42 watts seems ok for a very small installation, right? I'm thinking enough to charge a phone and maybe a laptop. And, that would be driveable with a small 12V battery and a small solar panel.
You could charge a phone, but even my small laptop chargers are over 60W. The big ones are 90W.
Also don't try this in your house! pushing 3.5A through that little pinner wire it could get hot and start a fire.
But i forgot about the resistance from the load back to the source so above where I said 6m should actually be 3m. Or if two wires are parallel both from source to load and load back to source then we're back to 6m.