Brooklyn is known the world over for things small-batch and local, like designer clogs, craft bourbon and artisanal sauerkraut.

Now, it is trying to add electricity to the list.

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.