John Keiser wrote:
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.

Replacing the anode appropriately will help avoid that.