Tesla Motors Inc’s plan to generate new revenue by repackaging electric car batteries as home and business power storage systems faces stiff competition for both customers and the government subsidies that are critical to the market’s growth. At the unveiling of its suite of storage battery systems on Thursday, Tesla Chief Executive Elon Musk said at a company event near Los Angeles the new Tesla Energy was far ahead of its competition in offering an integrated system for generating solar power and storing it on-site.