I would expect power companies to be extremely responsive to costs.

Power company cooperatives run the largest storage systems on the planet already, they built pumped storage because it was win-win for their cost structures (they use them to more efficiently operate baseload generators).

They also do things like run around buying old appliances to get green credits (a response to a negative cost imposed by regulators).

As far as selling power to the grid, the price should be fair for everyone, not just a big reward for having the upfront capital to install solar. Especially as the need to spur investment in solar tech goes away (because in more and more areas it is already cost competitive and an easy choice).