Only households can access the free electricity window. If you're not on a free plan you can get reduced rates during the solar peak window but business accounts aren't allowed to access those either.
Workplaces (and other locations) could offer free/reduced-cost charging, with the caveat that V2L is required. They could guarantee that the vehicle will be at a certain charge level at a designated time, and that the vehicle will never go below a threshold (in case an unanticipated trip is required).