My panels have lasted 30 years [in Hawaii] but I've had to replace the
plexiglass covers and resolder a joint in the manifold.
A roof top is a harsh environment and poor quality materials will show
defects eventually.
My panels feed into a normal 80 gallon water heater for storage. The
heater is 20 years old.
Even though the thermostat is set extremely low and the elements are rarely
activated, I assume the tank will eventually rust and develop leaks.


"David Nebenzahl" wrote in message
.com...
On 7/30/2009 10:09 AM JIMMIE spake thus:

From the info I have gathered the life expectancy of a solar water
heate is comparable to a run of the mill non solar water heater. I
would think they should last just about forever. What goes out on
them?

The only thing I can think of is the panels themselves, which could fail
if exposed to freezing temperatures with water in the tubes. However,
there are heat-exchanger systems which have another fluid besides water
(propylene glycol for one) circulating through the panels which are pretty
much immune to freezing.

One piece of advice I can give is to stay far, far away from so-called
"draindown" systems if you live in a freezing climate. These systems are
supposed to drain the water in case of cold weather, but through a small
hole. If the hole clogs, then your panels could go kablooey.


--
Found--the gene that causes belief in genetic determinism