California leads the nation in the production of solar power. Solar produces nearly 14% of the state’s electricity annually. Some months that percentage climbs higher and some months it is lower. And those high months are starting to cause problems for the Golden State.

In March 2017, solar energy accounted for 40% of the state’s electricity. Sounds great, right? It’s exactly the direction you’d expect a state so heavily invested in solar would be thrilled to experience. Except it hasn’t turned out so great.

More Solar Than The Grid Can Handle

As the LA Times reported, the state’s electrical grid can’t handle all that solar power so California actually had to pay other states to take the surplus! This has already happened several times this year. California can’t risk overloading its’ power lines and causing power outages. To prevent that from happening, the state has to offload the excess and/or order solar plants to reduce their production at certain times of year. If states can use the solar electricity, they get it for free. If they don’t necessarily need it, California might pay them to take it.

Grids Are Slow To Adapt To Renewables

The situation highlights an unanticipated problem with the power grid: grids aren’t ready to handle the influx of renewable energy sources. Since solar supply (and demand) fluctuates throughout the year, the gaps must be filled with electricity from fossil fuels. That means power grids have to have some overlap to accommodate both fossil fuel and solar produced electricity. For now, solar loses out. It’s simply easier to shut down a solar farm than a natural gas plant when supply exceeds demand.

Part of the problem may be that solar took off much faster than the state anticipated and policymakers and regulatory agencies are struggling to catch up. The solution likely lies in battery storage. As batteries become more efficient and affordable, the hope is that solar power can be safely stored and used when supply dips. Until then, power grids will still need to support both fossil fuel electricity and solar electricity equally, switching from one to the other as supply and demand dictate.