I could write more, but this isn't the place for an essay on electric motor history. Since many VCs are on here, I suggest "The Electrical Manufacturers, 1875-1900 A Study in Competition, Entrepreneurship, Technical Change, and Economic Growth", by Harold C. Passer. This is a Harvard Business School book. It's like reading about the dot-com era, a century earlier. All the little startups, the patent battles, the consolidation, and finally duopoly - Westinghouse and General Electric.

That book has Edison's business plan numbers for the first power station, Pearl St. in NYC. Overoptimistic payback calculations and all. The margins were quite high. Gas lighting was expensive and electric light was much cheaper to provide, so Edison could and did mark it up a lot. Electric lighting was very profitable, which sped deployment. Initial sales were slow, though. The bottleneck was marketing, not the technology.

[1] http://www.hup.harvard.edu/catalog.php?isbn=9780674423640