Tesla's 'major new product line'-is it a battery?

On Monday, Tesla (TSLA) Chief Executive Elon Musk took to Twitter to tease a new product announcement : "Major new Tesla product line—not a car—will be unveiled at our Hawthorne Design Studio on Thursday at 8 pm, April 30."

The tweet fueled a tidal wave of speculation from Wall Street and news outlets that the mystery product would be a stationary battery storage system for residential customers. There's still no firm indication that what Musk will debut will be a battery system, or anything related to energy, for that matter. But there's reason to guess that it could be. (Tweet This)

Tesla has confirmed nothing ahead of next month's announcement, but here's what Musk himself said on the electric carmakers' February earnings conference call: "We're going to unveil the Tesla home battery or the sort of consumer battery that will be for use in people's houses or businesses fairly soon. We have the design done, and it should start going to production probably in about six months or so. We're trying to figure out a date to have the product unveiling, but it's probably in the next month or two months."

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The company's been testing residential stationary batteries in roughly 200 to 250 California households, according to a Global Equities Research analyst note from Monday, and it already supplies lithium-ion batteries (which it also uses in its electric cars) to sister company SolarCity (SCTY) (also founded by Musk).

Presumably, once Tesla's $5 billion lithium-ion battery plant—dubbed the " gigafactory "—gets up and running, large-scale production could be done from there as well.

If some sort of battery is indeed the product on tap at April's event—and with the caveat that the world outside Tesla's Palo Alto, California, headquarters has few details in the meantime—it could become part of a much bigger discussion not only for the future of Tesla, but for power generation.