solar cells can have a decent impact on very exotic efficient designs like the aptera. On a normal sedan it is better to put the solar panel elsewhere than the car
5 megawatts) / ((1000 watts) / (square meter))) / .18 = 27 777.7778 m2
And, of course, this is only when sun is shining with max intensity and certainly not delivered at night.
Figure in the Northeast you get 4 hours times this power on a typical day, and it’s not aligned with peak charging demand.