I don't think that will get you enough to really change the math. There's only so much additional space you can get with a fold out panel because once you start

I don't think that will get you enough to really change the math. There's only so much additional space you can get with a fold out panel because once you start going over the edge of the car you create clearance requirements for parking and also start taking up space that's generally assumed to be empty for adjacent cars to open doors into. If it becomes too common parking spots will have to get bigger or your roof will have to raise up above the level of 99% of adjacent car doors to avoid being a massive pain in the ass to everyone else. On top of that it's a lot of mechanisms to add for not adding much space above a roof mounted panel.