I looked into wind power a great bit. It's not feasible for this application unless you plan in being at very windy locations. I hate wind, so there's no way I'm chasing it!
We just put together a small chunk of our solar system. We have 460 watts of solar panels, one 30A PWM controller, and 1 deep cycle battery. I believe that if you had 400w and two batteries in a sunny place you'd be able to swing it.
Right now it takes our panels about three or four hours to mostly charge our battery. That's all the sun we get here. If we had 2 or 3 batteries and more sun, they'd be able to charge no problem. Our 120v mini fridge can run for a couple hours on that, but usually we run the fridge for a while during the day and then leave it off. If you don't open the door much that food will stay cold. If you have enough battery power to let it run all the time, it will take much less energy because all the food will maintain that constant temp and the compressor won't run as much.
My build thread:http://www.skoolie.net/forums/f11/build-thread-for-haulin-oats-and-goats-11237.html#post113500
A gal, a guy, three cats, two dogs, one rabbit, and one goat, traveling the country together.