Energy startups Nest and Opower are members of an elite club: venture capital-backed companies that have managed to find some success building software and hardware around managing home energy consumption.Several years ago when the companies launched, they focused on very different products and business models.However, over the years the companies have moved ever closer to becoming direct competitors, and now stand in the interesting position of being two of the leading startups competing in a variety of ways to reduce consumers’ home energy use.That Nest and Opower have emerged as the leading companies fighting over this business says something about the small and slow-moving industry.Over the years the market for devices, websites and services that attempt to get consumers to reduce their energy use — a largely unsexy and unappreciated task — has been riddled with struggling startups and failed clunky product launches.