Volkswagen-backed Electrify America has reached an agreement to buy battery storage systems from Tesla for its growing network of electric car charging stations.

The Tesla units will allow the stations to stockpile cheaper, off-peak electricity to reduce the price for charging throughout the day. The cost of the agreement was not announced.

Electrify America plans to install them at 100 key stations this year as it also adds locations and new high-speed chargers that will be compatible with Porsche’s upcoming Taycan electric sports car, which is a direct rival for the Tesla Model S.

The Taycan will be the first vehicle compatible with the 800-volt chargers, which Porsche says can deliver up to 60 miles worth of electricity in just four minutes. That's roughly twice as fast as the current top systems.

Interest in the Taycan is so strong that Porsche has doubled production plans ahead of its launch later this year.

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