Billionaire Elon Musk defied his doubters to beat Friday’s 100-day deadline and install the world’s biggest battery in the Australian outback. He’ll probably relinquish that crown by February.

South Korea’s Hyundai Electric & Energy Systems Co. is building a 150-megawatt lithium-ion unit, 50 percent larger than Musk’s, that the company says will go live in about three months in Ulsan near the southeast coast.

With battery prices tumbling by almost half since 2014, large-scale projects are popping up around the world. Developers have announced lithium-ion battery projects with total capacity of 1,650 megawatts per hour in 2017, four times the amount for all of 2016, according to Bloomberg New Energy Finance.

Smoothing out the intermittent nature of those sources when the wind dies down and the sun stops shining has traditionally rested with natural gas “peaker” plants that can fire up to meet demand at night and in the early morning. Now with the cost of batteries falling, large projects can be deployed within three months to meet that need.

The battery-storage industry is becoming increasingly important in places like South Australia, which has less access to traditional fossil-fuel sources like coal and gas than the rest of the nation. Instead, the region gets 41 percent of its electricity from renewable energy, one of the highest penetrations of wind and solar in the world.