Monetary-based Availability: A novel Approach to Assess the Performance of Wind Turbines

With the background of numerous wind turbines phasing out of fixed feed-in tariffs in the following years and an increasing share of negative electricity market prices on the spot market, the availability definitions of "time-based" and "production-based" availability are possibly no longer suitable for assessing the overall performance of a wind turbine. This paper introduces a novel definition: the "monetary-based" availability. The differences between the established definitions and the "monetary-based" availability are highlighted by comparing the measures on an empirical data set. Furthermore, results on the impact of scheduling planned downtimes towards a monetary-based optimum show that revenues can be increased. By shifting only a small share of the annual downtime to an optimum to maximize the revenue from electricity, a strong increase in additional earnings and thereby an increasment of the monetary-based availability can be achieved.