It's high time we faced reality: each source has its own particularities and, above all, associated costs.
Costs relate to the production itself and also to the type of dispatch, whether firm or non-firm.
A generation that operates 24/7 is, in this sense, different from one that doesn't operate in this "permanent" regime.
My suggestion is very simple. Each source should have its costs allocated according to its production.
And the supplier should bear the costs related to the dispatch of other sources to compensate for when it is not "delivering."
This way, payment would be "agnostic". In other words, there would be a fairness in billing systems. And the customers would choose according to their interests and convenience.
If you'd like to explore this possibility, please contact me to discuss next steps.