Solar is now bigger than coal in China — and yet still way behind

China now has more solar power capacity than coal capacity, a milestone that sounds like a turning point for clean energy. But capacity only measures the maximum a power plant could produce, not what it actually generates. Coal plants in China run at about 50% of their potential output on average, while solar panels there run at only about 14%, since they only work in daylight and depend on weather. So coal still produces far more actual electricity than solar does. In fact, China's solar fleet would need to be roughly 3.5 times bigger than its coal fleet just to match coal's output.

Part of the gap comes from China building solar and wind faster than its grid can handle. The country lacks enough power lines and batteries to move and store all the renewable energy it's producing, so a lot of it goes unused. In the first half of this year, China had to waste more than a quarter of its wind and solar power — an amount of electricity bigger than the UK uses in an entire year.

For homeowners, this isn't really about your own house or rebates. It's more a reminder that even fast-growing solar power runs into limits without enough storage and transmission to back it up — a challenge that shows up everywhere solar and wind scale quickly, including in the U.S., where battery storage is also being built out to help absorb more renewable power.