Classification of European Union member states according to renewable energy production. Observations from two decades

The research objective is to identify clusters of European Union member states similar in terms of electricity generation from renewable energy sources between 2004 and 2023. The diversification of renewable energy sources across the European Union member states was evaluated and juxtaposed dynamically using multivariate comparative analysis methods. Four groups of similar countries were distinguished. The results have confirmed the research hypothesis that most clusters of the European Union member states are similar in electricity generation from renewable energy sources after the accession, including countries that joined the organisation both before and after 2004. The study improves the state of the art regarding the classification and clustering of member states regarding electricity generation from renewable energy sources over two decades following the most significant enlargement. The novelty lies in the new time framework, which covers all years from 2004 to 2023.