Brooklyn is known the world over for things small-batch and local, like designer clogs. In a promising experiment in an affluent swath of the borough, dozens of solar-panel arrays spread across rowhouse rooftops are wired into a growing network. Called the Brooklyn Microgrid, the project is signing up residents and businesses to a virtual trading platform that will allow solar-energy producers to sell excess-electricity credits from their systems to buyers in the group, who may live as close as next door. The project is still in its early stages it has just 50 participants thus far " but its implications could be far reaching. The idea is to create a kind of virtual, peer-to-peer energy trading system built on blockchain, the database technology that underlies cryptocurrencies like Bitcoin. The ability to complete secure transactions and create a business based on energy sharing would allow participants to bypass the electric company energy supply and ultimately build a microgrid with energy generation and storage components that could function on their own, even during broad power failures. "The long-term goal is to be at least partially independent of the grid in emergencies, which was a reasonable argument to join," said Patrick Schnell, whose Gowanus basement flooded during Hurricane Sandy in 2012. "Hopefully it will expand and more people will join and it will be more worthwhile."