Indicators to measure intraday electricity market efficiency in 18 selected Member States of the European Union

With increasing volatile wind and solar energy generation, the importance regarding designs of intraday and balancing energy markets ensuring efficient allocation of energy supply is growing. Typically yearly traded volumes and prices of intraday power exchanges and imbalances are used to analyse the market performance. This study introduces two indicators to measure efficiency in intraday electricity markets. The efficiency is measured during hours of high deviation of actual and forecasted residual load. The results of the analysis show non-complementarity of activated balancing energy to forecast deviations, thus pointing to an inefficient market. As the power plant generation mix cannot sufficiently explain the intraday market inefficiency, further research regarding imbalance regulations and incentives as well as forecast information deferral and OTC trading practice is needed.