Apple announced Wednesday that it’s building a big battery storage project at a Northern California solar farm. But what the company did n’t share is that the battery packs will come from Tesla, the verge has learned.

The newly-announced setup was approved by the Monterey county board of supervisors in 2020. It will consist of 85 Tesla lithium-ion’megapacks’. Will be used to help power the company’s corporate headquarters in Cupertino.

The company has built bigger battery storage solutions in Australia and south of Houston, Texas of around 100mW in size. Apple touted it as’one of the largest battery projects in the country’.

Apple VP Lisa Jackson said the challenge with clean energy is that it’s by definition intermittent. If we can do it, and we can show that it works for us, it takes away the concerns about intermittency.

Apple uses lithium-ion batteries in many of its products. It’s not known to be working on any grid-scale projects.

Tesla CEO Elon Musk said in December that he tried to pitch the idea of Apple buying his company back in 2018. Apple CEO Tim Cook’refused’ to take the meeting.

Tesla is best known for its electric cars but has spent years trying to build up an energy storage business. It has gotten increasingly involved in large-scale energy storage projects like Apple’s.