Evaluating the market splitting determinants: evidence from the Iberian spot electricity prices

This paper aims to assess the main determinants on the market splitting behaviour of the Iberian electricity spot markets. Iberia stands as an ideal case-study, where the high level deployment of wind power is observed, together with the implementation of the market splitting arrangement between the Portuguese and the Spanish spot electricity markets. Logit and non-parametric models are used to express the probability response for market splitting of day-ahead spot electricity prices as a function of the explanatory variables representing the main technologies in the generation mix: wind, hydro, thermal and nuclear power, together with the available transfer capacity and electricity demand. Logit models give preliminary indications about market splitting behaviour, and then, notwithstanding the demanding computational challenge, a non-parametric model is applied in order to overcome the limitations of the former models. Results show an increase of market splitting probability with higher wind power generation or, more generally, with higher availability of low marginal cost electricity such as nuclear power generation. The European interconnection capacity target of 10% of the peak demand of the smallest interconnected market might be insufficient to maintain electricity market integration. Therefore, pro-active coordination policies, governing both interconnections and renewables deployment, should be further developed. •Assess determinants on market splitting behaviour of Iberian electricity markets.•Logit and non-parametric models to express market splitting probability response.•Explanatory variables: wind, hydro, thermal and nuclear power; ATC and demand.•Results: increase of market splitting probability with higher availability of low marginal cost electricity.•Coordination policies governing both interconnections and renewables deployment.