400 miles of driving a month in my EV van which gets on average 1.7 miles/kwh is around 235.3 kwh.

At local rates that $16.47 in electricity (235.3 x $0.07). On average my electric bill went up 15-25 dollars a month.

I spent the first two years of ownership charging mostly from the 110v socket outside the house because over night its enough to cover my commute of around 27 miles at the time.

Now that I have a 60A 240v circuit setup outside and a 40A EVSE I never even worry about what state of charge I get home with.