It sounds like the author is envisaging a system that works without power (as long as the batteries last).
The ISPs also have a system that runs without power so long as their batteries (and gensets) last. Typically 1 or 2 days without refuelling.
The ISPs also have a system that runs without power so long as their batteries (and gensets) last. Typically 1 or 2 days without refuelling.