Based on my experience, any Blink cameras that are mounted where they will get direct sunlight tend to overheat. It would seem that the camera would have to be mounted in an area that is shaded, and connected to the solar panel, which would be in the sun. I wouldn’t want another device mounted to my home and a wire leading to the camera. In my opinion, that would not look appealing and would also make the camera more obvious.
I have the Blink XT system since April with 3 cameras, and so far they are all running on the original batteries. So battery replacement does not seem to be an issue.
I think the solar panel idea tries to fix a problem that doesn’t exist, and could potentially create new problems.
What would be nice is if the battery level indicator would show the battery level, rather than just “OK”.