Elon Musk announced that Tesla was getting into the energy business in 2015 and now it’s betting that it will become increasingly important for the company. In 2020, it surpassed 3 gigawatt hours of energy storage deployments in a single year, largely due to the popularity of Megapack, its utility-scale battery product. CNBC visited PG&E’s Tesla Megapack site in Moss Landing, California and learned why energy storage systems like Tesla’s could be everywhere in a future of renewable power.