SolarCity and the Solar Roof

SolarCity, founded in 2006 on an idea from Musk (who chaired it and was its principal backer), pioneered no-money-down residential solar and became one of America's largest solar installers. In November 2016, Tesla acquired SolarCity for about $2.6 billion, folding it into Tesla Energy.

Alongside the acquisition, Tesla unveiled the Solar Roof — solar cells built into attractive glass roof tiles, so a home could generate its own power without bolt-on panels. Combined with the Powerwall, it offered homeowners a complete clean-energy system.

The deal gave Tesla a vertically integrated clean-energy stack: generate electricity with solar, store it with Powerwall and Megapack, and use it to drive with electric cars. It tied the company's product line directly to its founding mission — accelerating the world's transition to sustainable energy across every part of how people power their lives.