We let our corn feeders run 3 seconds morning and evening year round. They only have corn in them from Sept to mid Jan. We find that the feeder motors, batteries and timers are easier to maintain running year round.
I'm on 12v systems and I do this as well, but move to a once per day 5-10 second run in the off-season. 5 years and going strong, but my solar panels are starting to visually show their age with some cracking, etc. Motors, timers, and batteries are still running strong and batteries show full charge despite solar panel conditions.
I get a squeal from time to time from the motors but a shot of Boeshield T-9 or silicone spray on the motor shaft calms the squeal nicely.