Two months prior to the announcement of "gigafactory" plans that is causing nerd orgasms all over the tech and auto sphere, another of Musk's interests, SolarCity (SCTY) announced a new program that would provide large batteries to businesses to help them lower peak demand rates.
The program, DemandLogic, announced in early December, couples the solar panel installations that SolarCity is known for with refrigerator-sized batteries that store up to a third of the solar power. Specially design software can be programmed to take advantage of that stored electricity during times of peak demand.
According to the company's press release, peak demand costs for electricity have been rising faster that rates generally, putting a strain on businesses. Using the DemandLogic program, businesses can smooth out that energy demand from utilities, reducing energy costs.
Musk is chairman of SolarCity's board. Who manufactures the batteries for DemandLogic? Tesla, of course. From Tesla's recent 10-K, with my emphasis added:
The Tesla Gigafactory is currently expected to attain full production capacity in 2020, which is anticipated to be sufficient for the production of approximately 500,000 vehicles annually and stationary storage applications.
Granted, any benefit to Tesla from a ramp up in "stationary storage" orders for SolarCity's DemandLogic will be miniscule compared to the 500,000 planned Tesla autos. But it certainly makes a nice, small hedge against any problems encountered meeting that goal. And it is just one more example of how Musk sees the three companies, Tesla, SolarCity and SpaceX, as an interconnected web.