Tesla prepares for its future electric vehicles to suck up power and spit it back into the grid. Tesla didn't define when this capability would be ready when CEO Elon Musk published Tesla's much-anticipated Battery Day event in Palo Alto, California.

But instead of exciting this growth, Musk downplayed how helpful it would be for the company's vehicles to connect to the grid. He wants customers to buy Tesla's Powerwall batteries for their homes, instead of using its EVs as batteries on wheels. "I think it's going to be more suitable for people's freedom of action to have a Powerwall and a car," said Musk. A deficiency of infrastructure and customer buy-in for cars that can offload remaining energy to the grid could also cause Tesla to pause.

Despite Musk's reservations, there's a bunch of potential for Tesla's electric wheels to do also then drive. A fully charged Tesla Model S Long Range Plus might be capable of driving 400 miles on a single charge of its 100 kWh battery pack. Still, most drivers aren't going almost that far in a day. All of that excess energy could be better used, keeping the lights on in the driver's home when a sudden blackout. This event isn't unusual in California throughout the wildfire season. If Tesla owners can discharge their batteries to the grid whenever there's peak request, they might even be able to limit power outages and make some money in the process.

"The volume of energy storage you have driving on four wheels is significantly more than any electric service will build and put on the grid," says Gerbrand Ceder, a professor of materials science and engineering at the University of California, Berkeley. "So it now begins to make sense that you use this as a means to stabilize the grid."

A decade ago, it might not be worth it for a Tesla owner to earn by selling money to the grid because it decreased the battery's life. Former Tesla CTO JB Straubel has remained a skeptic for that reason. Ceder used to be a skeptic, too, but he's not anymore. According to Ceder, batteries are not enough to give energy back to the grid without losing much battery capability in the process. "Now you're purely making money doing vehicle-to-grid," he says.

Still, many foundations need to be built so that electric vehicles can give back to owners' homes and the grid. For starters, Tesla will require to make new connected chargers, and families would need additional hardware to take in power from an EV battery.

During Battery Day, Musk's remarks imply that the company doesn't believe its consumers are hungry enough for vehicle-to-grid abilities yet. "Very few people would use vehicle-to-grid," Musk said during Battery Day. "We had that with the original Roadster. We had vehicle-to-grid capacities — nobody used it."

The theory is that Tesla owners buy the car to drive it, not to use it as a battery. "It's very doubtful if your car, rather of being charged, it discharged into the house," Musk said.

Drew Baglino, senior vice president of Powertrain and Energy Engineering at Tesla, suggested that its Powerwalls might be a better sell to services than its electric wheels. "Recognize that your car isn't plugged in 24-7, so it's an irregular resource for the grid. It'll have a price, but it's not the same as a fixed battery pack," he said yesterday.

Vehicle-to-grid abilities could ultimately set Tesla up to become a vital energy arbiter, says Ceder. Tesla's become the most prominent electric automaker globally; it arrived a milestone this year when it delivered more than 1 million cars globally. Collectively, its global fleet can operate as a vast virtual power plant.

Though Tesla is already trying to do something comparable with its Powerwalls, according to an April report, Tesla's pilot domestic virtual power plant in Australia has received positive feedback after saving residents up to 20 percent on their energy bills. The company set up solar and storage systems in 1,000 plus public housing properties, and it plans to expand to 50,000 more homes.

"I think many of us have anticipated Tesla to become a player in electricity arbitrage because that's what they've established themselves up for," Ceder says. "I always jest that Tesla was not a carmaker; it was a battery pack creator."

Tesla's decision comes as more intense wildfire seasons make extensive blackouts more general across California, where Tesla is headquartered. "Right now, there's a genuine requirement for providing backup power that batteries can give," says Jeff Cook, renewable energy policy and market analyst at National Renewable Energy Laboratory.

If Tesla doesn't satisfy the need first, others might. Nissan and Honda have both attempted into bi-directional charging. "You're going to see more of this, I would argue, in the future," Cook says.