Tesla Powerwalls for Home Energy Storage Are Hitting U.S. Market - Bloomberg

Later in the article: "“We’re confident that we will sell or lease every one,” said [Green Mountain Power] CEO Mary Powell. “We’re trying to transform a 100-year-old electric grid, and Tesla is killing it in terms of driving down cost while constantly improving the technology.”"

"A year after Elon Musk unveiled the Powerwall at Tesla Motors Inc.’s design studio near Los Angeles, the first wave of residential installations has started in the U.S. The 6.4-kilowatt-hour unit stores electricity from home solar systems and provides backup in the case of a conventional outage. Weighing 214 pounds and standing about 4-feet tall, it retails for around $3,000. But hookup by a trained electrician is required, as is something called a bi-directional inverter that converts direct-current electricity into the kind used by dishwashers and refrigerators. The costs add up quickly -- which has fueled skepticism about Musk’s dream of changing the way the world uses energy.
Net-metering policies, which allow residential solar customers to sell their excess solar electricity back to utilities, have limited the appeal of home batteries in many states. But that’s shifting: Net metering is being phased out in some states, making storage more attractive."

Tesla Powerwalls for Home Energy Storage Are Hitting U.S. Market - Bloomberg