That's what I use and it works very well, but I would not run it off solar unless I had a robust system that would never run out of power(adequate collector and storage).we had considered an aquarium heater plugged into a solar panel power source
Might be a good time to add an outdoor outlet.....or get 2 identical waterers that you can swap out at needed intervals. That's what I did the first winter, kept one inside near the furnace to thaw and one outside in the coop.
Here's how to add your general geographical location to your profile.Being in New England
It's easy to do, and then it's always there!