In an effort to reduce the reliance on fossil fuels, Tesla and Southern California Edison have unveiled a massive battery storage facility at the utility's Mira Loma substation in Ontario, California.

The project—which is being described as the largest lithium-ion battery storage project in the world—consists of 396 stacks of Tesla Powerpack units spread across 1.5 acres. The batteries can store up to 80 megawatt hours, or enough energy to power 15,000 homes for four hours.

"This project is part of our vision at Southern California Edison to take advantage of the wind and the sun, and operate a flexible grid that delivers clean energy to power our homes, our businesses and our vehicles," Kevin Payne, CEO of Southern California Edison, said at a ribbon-cutting event Monday.

"Standing here today among these Tesla Powerpacks is a great reminder of how fast technology is changing the electric power industry and the opportunities that will come with it."

Mira Loma Battery Storage Project ribbon cutting. From L-R, State Sen. Henry Stern , CPUC President Michael Picker, Tom Doughty of CAISO, SCE CEO Kevin Payne and JB Straubel, Tesla chief technical officer. Southern California Edison

While the project officially switched online on Monday it began operating in December.

"We are very excited to bring this site online," said Tesla's chief technical officer JB Straubel. "Storage is quite a new thing … and this is a different breed of battery. This is the tip of the iceberg of how much storage we'll see on the grid."

The batteries charge up when there is more renewable energy than demand, ultimately allowing customers to use clean energy during peak hours.

As the New York Times explained, California has a need for batteries to store surplus renewable energy:

"California is on track to have an overabundance of energy during the day, when its many solar panels are producing energy, but that supply drops sharply as the sun sets, precisely when demand rises, with residents heading home to use appliances and, increasingly, to charge cars.

"The state's aging nuclear plants have been closed or are being phased out, putting even more pressure on utilities to find other ways to feed the grid. Storage is a natural solution, utility executives say, helping to smooth variations in the power flow from rooftop customers and when solar falls off and conventional plants have not yet filled the gap."

Tesla CEO Elon Musk was not at the ribbon-cutting ceremony but he retweeted a company tweet in support of the project. In the clip below, Tesla touts that its new facility, which only took 94 days to install, reduces the reliance on gas speaker plants, prevents electricity shortages, provides energy secure and reduces greenhouse gases:

Tesla and Southern California Edison agreed on the project in September following orders from the California Public Utilities Commission (CPUC). The regulators sought to expedite the use of energy storage connected to the grid to mitigate the disastrous Aliso Canyon natural gas leak, which thrust an estimated 96,000 metric tons of potent methane into the atmosphere for four months beginning in October 2015. The leak also forced thousands of residents in the nearby Porter Ranch community from their homes.

"This was unprecedented fast action on the part of the CPUC," said Michael Picker, the commission's president. "And we are once again stunned by the battery industry to meet our needs. This is another example of progress."

It is unclear how much the Tesla-Edison installation cost, as lithium batteries can be pricey. However, as Fortune pointed out, "until recently, battery storage has been a far more expensive means of meeting demand surges than natural gas 'peaker' plants. However a rapid fall in lithium ion battery prices over the past two years—driven by the proliferation of electric cars—has made the technology far more viable."

Tesla and Southern California Edison are not the only energy storage facilities being rolled out. According to the Los Angeles Times, San Diego Gas & Electric and AES Energy Storage as well as Greensmith Energy Partners and AltaGas are installing other large battery installations.

"In all, the projects are adding 77.5 megawatts of energy storage to the state's electricity grid," the Los Angeles Times reported.

California is vigorously pursuing clean energy projects to combat climate change. The state has a target of producing 50 percent of its electricity from renewable energy sources by 2030 and aims to reduce greenhouse gas emissions to 80 percent below 1990 levels by 2050.

"Energy storage projects like this one play a role in California's clean energy future," Payne said. "They are also part of our mission to safely deliver reliable, affordable and clean energy to our customers."

Tesla has plans to revolutionize the energy grid. One reason it combined with sister company SolarCity was to create a one-stop shop for electric vehicles, rooftop solar and energy storage.

Musk said in a May 2015 interview that he wants to "fundamentally change the way the world uses energy" and "the goal is complete transformation of the entire energy infrastructure of the world."