So you are suggesting there is two types of electricity markets: one for green electricity and another for say black electricity. Let's say their prices are in equilibrium.

So you increase your green electricity demand, and green power generation capacity is increased and more green electricity is made.

However the demand for black electricity hasn't decreased.

But you have created an arbitrage opportunity e.g. someone decreases their green electricity usage, and increases their black electricity usage.

Your fallacy is that you think it is possible to create two separate electricity markets (maybe separate grids, or strong regulation) for a good that is quite fungible.

For at least 10 years I have had a contract for "green energy" from my municipal supplier. They, in turn, contract to buy power from solar and wind suppliers to fulfill the consumption of those who are part of that program.

It does indeed work as I describe. And, because the wind and solar providers are among the lowest-cost providers at this point, "black" energy is losing market share quite quickly.

I understand electricity markets quite well and live and work in one of the most dynamic ones in N. America. This is how it works.