Tesla has switched on the world’s biggest lithium ion battery in Australia, meeting a promise by founder Elon Musk to build it within 100 days. The billionaire inventor offered earlier this year to ensure the battery, which is connected to a wind farm, is built within 100 days or give it to the South Australia state government for free. “South Australia is now leading the world in dispatchable renewable energy, delivered to homes and businesses 24/7,” South Australia Premier Jay Weatherill said as the battery began dispatching power into the state power grid Friday. Tesla built the system to help ease energy shortages in South Australia and the launch Friday coincided with the beginning of summer in the Southern Hemisphere. The 129-megawatt-hour battery, located in the rural town of Jamestown north of Adelaide, can provide electricity for more than 30,000 homes and can also boost supply during peak demand periods. The battery stores energy generated by the neighboring Hornsdale Wind Farm, owned by French renewable company Neoen, which partnered with Tesla to build the battery. The battery farm is expected to help tackle power shortages in the summer when Australia experiences its highest energy usage. South Australia has faced a series of blackouts in recent years from extreme hot weather and storms, raising questions about its energy security. Tesla said it was hopeful the project could be a model for future ventures in renewable energy. Australia still relies on coal for nearly two-thirds of its electricity and the debate to expand into renewable energy has become politically charged. Supporters of the new lithium battery say it will help stabilize the energy grid in South Australia, which uses a high percentage of wind and solar energy, while opponents see it as more of a Hollywood gimmick than a real solution. The cost of the battery has not been made public.