I paid $80 for a heated waterer and my hens ignored it all winter
Bought one of those heated waterers back in November because I was sure the girls would freeze without it. Wired it up in the run, checked it every morning, and they would not go near the thing. Turns out my old rubber bowl on the south side of the coop never froze once, even on the night we hit 9 degrees here in Ames. I ended up with a $80 plastic brick taking up space and a cord I had to keep tripping over. If your setup gets decent sun, you might not need one at all. Has anyone found a heated waterer their flock actually uses, or am I chasing something that does not exist?
Nine degrees and a rubber bowl didn't freeze? That's less about the sun and more about the water staying moving or the bowl sitting on something warm. A lot of folks find their birds just don't like the taste of water from certain plastics, so they skip it even when it's the only thing around.