First a little history (those that ignore history get to repeat the mistakes) BPL (AKA PLC/PLT/DPL) is a tired old legacy technology that has struggled with interference issues since it was first rolled out in Manchester, England in 1997 (one year before the introduction of DSL to Europe). Nortel designed the system. The UK authorities tolerated the interference for a time but when the emergency services traced interference to BPL it was shut down.
Development moved to Germany, Nortel struggled on and eventually decided that the interference issues could not be resolved. Siemens then took up the lead, after several thousand customers had been connected up, Siemens came to the same conclusion as Nortel and exited the business. The next company to enter the business was Ascom based in Switzerland. Then an Israeli company called Mainnet entered the BPL market using chips from a Spanish company called DS2.
Tests were made in Japan and the authorities banned BPL due to the interference problems. Next Finland shut down their BPL system due to interference problems.
By 2003 there were 7,000 users in Europe with a multitude of test sites all small scale. BPL customer growth was stagnant.
The U.S. was never considered a market for BPL because of the architecture of the electrical distribution system. In most of Northern Europe electrical distribution is underground with about 200~300 houses for each transformer. In the U.S. much of the electrical distribution is overhead with up to 6 houses sharing a transformer.
In what can only be described as a desperate last ditch attempt to sell product and survive, the BPL industry created a "phantom" product that answered the FCC's need for rural broadband. The myth was propagated that BPL was the answer to rural broadband deployment. The FCC commissioners bought the story, the press talked about Internet at every socket.
The reality is that of all the Internet distribution technologies BPL is the least suited to go any distance. Every 2,000 feet an expensive repeater in needed to boost the signals.
Now to the myths
Clean technology myth Tales of interference had preceded BPLs arrival, the myth that the interference issue had been solved (first generation problem!) was told to anyone who would listen. The lobbyists were very successful, they managed to get an FCC commissioner to state that the interference complaints were "unsubstantiated". How the interference problem had been solved was not made clear.
The reality is that the interference is even worse than ever, the modulation technique has been changed so that the interference sounds like noise and for many users it will look like a faulty radio issue. Tracking the source and proving the cause will be difficult.
High speed myth To add speed to the solution for rural broadband was "icing on the cake". To create the illusion of speed, trial/demo systems where set up where four or five users enthused about speeds in the megabit range. BPL is a shared system and real world results with typical economic user numbers are about 250K (Broadband? more like Midband).
In conclusion The only people who will profit from BPL are the power companies who will roll out niche systems in the few markets where the economics make sense. It will only take a few systems to trash the radio spectrum for a substantial portion of the western hemisphere.
There are many better ways to provide Internet access, when the choices are rated, BPL but any test comes bottom of the list however you make the measurement.