Before wave energy converter (WEC) arrays can be used to generate electricity at large scale, their environmental impacts need to be understood. Here, we examine the impact of large-scale WEC array operation on sand bars. Sand bars have an important role in natural coastal processes, since they protect out coastlines from the impact of storm waves. Since the wave climate between a WEC array and the coast will likely be modified by large-scale energy extraction, this could disrupt the natural process which maintains sand bars, affecting the location of wave breaking. We examine this hypothesised impact through application of a 1D cross-shore wave and sediment transport model. The model is applied initially to simulate natural sand bar formation. Wave energy is subsequently extracted at the model boundary, representing WEC array operation, and the morphodynamic impact assessed. Our results demonstrate that, under certain conditions, WEC array operation can lead to enhanced sand bar formation. Since reduced wave breaking, WEC array operation could provide enhanced coastal protection from storm waves.