Something doesn't sound to me quite right. If 1km2 can get you 20k L/d then 1m2 would give you 20L/d? I doubt that otherwise everyone would make their own fuel for car in small garden. Unless the actually mean 1km x 1km area.
Well yes, that’s what a square kilometre is. It’s (km)^2 not k(m^2).
20kL/km^2 means 20mL/m^2 (in american that’s a hair more than a tablespoon + a teaspoon).
There’s a lot of fudging factors like a tiny 1m2 panel vs. a massive 20m x 5m area, conversion efficiency, etc. but your point that “everyone would make their own fuel for car in small garden” isn’t that reasonable. Well, assuming they are not using gasoline.
So that one panel gets you 6-7 miles of EV range a day.
A typical house needs probably 15-20 panels to produces it’s needs (assuming you have storage) before EVs are even in the picture.
Of course most cars are not at home all day, and cloudy days have to be accounted for. So we have to assume some sort of system to get around that. (the obvious ones are battery at home to charge, or sell to the grid at home and buy from the grid where you are charging) Solving these problems is not easy, but the math works out that you can do it.
Is not what your link says, it says:
> U.S. daily travel averages 11 billion miles a day — almost 40 miles per person per day
Which is a different metric.
Perhaps more pertinent is:
> (The Average Driver) Drives 29 miles a day
Your qualification of your numbers was
> very good sunny location
not
> some random unspecified location