where by cheaper you mean slightly more expensive if you compare to public charging stations that are the vast minority of charged miles, and 9x more expensive than charging at home.

Last I checked it was a fair bit easier to put up 4 solar panels and an inverter than build your own oil refinery.

$1000AU worth of panels, a $200 charge and a $1500 battery will give you 30km or so a day.

Pays off in about 4 years vs $1.80/L even with very optimistic fuel economy. if you park at home then the price halves.

If you can put the panels where you park that goes down to 1-2 years.