Quite frankly, Germany already has a lot of renewables in the mix. Why did it take so long for the effect to appear and why is it still so modest? What should be renewables share be (vs ~60% today), for complete decoupling?
Essentially it's not an isolated market, but part of a bigger whole.
As an example imagine a village that constituted 1% of the population of a country. The village was 100% renewable, and the country was 0% renewable. If the village disconnected its grid, in isolation its prices would be dictated by its renewables. But if its connected, its renewables just get traded on a market with marginal prices. If a person elsewhere in the country has more expensive generation, they'll but your cheap renewables at their price level. Thus the village will experience high prices like everyone else.
Now suppose Germany is that village in an interconnected EU market. Of course the numbers from my example are exaggerated, but the point remains: Germany's renewables aren't enough, if pricing is set at a much larger market, with fewer renewables.
Today about 20% of Germany's electricity was exported. While only about 6% of its demand came from gas. In other words if Germany was disconnected, it'd have needed no gas, and thus prices would've been lower.
Of course disconnecting isn't a good idea for other reasons, as on other days Germany imports. And Germany's ability to export its renewable excess generates significant revenues, creates incentives to build more renewables, and offsets emissions and pollution in other countries, too.
But long story short, it'll take more for one part of the whole to go renewable. As the EU is generally transitioning towards renewables we see a decoupling happen.
You need quarter-hours where renewables set the price for power. That's only happening now that renewables have reached sufficient penetration of the market.
And it will get more as batteries come online.
In a commodity market, the price is always set by the most expensive producer that is still able to sell. That's natural - why would I sell my apples cheaper than the other farmer if you need so many apples that you have to by from both of us?
... because you may have signed a longer term contract that might in turn guarantee offtake from you rather than the other farmer?
This marginal price is only for the spot market right? So the key question is more what % of the mix is spot vs longer term. And thus what the overall impact is on total blended price.
