The demand for energy in South Australia, Australia’s fifth-largest state (by population), is estimated at just over 1700 megawatts per hour (MW). That demand comes from 1.76 million people, and approximately A$50 billion in business a year.

On Sunday, October 11th, solar energy met 100 percent of South Australia’s energy demand for the first time. As of just after noon on a mild, sunny day, the entire state was running on solar energy, most of it from rooftop solar installations. In fact, over 76 percent of the supply came from rooftop solar, while the state’s three large solar farms made up the remainder. There was even surplus energy being produced, which was exported to Victoria next door or sent to be stored in South Australia’s massive back-up batteries.

But even with 100% of South Australia’s energy needs covered by solar power, the gas power plants still ran; there are requirements to keep a minimum amount of the more steady generation engaged to ensure grid services are maintained, like inertia and system strength. Renewable energy leaders hope to see those gas-powered services replaced in the near future by battery storage.

In this case, the “near future” is hoped to be in the next 12 months. Currently, the Hornsdale big battery, built by Tesla and until recently the largest lithium-ion battery in the world, is testing its ability to provide those inertial services

Storage is one of the most important developments to support a worldwide switch to renewable energy like solar. Dependent on external factors like sunshine, wind, and rainfall, renewables are not able to deliver power as consistently as consumable sources, and therefore storage is needed to even out the supply between times of plenty and times of scarcity. South Australia is testing energy storage both at the massive level, like the Hornsdale battery, and at the household scale.

The next milestone South Australia hopes to meet is to have rooftop solar installations alone generate 100% of the state’s need. They anticipate that to happen sometime this summer (in Australia, summer occurs during the months of December, January, and February).

Photo via Shutterstock