Power companies purchase power from all manner of sources and resell it delivered over that infrastructure. It is totally conceivable a power company would have no generation capacity of it's own.

Why should there be a supercharge if the generation capacity is also a homeowner, an end user. After all, the power company is purchasing the power one place and selling it at a profit to someone else with no capital investment except the infrastructure.

They will be selling it at a price which would factor in their investment, or someone's investment, in production capacity plus the cost of the delivery system. It would seem to be a high profit-margin item.