Resource estimation and load estimation are primary inputs in the designing of Hybrid Renewable Energy System (HRES). Otherwise, HRES system may become oversize or undersize without vigorous load and resource assessment. Oversizing or undersizing may also affect the economic viability of such a system in terms of higher energy generation cost and lower reliability. Proper resource estimation for hybrid energy system not only provides sustainable energy but also improves reliability and stability. In the present study, sizing optimization of a hybrid energy system, consisting of hydro-solar-battery-diesel, has been carried out. To begin with, three villages in the Chanju Panchayat of district Chamba in Western Himalayan Himachal Pradesh (HP) has been considered based on the local resource availability (corresponding to hydro and solar potential). Sizing optimization of the hybrid system (at these villages) is carried out using particle swarm optimization (PSO) method with energy index ration 1. In the designing of HRES, the input parameters such as available solar radiation and hydro discharge has been used. These parameters are estimated by using artificial neural network (ANN) and hydrology estimation techniques. Addition to the renewable energy fraction based on the present energy demand of selected villages, the cost of energy (COE), net present cost, and emissions of carbon dioxide from diesel generator are also estimated. It is worth mentioning that the use of Diesel generator is included to deal with the intermittency of the renewable energy resources. The 18 possible combinations comprising a different component has been investigated. The results present that the 15(th) combination using PSO algorithm is most cost-effective. The least cost of energy of HRES is estimated at 5.37(sic)/kWh, and the corresponding net present cost is 26288078(sic)million. The combination 3rd is most effective if renewable fraction (RF) is considered as the main objective. The total fuel used in this combination is 2218 l and share of renewable is approx. 98%.