Overnight on Twitter, Musk announced: "Major new Tesla product line — not a car — will be unveiled at our Hawthorne Design Studio on Thurs 8pm, April 30". That's 1pm on Friday, May 1, Australian Eastern Standard Time.
His pronouncement has, naturally, started a bout of the great internet guessing game.
Most theories centre on a declarations by Musk during Tesla's earnings calls in February and last year. In those calls he stated that Tesla was working on battery pack capable of powering a home or business.
During the most recent call with investors in February, Musk said: "The design [is] done and it should start going into production probably in about six months or so. We're trying to figure out a date to have the product unveiling. It's probably in the next month or two."
In addition to being Tesla's CEO, as well as the founder and CEO of SpaceX, Musk is also the chairman of SolarCity. SolarCity sells, leases and installs solar panels for businesses and private homes.
SolarCity also offers an energy storage solution to business and government clients in some markets. Dubbed DemandLogic, the system uses a large bank of batteries supplied by Tesla to store solar energy for use during the hours when electricity costs are the highest.
If Tesla's new product is indeed a home version of SolarCity's DemandLogic battery system, it will be smaller and cheaper. Last year Musk also stated that any Tesla-branded home battery offering would likely be "something flat, five inches [12.7cm] off the wall, wall-mounted, with a beautiful cover, [have] an integrated bi-directional inverter, and [be] plug and play".