Rooftop solar panels are flooding California’s grid. That’s a problem.

California now has nearly 47 gigawatts of installed solar power—enough to power ~13.9 million homes and supply over a quarter of the state’s electricity. Because of abundant solar generation on sunny days (especially in spring, when demand is relatively low), there’s often more electricity than is needed. That leads to electricity prices going negative and solar output being curtailed (i.e. wasted or “thrown away”).