Panasonic has also promoted the concept of interoperability between the different powerline adapter technologies through its involvement in a consortium called the Consumer Electronics Powerline Communication Alliance (CEPCA). Panasonic has recently agreed to partner with the HomePlug Alliance and submit a joint specification to the IEEE P1901 Working Group, which is working to define an industrywide data-over-powerline technology. Future products using the proposed standard would be interoperable with existing HomePlug AV and Panasonic HD-PLC units, Panasonic and HomePlug jointly announced.

Donnelly said that the UPA has been collaborating with CEPCA on proposed interoperability specifications for the P1901 Working Group. No vote on a new specification is expected until next year, he indicated, and he questioned whether anyone today can predict future compatibility with a standard that remains to be finalized.

"There are multiple proposals, and there are likely to be mergers among the proposals -- this is just Stage 1," Donnelly said. But he foresaw continued involvement by the UPA, leaving open the possibility of three-way interoperability with a future specification.

Read a review of powerline adapters here