Spatial Inequalities in Grid Connection Capacity for Renewable Energy Sources: Evidence from Polish Distribution Network Data

Poland’s rapid expansion of renewable energy sources (RES) and of distributed photovoltaics (PVs) in particular has increasingly collided with a finite and unevenly distributed resource: available capacity in the electricity distribution grid. This paper examines grid-connection capacity as a spatial constraint on RES development in Poland, combining a national overview of grid congestion (2023–2026) with a quantitative case study of the 52 coherent 110 kV node groups administered by ENERGA-OPERATOR S.A. under the statutory reporting regime of Article 7(8l) of the Polish Energy Law. The node-group figures are not an observed annual series: the operator’s disclosure gives the capacity available in the base year of 2018, together with the capacity it planned to make available in each year up to 2023, so the analysis characterises the spatial distribution implied by the operator’s own five-year development plan rather than realised outcomes. Using descriptive statistics, a Gini coefficient, Lorenz curve analysis, and an original growth index (the ENERGA Grid-Connection Growth Index, EGCI) developed for this study, we show that available connection capacity is markedly unequally distributed across node groups (Gini = 0.48 in 2018, rising to 0.51 by the 2023 planning horizon) and that this inequality has a distinct regional pattern: the Olsztyn branch, corresponding to the Warmia–Mazury region (Warmińsko-mazurskie voivodeship), more than doubles its share of the operator’s total available capacity under the plan (from 12.4% to 29.3%, or from 75 MW to 365 MW in absolute terms), moving from the third-lowest to the highest planned capacity among the operator’s six branches, while two of its nine node groups—including the regional capital’s own—receive no increase at all under the plan. A voivodeship-level spatial analysis, mapped using verified administrative boundary data, shows a pattern consistent with this at a national scale: Warmia–Mazury has the second-lowest installed generation capacity of Poland’s 16 voivodeships despite favourable land and irradiation conditions for photovoltaic development. Bootstrap analysis confirms this robust level of inequality while indicating that, with 52 units, the five-year increase is best read as a consistent tendency rather than as a statistically established widening; the operator-level values are specific to ENERGA-OPERATOR and are not numerically generalisable to Poland’s other four operators. We discuss the implications of these findings for grid-investment planning, RES-integration policy (cable pooling, storage co-location, curtailment reduction), and the energy-security dimension of an increasingly decentralised, weather-dependent generation system, and we identify concrete directions for future quantitative and spatial research.