Invites have gone out for this week's Tesla event in Hawthorne, California, just outside Los Angeles at the company's headquarters. There's not much to go on, but what's here is significant and notable: the invitation teases "the missing piece" with the subtle outline of a white box.

Tesla is widely expected to unveil a battery cabinet for homes that would better enable solar energy to be stored, lessening reliance on the grid. A recent report by The Guardian suggests that the cabinet will be available in white or black and will be rented, not bought, for a $1,500 fee followed by small monthly payments — a much easier pill to swallow than an upfront fee that could go into five figures. (It's no surprise that batteries represent a significant portion of the cost of a Model S.)

Elon Musk's car company is in the process of building out the so-called Gigafactory, a Nevada-based facility that will be able to produce many more lithium ion batteries than are available to the company today — and do so at a far lower per-unit cost. Beyond cars, Tesla will have the ability to provide batteries to other industries, and that includes home solar. (Musk is also the chairman of home solar provider SolarCity, through which Tesla's batteries are expected to be offered.)

We'll be covering the event live from Hawthorne this Thursday, April 30th.