The Role of the European Investment Bank in Financing Renewable Energy Sources in Selected European Union Countries

In the area of the European Union (EU) energy policy, among the entities involved in the process of financing investments in renewable energy sources (RESs), the European Investment Bank (EIB) plays a particularly important role. Therefore, the aim of the research was to identify the relationship between the EIB’s financing of RES projects and the level of energy transition, measured by the share of RES in gross final energy consumption (RE). The goal was achieved using quantitative methods and a two-way fixed-effects panel model FE (country and year), based on data from EIB, Eurostat, World Bank, OECD, EDGAR, and Our World in Data for 2012–2023. As a result of the research, it was determined that the scale of EIB financing alone does not translate into short-term growth of the RE in the examined sample (EU countries). Indeed, the effectiveness of funding depends on the regulatory and institutional context; the grid’s ability to absorb new capacities (throughput, storage, demand flexibility); and from the time horizon (delayed materialization of effects). Increasing the efficiency of converting euros into RE percentage points requires better targeting (power + grid), simplification of procedures and good financial assembly with the right allocation of risks.