Today a solar eclipse will sweep across Europe. Millions of people will stare at the unusual sky and the strange darkness it brings. But there’s one problem: solar power. Never before has an eclipse happened at the current level of solar power generating capacity, especially in Germany. Its 1.4 million solar energy systems account for around a quarter of the solar capacity installed on Earth, and solar provides about seven percent of the country’s electricity. What’s the impact on Germany’s electricity supply when during the eclipse solar generation goes rapidly down, albeit temporarily? We will soon know.