Of interest: Oregon's prisons are moving toward solar energy.
It doesn't seem an obvious fit, but it apparently can work. In this high-priced arena, significant energy costs at a few of the facilities already have been trimmed back. The Two Rivers Correctional at Umatilla has has a good enough experience with it that others are now sending out requests for bids.
One more thing in a prison system that isn't reliant on an external network. There could even be a security advantage in that.