Actual maximum demand load, and the simulation result

Hello, Our project has two sources of energy (electricity, and natural gas). We have already finished the simulation model, and its result was accepted by USGBC, when reviewed. In addition we have already contacted our government for electric supply (maximum demand load) agreement. At the moment we are thinking of having PV cells on the roof, though we are confused about; whether the percentage of the cells electric energy production should be compared with the actual maximum demand load OR the simulation results of the proposed design electricity? Thank you