Tomorrow morning it'll happen – the moon will pass the sun and cast a shadow across Europe. Solar power production will drop suddenly and rise quickly again. Unlike many other external circumstances affecting the grid, the solar eclipse comes with a long lead time and a very precise ETA. What we can’t predict accurately is the weather tomorrow morning and the depth of the swing. I bet that quite a few network operators would wish for a cloudy Friday morning, as it would significantly smoothen the impact of the eclipse.