Rural electrification represents a great worry for developing nations. Isolated microgrids establishment is the brightest solution for this problem. Optimization strategies for mathematical simulation and modelling are accomplished in this research to size an isolated residential microgrid in Egypt consists of wind generators (WG), photovoltaic (PV), battery energy storage system (BESS) and Biomass generator. This paper’s novelty relies on the techno-economic performance comparison of three sizing strategies of isolated microgrid based on renewable sources, considering the sources’ uncertainty. Also, the environmental and economic effects of using rice straw in biomass gasification are introduced to handle the problem of dark clouds from its open-air burning. Three categories with nine combinations of renewable energy sources (RES) are introduced in this paper to select the ideal option. Multi-objective genetic algorithm (MOGA) optimized the systems under both deterministic and stochastic conditions, taking into consideration the uncertainties of solar radiation and wind speed using Monte-Carlo techniques. The obtained results are compared with the results of epsilon multiobjective genetic algorithm (ε-MOGA). Simulation outcomes show that PV with BESS is the most economical option for microgrid sizing with a total system cost of $ 4.04 million. Besides, Scenario 6’s hybrid system provides an appropriate ecological-reliable configuration, especially when considering sources’ uncertainties.