PJM Interconnection (PJM) is a regional transmission organisation (RTO) that coordinates the movement of wholesale electricity in a market that serves nearly 20% of the US economy. The organisation serves approximately 51 million customers and has a generating capacity of 164,000 megawatts.

PJM members wishing to buy or sell wholesale electricity have four choices. First, they can 'self supply', which means that they generate their own electricity at whatever price it costs them