"This is just a guess right now, but maybe somewhere around 20%," said Musk. Of course, that would by the profit margin for stationary storage products once the company hits mass production at the Gigafactory in 2017.
What percentage of the lithium-ion battery production will go stationary storage products and how much will go to Tesla electric vehicles?
Even though cars will get the priority over batteries, stationary storage could wind up taking much of the Gigafactory's capacity.
Musk sums it up by adding, "It feels like the stationary storage demand is just nutty."
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You get the point.
While Tesla is in the midst of a critical year for its vehicles – the Model S and soon the Model X SUV – it's the battery business that is grabbing the spotlight right now.
Skeptics will say Musk is using the stationary storage business to distract investors from asking hard questions about the Model X and the Model 3.
The fact is, those questions have been difficult and will be asked. But for now, Tesla's battery biz is the focus for many on Wall Street.
Questions? Comments? BehindTheWheel@cnbc.com.