If you have similar statistics for power output, could be different story.
Average car has more and more power , since average travel speed is lower and lower.
As for today feed in price for your hard earned electricity delivered by your on the roof solar panel dropped to 8 cents per kwh, when sold to the grid.
It makes much more sense to recharge own EV.
Cost of 1 kwh we could calculate at 3 cents now and will drop even further.
Petrol is likely to cost more and more.
If you do charge your own EV from own solar panel then imposing tax also will be impossible
