The determination of type of generation technology suitable for an autonomous power system calls for comprehensive planning. In this paper, a systematic approach for determination of optimal mix of resources is presented for an autonomous hybrid power system. The considered constituent resources comprise of diesel, photovoltaic, wind and battery storage. A techno-socio-economic criterion is formulated in order to determine optimum combination of resources. Reliability evaluation forms the basis of planning problem and has been carried out using analytical technique. The proposed formulation has been analyzed for different resource mix configurations for an autonomous power system located in Jaisalmer, Rajasthan, India. Particle Swarm Optimization (PSO) has been used to determine optimal component sizing for each of the configuration.