California’s goal of merging rooftop solar systems, smart inverters, behind-the-meter batteries, real-time energy management systems and other distributed energy resources with its utilities’ grid plans faces a major challenge before it even gets underway -- the data-sharing challenge. Over the past nine months, the state’s big investor-owned utilities and its big distributed energy companies -- SolarCity in particular -- have been staking out positions on how much data they need to share with each other to overhaul utility planning on the grid edge, and how little has b...