Can you explain this? Do transitional winds not cover mornings (the most energy heavy time of the day) rather well?

There are times in the year, which are called "Dunkelflaute" in German and in this time you have both: No solar energy and no wind energy. This mean, in this time you have a greater demand than produce.

Another problem is that the main demand of energy (privat households) is between 5 pm O'clock and 10 pm o'clock. At this time frame, you have usually lesser solar energy, while the peak of solar energy is during the noon, when the main part of people worked.

The problem is: How to store the energy for later use?