In this study, different impacts of distributed energy resources (DERs) expansion scenarios on the flexible reliability (FR) and overall reliability (OR) indices of hybrid AC–DC microgrid have been investigated. A procedure for calculating the FR and OR indices is introduced. Then, a sensitivity analysis is carried out to reveal the impacts of DER expansion on the OR and FR indices. It has been shown that some DER technologies may improve the OR indices, but impose some negative impacts on FR indices or vice versa. Indeed, OR and FR indices are highly dependent on the type and capacity of each DER technology and the topology of the microgrid. The results of this study show that each DER technology has a unique impact on OR and FR indices and variation of the capacity of each DER technology reveals a specific trend in changing the OR and FR indices.