In 2016, Tesla acquired solar panel installer and financier SolarCity for $2.6 billion and the assumption of $3 billion in debt. Investors were skeptical of the deal from the beginning ...

SolarCity is using Tesla Motors' advanced battery technology to deliver the stored energy. Tesla's role in DemandLogic is providing the software that manages the discharge of stored energy.

This news wasn't all that surprising given Tesla's recent proposal to buy SolarCity, a solar company of which Musk is the chairman. SolarCity's CEO, Lyndon Rive, also happens to be Musk's cousin.

But as a better indicator of how the Powerpack fits into solar installation, SolarCity is using Tesla's 52 MWh Powerpack to bring 20 years of power to the Hawaiian island Kaua’i. SolarCity built ...