Solar "Tractor" and Other Vehicles

Here are some videos of a retired engineer who has built his own solar vehicles. The current technology can't compete with fossil fuels, but little carts such as these would beat doing the work totally by hand. I would hope he designed them to be plugged-in as well, for cloudy days.






This electric tractor seems like it might be able to do more work:

http://www.renewables.com/Permaculture/ElectricTractor.htm