In this study, updating parameters of smart inverters (SI) based on the change of PV penetration rate and weather conditions was evaluated. Among a wide variety of functionalities of SI, we focused on Volt-VAR control and comprehensively investigated the voltage profile in distribution network (DN) for various parameters. For the scenario in which PV penetration rate or weather condition was changed, we compared the total energy loss for the updated and fixed parameters, while avoiding voltage violation. We found that the maximum reduction rate of energy loss by appropriately changing the Volt-VAR parameters was 14.4% and 13.7%, respectively for the two cases, and that the parameters should be preferably updated according to the condition of DN from the view point of reducing energy loss. Quantitative results of Volt-VAR parameters survey were summarized, which can be a guide for how to use the functionality when PV is heavily installed in DN.