Hybrid energy systems have provided a promising way to realize nearly/net zero energy buildings (nZEB) including isolated buildings in remote areas and grid-connected buildings. This study aims to investigate and compare several typical hybrid energy systems (HESs) for designing grid-connected nearly/net zero energy buildings (nZEB). Specially, an exhaustive searching method and Monte Carlo simulation are utilized to optimize hybrid energy systems for Hong Kong Zero Carbon Building considering uncertainty impacts. The performance of nearly/net zero energy buildings is evaluated in terms of a combined performance comprised of the cost, CO2 emissions and grid interaction index. Subsequently, the effects of design mismatch ratio, weighting factor combination and the probability to be nZEB on the performance are analyzed and compared under the four hybrid energy systems. The study results show that the probability for a building to achieve annual energy balance is highly depending on the design mismatch ratio, and the correlative dependencies between the two parameters are fitted in formulas for the studied hybrid energy systems. In addition, an nZEB designed with PV& BDG system is found to have a robust performance compared with that designed with other three hybrid energy systems under the same design condition. (C) 2017 Elsevier Ltd. All rights reserved.