I worked on my solars today. I am just using them for the spa now but
they work well when they work.
I had a tree screwing with me and when I got that trimmed and turned
them on I had a leak. I guess these collectors don't owe me anything
because I got them in 2004 used from a guy who had them up 5 months
(until the roof started leaking)
Long story short I bought 8. Installed 6. Charley ate 1 of them pretty
much right after I installed them. I have 4 installed now. (different
location) One went bad a while ago and I swapped it out with a spare.
The spares were just stored out back under a tree with weeds growing
in them and such.
I assumed they must be junk.
I was thinking I would just buy all new and chuck them all.

Funny thing, just on a lark I pulled out the 2 from the weeds and
tested them with 10PSI air then water.
It turns out, buried in the weeds seems to be better for them than on
the roof because they were fine. I just swapped out the bad one and
brought the spa water from 65 degrees to 77 in a few hours. I am back!

I still plan on getting new ones but not right away. I may go with
glazed collectors.

OTOH I also have a 330k BTU propane pool heater I never use. I am
thinking about hooking that up to the spa. I should be able to put 40
degrees in the water in less than 20 minutes with that ;-)