Silicon Carbide (SiC) is a wide bandgap semiconductor that is currently of major interest for power electronics applications. SiC-based semiconductor devices and circuits are presently being developed for use in high-temperature, high-power, and/or high-radiation conditions under which conventional semiconductors lose their efficiency. However, the blocking capabilities of SiC power rectifiers and transistors are yet to approach their impressive theoretical limit due to so called edge effects at the device periphery. Surface passivation, which addresses many issues related to surface electric fields, is an extremely important fabrication step for high performance semiconductor electronic devices. Surface passivation can influence the surface recombination velocity, surface charge, interface trap density, and other surface characteristics. In this work, two-dimensional device simulations are used to establish the trends and the extent of the influence of charges, present in surface passivation dielectrics, on the reverse bias characteristics of SiC devices. Actual charges and charge instability are experimentally evaluated in a few common types of passivation dielectrics used in SiC device technologies. Device simulations are used to predict the corresponding improvement (or degradation) of the breakdown conditions at the device periphery, associated with the experimentally measured dielectric charges.