Before revision:  In this paper we analyze the impacts of wind and PV power in-feed on the spot market for a region that is already today experiencing significant FIT-subsidized RES power in-feed ( \%), the German-Austrian market zone of the EPEX. We show a comparison of the FIT-subsidized RES energy production volume to the spot market volume and the overall load demand. Furthermore, a spot market analysis based on the assumption that RES units have to feed-in with their assumed true marginal costs, i.e., operation, maintenance and balancing costs, is performed. Our analysis results show that, if the necessary regulatory adaptations are taken, i.e., increasing the spot market's share of overall load demand and using the true marginal costs of RES units in the merit-order, energy-based power markets can remain functional despite high RES power in-feed .
After revision:  In this paper we analyze the impacts of wind and PV power in-feed on the spot market for a region that is already today experiencing significant FIT-subsidized RES power in-feed ( \%), the German-Austrian market zone (\approx\,20\% FIT share). Our analysis shows that, if the necessary regulatory adaptations are taken, i.e., increasing the spot market's share of overall load demand and using the true marginal costs of RES units in the merit-order, energy-based power markets can remain functional despite high RES power in-feed .