A first-order cost analysis of Photovoltaics power generation and DG power generation for urban emergency load is presented. Six years field data of two DG sets installed at IIT, Delhi for emergency load have been thoroughly analysed to find out the requirements for such power generation model. The unit cost of emergency load energy is calculated using different parameters. These are the interest rate of commercial loan at present value of Indian market, IREDA loan facility to promote PV, the depreciation cost, operation and maintenance cost of PV and DG sets, and fuel cost of DG set. It is found that the unit cost of PV electricity is cheaper or comparable with that from DG power at present market price.