1. A method of disaggregating power at a site, said method comprising: identifying a first time interval when only a single first load is operating at said site; determining a first load power used during said first time interval by said first load; fitting a model using selected sensor data of said site during said first time interval and said determined first load power; determining a second load power used by said first load during a second time interval during which at least one other second load is operating using said model; and outputting said first and second load powers.