How focused are you at your one big thing?

Today Elon Musk got the green light to merge two of his companies, Tesla and SolarCity – opening the way for a fully integrated solar powered solution to live a zero carbon life.

“We’re trying to make an integrated product,” Musk told Tesla shareholders today. “So you have an integrated solar roof with a Powerwall and an electric car, and you just go into a Tesla store, just say yes, it just happens. It all works, it’s seamless and you love it.”

Just five months ago, in June Elon was under se...