1. A method executable using at least one computer having at least one processor and memory located within a community energy management system (CEMS), the method comprising: monitoring, using a sensor of the CEMS, electricity supplied to a community by monitoring a feeder line from a local utility, the community comprising a plurality of consuming units, the community being a subset of a power grid; detecting a reduction or loss in electricity supplied by the local utility during one or more time periods for which backup power will have to be provided; monitoring, using at least one sensor of the CEMS, electricity consumption at the plurality of units; determining, using the at least one processor, backup power consumed on a per-unit basis during the one or more time periods; and calculating, using the at least one processor, costs to respective units based on per-unit consumption of the backup power during the one or more time periods.