They are expensive if you don't build the grid to transfer the power to where it is needed. Then if some part of the country has a lot more than the other part you get to stop the renewables in one part and run Gas and Coal Power in the other to make up for. So younger to pay it twice.
You know, exactly how the CXU fucked it up in Germany.

In 2024 not it did cost 554 Mio€ for powering down solar and wind, while they were usable.
Meanwhile in Bavaria the CSU is sabotaging the creation oft Wind power for example. In 2023 they stated they want to build 1000 new wind power plants. In 3 years they managed 30. In BW, which is half as big, it was 2024 27. That same year 154 plants went online in NRW.
Yeah, we need a better grid. But it would help if more renewable sources would be build every where. That would also reduce the cost.