> The garage door is a rather complex place to put them as their are a huge range of styles and you would need to either fit the opening and replace the mechanism, or design a door for each existing type sold. On top of that wiring up solar to your house is the tricky part not putting something on a roof.

I think to be practical you'd need a manufacturing line that could build variable sized doors. Since I'm a software engineer and not a manufacturing engineer I don't know if that's economically feasible or not.