Answer Description
Power-line communication will allow a SOHO network to be built using ethernet power adapters which is much cheaper than running cable. Power-line communication allows the use of the ethernet protocol over electrical power wiring. If the company doesn't want employees working from home to use wireless networks or to pay the expense of running ethernet from the modem to the office then power-line is a cheap alternative.
Wikipedia
Power-line communication (PLC) carries data on a conductor that is also used simultaneously for AC electric power transmission or electric power distribution to consumers It is also known as power-line carrier, power-line digital subscriber line (PDSL), mains communication, power-line telecommunications (PLT), or power-line networking (PLN) A wide range of power-line communication technologies are needed for different applications, ranging from home automation to Internet access which is often called broadband over power lines (BPL) Most PLC technologies limit themselves to one type of wires (such as premises wiring within a single building), but some can cross between two levels (for example, both the distribution network and premises wiring)
Power-line_communication - Wikipedia, the free encyclopedia