I was scrolling through a bunch of car part shops websites for a high power solar panel (or two) and a good inverter. When I thought " What would Ben Heck do?" , so I was wondering if you go design and build a briefcase/suitcase which has 2 high power but cheap solar panels, a good inverter and a lead acid battery (as I have a lot of them laying around) inside and when you open it up it activates the inverter which in your case would give out (if I am correct as I am from the UK) 110v. Me and my friend have to take cordless hammer drills with us to work on a construction site but we (and our workmates) have no why of charging them. It'll help us if you can show us your approach as ours just didn't work.