The grid upgrade can cost millions for a DC fast charging station.
The inverter to make the DC power can cost 100,000.
Why not skip all this and have a diesel engine coupled to a 400V DC generator, thereby skipping the inverter and grid upgrade?
I think this would be cheaper, and lower capex and operational costs. Not to mention, most streets have natural gas lines which could power the diesel engines with a cheap and clean burning fuel. Natural Gas is very cheap around 4c/kwh. A 20% efficient generator, would yield 16c/kwh.
What you are describing is building individual power plants for DCFC stations. These would need engineering, land, and regular maintenance. Just because the fuel is cheaper does not mean that they are cheaper. There is a reason people don’t power houses with natural gas.