You have to keep in mind VOLTAGE also. A wall outlet is 110v 15amp. A 300watt solar panel is around 18v and 16amp peak, unless you buy a 36v panel which is twice as large and cost twice as much. If you're trying to charge something that pulls alot of amps at 110 you need a higher voltage setup than a typical 12v camper. Off the grid houses usually use a 48v array for better efficiency when converting to AC. This however is very expensive to do. If you wanted to setup charging stations in remote areas it would be much cheaper to use a generator than solar panels. It would also be harder to meth heads to steal.