The State Public Service Commission has already taken a few of them, including last week approving new ways to determine pricing for electricity from renewable energy projects that more accurately reflect the value to the grid based on geographic location, timing and other factors yet to be determined. But Lawrence Orsini, LO3’s chief executive, said the state still needed to determine how to define his company and its network of participants before it could get its market up and running, a move he anticipates by June.

“There’s nothing technically infeasible about what we’re doing,” he said. “In order for transactive energy to take off as a whole, regulators have to be comfortable that markets can actually work this way and, more importantly, that people want markets like this.”

Over the past year, LO3 has been working to find those people, using Google Earth to identify homes with rooftop solar installations and then knocking on doors to enlist participants, with some success throughout Park Slope and Gowanus.

On a block of President Street last year, the company carried out two sales of green electricity credits generated by one homeowner’s solar system to a neighbor across the street — tiny transactions, but important in proving the concept’s viability.

Those sales involved test versions of renewable-energy credits — numbered certificates that are used to track electricity exported from a renewable system to the grid. Utilities, corporations and other customers can buy the credits to claim green energy use.

In the Brooklyn case, LO3 used the credit sales, conducted over PayPal, to test its approach; it cannot legally buy and sell electricity until regulators determine its market status. Once that occurs, Mr. Orsini said, the company will be able to facilitate the trading of energy among its participants — though they would still pay the utility, Con Edison, for infrastructure fees and services, as customers now do when they choose to use a green energy supplier through the utility.