I think that the plan for the batteries for the semi's
might be to use multiple 200 kWh powerpack's for batteries. If they put the infrastructure in place to swap them at supercharger sites there's a symbiotic advantage to using powerpacks.
Tesla benefits with less expensive power for the charging and by charging from powerpacks they can easily increase the charge rate. By using that system to supply semi's Tesla will be able to sell a massive amount of electricity. If they can get most of it from their own Solar panels it would be perfect (double green),
plus affordable for customers. Ecologically green and financially green
.