Power fluctuations generated by most oscillating wave energy converters without significant amounts of energy storage may have a negative impact on the power quality of the local grid to which they are connected. Assessing this impact on the local network of a potential test site is hence an important step in the selection process of a suitable deployment location. However, site-specific grid impact assessment studies are relatively time-consuming and require a detailed model of both the farm network and of the local grid to which it is connected. Both of these constraints mean that grid impact studies are usually not performed in the preliminary stages of the site selection process, despite the important consequences resulting from poor power quality. This paper details a comprehensive study based on a relatively typical design of wave farms and covering network types ranging from very weak to very strong. The study was performed using electrical power time series of an OWC (oscillating water column) device realised in the frame of European FP7 project " CORES ". Simulations were performed using DIgSILENT simulation tool " Power Factory " .