TOTALLY GEEKED!

Tesla Motors launched late Thursday its Tesla Energy brand with a line of batteries designed for homes, businesses and utilities. 

"The obvious problem with solar power is that the sun doesn't shine at night," the company founder and CEO Elon Musk said in a press conference in California. "We need to store the energy to use at night."

Musk launched the Powerwall home battery, a rechargeable 7-10 kwh lithium-ion battery, priced at $3,000-$3,500 for installers, with deliveries slated in three to four months. It's available in a selection of colors.

The size is 130 cm (51.2 inches) high, 86 cm (34 inches) wide and 18 cm (7.1 inches) deep.

"You don't need a battery room …A normal household can mount this on their garage or the outside wall of their house and it doesn't take up any room. It's flat against the wall," Musk said. "It's designed to work with solar system out of the box."

Tesla will need to open more "Gigafactories," in addition to the one planned as well as offering open sourcing of the technology, Musk said. Tesla plans to build the battery packs at its $5 billion Gigafactory just outside of Reno, Nevada. The massive plant will employ 6,500 workers and has the potential to crank out a half-million lithium-ion batteries by 2020.

Musk estimated that transitioning all global transportation,electricity generation and heating to renewable energy, primarily solar, would require around 2 billion of his Powerpack batteries, the model designed for business-level usage.

That compares with around 2 billion cars and trucks on the road globally, while another 100 million vehicles are made yearly, Musk noted.

"We have done things like this before. It's not impossible," Musk said.

For remote locations, Musk said he expected the type of tech disruption that followed the advance of mobile phones for people who lived in areas without land-line telecommunications coverage.

At one point, he noted the press conference was being powered by Tesla's batteries and solar power, without using grid power.

How realistic is Musk's vision?

"The goal is to change the world, starting with the automotive industry and closely followed by the power sector and then energy in general. Is that a realistic goal? Clearly it is not. But it is useful to remember that Elon Musk's other business involves flying to Mars," Bernstein analysts said in a report published before the Tesla press conference and subtitled "Mama Musk didn't raise no realist."

But it added, "Realistic goals are not really the point of the exercise. Transformational technologies and applications are. In short, either the Gigafactory is way too big, or not nearly big enough. We believe (as they do clearly) that it is the latter."

Bernstein, generally bullish on solar power, projects "massive, unprecedented growth in lithium-ion batteries," adding "the curious thing will be why Tesla ever bothered building cars when all the value was in the battery."

Others have been more skeptical of the potential for battery storage.

"I just don't see the value of that in stationary products," said the CEO of Vilas Capital, John Thompson, during "Closing Bell" before the announcement. "It just doesn't seem to be something that is consistent with its cost disadvantages versus more traditional battery technologies."

"Tesla, we think, is a classic example of people becoming too excited about a fast-growing company and overpricing the stock by a huge margin," said Thompson.

Colin Langan at UBS also said he was cautious on the outlook.

"Getting battery cost down is key, but on the stationary storage side there is a lot of questions about which chemistry will dominate long term. It might not be lithium," Langan said prior to the press conference.

Tesla shares have soared more than 18 percent higher in the last month.