I charge the Torqeedo off the house batteries, which are charged by solar panels. The Torqeedo charges either by a 110v AC chord or a 12v chord. 100% solar charged. It does take a while, but that is not an issue. As I said, I can go days on a charge, then plug the battery in when it is convenient. I rarely run the battery down past 50%, but being lithium Ion, that isn't an issue either. No more gasoline stored in the cockpit, no more mixing oil and gas, no more oil in the water from the 2 cycle engine, no more noise. The Torqeedo is very efficient, I think. It has the same amount of power that my 3hp Mercury had.
If you get a chance, try a Torqeedo. You'll like it!