You make an excellent point - so much so that it already exists today at the wholesale level in many markets. What you're describing is Locational Marginal Pricing (LMP) - a reasonable introduction is here: https://www.enverus.com/blog/an-intro-to-locational-marginal...

In the wholesale market the biggest consideration is transmission capacity - if I can generate 100MW of electricity at $15/MW but the transmission line between me and the demand can only carry 20MW, and another generator can generate 100MW for $30/MW with excess transmission capacity to the demand, the price at the demand will lean heavily towards the $30/MW price.

The same model could be applied to local grids as a way to "manage" residential solar installations for example; overcapacity is penalized through pricing signals (but if you throw in batteries so you can shift the release of electricity...).