Imagine every home around the world with a renewable energy storage system collecting emissions-free energy from rooftop solar panels and using that clean power to charge electric vehicles. Tesla Motors CEO Elon Musk on Tuesday took a big step to making this vision a reality with the announcement of a $2.8 billion stock offer to buy SolarCity, the solar installation firm that Musk chairs.

Tesla, SolarCity, Elon Musk

“Tesla’s mission has always been tied to sustainability,” the company wrote in a blog post. “We seek to accelerate the world’s transition to sustainable transportation by offering increasingly affordable electric vehicles. And in March 2015, we launched Tesla Energy, which through the Powerwall and Powerpack allow homeowners, business owners and utilities to benefit from renewable energy storage. It’s now time to complete the picture. Tesla customers can drive clean cars and they can use our battery packs to help consume energy more efficiently, but they still need access to the most sustainable energy source that’s available: the sun.”

Related: Tesla and SolarCity to add more energy storage in 2016 than the entire country did last year

Musk said the SolarCity solar panel systems will be sold under the Tesla brand. Following his announcement, Tesla shares fell more than 13 percent to $190.59 in after-hours trading while SolarCity shares jumped 19 percent to $25.26.

In March, Musk unveiled Tesla’s first affordable EV, Model 3. The car is priced at $35,000 before incentives and achieves a 215 mile range per charge. “The world does not lack for automotive companies,” Musk said on a conference call with reporters. “The world lacks for sustainable energy companies.”

+ Tesla Motors

+ SolarCity

Via CleanTechnica

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