Before revision:  Energy-based power markets are, however, facing several market distortions, namely from the gap between the electricity volume traded at spot markets versus the overall electricity consumption as well as the (wrong) regulatory assumption that variable RES generation, i.e., wind and PV , truly have zero marginal operation costs.
After revision:  Energy-based power markets are, however, facing several market distortions, namely from the gap between the electricity volume traded at spot markets versus the overall electricity consumption as well as the (wrong) regulatory assumption that variable RES generation, i.e., wind and photovoltaic (PV) , truly have zero marginal operation costs.