> This doesn't explain why Germany has so high electricity prices.

It's the main thing which does.

Say you have two energy sources, Alice Electric can deliver at €0.03/kWh but only up to 10% of your demand, while Bob Energy can deliver 200% of your demand but all units will cost €0.5/kWh.

The net result of the electricity auction, as described, is that the consumers pay Alice and Bob €0.5/kWh each, which gives Alice a €0.47/kWh profit margin and therefore lot of money to expand operations if she wants to, but until she can actually supply 100% of demand, it's priced by what Bob charges.