Electric car maker still expects to make 500,000 vehicles by 2018, not 2020 as originally planned.
The electric car-maker has acquired the solar panel installer for $2.6 billion, pending regulatory approvals.
Tesla chief Musk has a 22% stake in the solar panel installation company.
Factory would manufacture enough panels to produce 1 gigawatt of peak power to outfit 200,000 homes annually.
Offered first to commercial customers, pilot program underway for residential use.