They should be good for 20 years and more, with some loss of output. I have 2 very old 1 watt panels, one of which is nearly dead, the other still delivering about 500 mW. I got them used in the early 80s and they were old then!
The one that still works is permanently connected to the generator starting battery in the stick house. Haven't had to connect a battery charger in 2 years.
As for the controller, as said it could be anywhere. The bonehead tech that connected mine put it under a drawer that was under the stove, where for some reason the converter was from the OEM -- 25 feet from the batteries! :S
At 20 amps I have a full volt drop between it and the batteries! :(