The output of the Load Aggregator are six numbers per calendar month, corresponding to the total energy consumption and maximum demand in each of three time periods (peak, off-peak and shoulder). These values, along with identification of the chosen tariff, are sent to the TAP bill calculator using a SOAP interface. Bills are calculated for the specific tariff using the TAP bill calculation web service. This terminology is drawn from TOU tariffs, but essentially the same method applies to standard tariffs with only one time period. For non-TOU tariffs all the energy is allocated to the “off-peak” bin. Time periods are defined differently for each utility or in some cases for each tariff.