The Excelsior Power Company was one of the many competing companies that sprung up after the Edison Company first began supplying electric power in lower Manhattan. It was a branch off of an existing company that had been selling steam, and now sold direct current. Eventually all of the little companies got swept up into the Consolidated Edison monopoly; eventually this outdated plant was decommissioned and turned into an apartment building. We’re looking at what had been the freight entrance off Gold Street – you can see the (green-painted) bollards protecting the bottom of the brick arch on either side of the infill facade.
But that’s all incidental. I took the picture for no other reason than the beauty of that lettering. There is, in my opinion, a lot to criticize in Victorian art and architecture, but that sign is fantastic.