There is no way you've ever run a semi or you'd not even bother asking the question.
Our drivers will spend 120k on diesel a year. We'll spend less than 50k on electricity, we think we can negotiate that down to about 35k doing wholesale contracts night charging (80%). Our log trucks run about 500 miles a day, close to it. Heavy loads, high fuel consumption. 5mpg is about it. We run 6 days a week. For a regular fleet driver it will vary slightly. It depends on just how cheap they can charge them up at night. I bet down to .07 or .06 here in va.
The business case is just a no brainer. It might be $60k it might be $80. Who cares. It might be $40k for something like a Pepsi truck. Who cares. It is an absolute slam dunk the fuel savings pay for the truck and electricity.