The issue here is that EVs tend to be charged when the sun is down. When sun is up you tend to be at work or driving. The surplus power is coming from solar.
Depends. residential fleets v commercial fleets. different behaviours.
Even most residential batts that get plugged in when they get home typically have SOC >40% (depending on jurisidiction).
surely its possible to invent a "plug in road" system, then cars could charge (at least on highways etc) even when driving. I had this thought ages back when EVs first came out, to tackle the problem of long charge times when doing cross country road trips.
EVs are parked 95% of the time. If it's parked, it can be charged. Work places also have electricity.