preferentially glass.
Various slight improvements, ie: a fiberglass or rockwool insulation
batt under the copper, thermopane glass, etc.

Parts cost around $100-150 per unit (cheaper than 500' of 1/2" PVC ;-)].

There are also at least two different manufacturers of an inexpensive
solar unit - mainly used for pools. 2x8 panels made from recycled
auto tire rubber with the water lines molded into it. If I recall
correctly, $100-150 or so each.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.