Elon Musk on Tuesday sought to build a clean energy powerhouse as his electric car maker,  Tesla Motors made an offer to buy his solar installation firm SolarCity Corp in a stock deal worth as much as $2.8 billion Musk, who is the chairman of SolarCity, CEO of Tesla and the largest shareholder of both companies, described the deal as a "no brainer"  "Instead of making three trips to a house to put in a car charger and solar panels and battery pack, you can integrate that into a single visit," Musk told reporters "It's an obvious thing to do."