51
On May 1, Germany ran almost entirely on renewables energy during the day
(transparency.entsoe.eu)
Some fossil-fuel-burning power plants were kept on at minimum operating levels (they're likely not designed for daily restarts) but provided less power than was used to pump water uphill in hydoelectric storage facilities.
And from French nuclear power outside of the solar peak:
Sorry about the graph in French, it comes from RTE, the electricity distribution network here. This is a graph of the import/export. Orange is Germany, the thick white horizontal bar is the zero: things below are exports from France and above are imports. During midday we typically import below-zero euros surplus electricity from Germany and re-export at around 100€/MWh outside of their production peak.
It is not a simple situation and it does not lend itself to simplistic judgement. There is some criticism here in France that German's surplus and inability to absorb it makes it unprofitable to develop solar power locally. The manager of RTE already warned that in the current conditions, adding renewables to our grid may prove counter-productive. We are at about 30% solar during peak hours and 12% wind.
We have reached the point in France + Germany and probably Spain where renewables are at saturation until we find better ways to handle the intermittence. This is a good problem to have, but one that was warned against years ago.
We have so some pumping into the dams but that's a very limited capability.
In the beginning of the year the German grid operators had requests for over 226GW of grid connections for utility scale batteries. That is the very first step of developing a utility scale battery site, so most of that probably is not going to be built. Then again peak load in Germany was also only a bit over 75GW.
For what it is worth, utility-scale batteries have been the next step in added storage capacity after pumped hydroelectric is built out