Cost-efficiency screening of renewable energy connections in distribution networks: Evidence from a Czech DSO

The rapid deployment of intermittent renewable energy sources (RES), particularly solar photovoltaic (PV) systems, creates technical and economic challenges for distribution system operators (DSOs). This study develops an application-level cost-efficiency screening framework and applies it to approximately 156,000 PV connection applications processed by a Czech DSO in 2020–2024. The framework relates project-specific reinforcement expenditure to requested capacity (EUR/kW) and compares the indicator with a scenario-dependent economic threshold that can be periodically recalibrated. At low voltage (LV), 1393 MW, or 93% of the 1493 MW approved capacity, required no project-specific reinforcement at the time of application; this represents zero marginal reinforcement cost rather than zero total network cost because hosting capacity reflects earlier network investment. The portfolio-wide capacity-weighted reinforcement cost was 216 EUR/kW at LV and 35 EUR/kW at medium voltage (MV), whereas the reinforcement-linked LV subset reached approximately 3230 EUR/kW. Under the reference assumptions, the screening thresholds are approximately 120 EUR/kW at LV and 920 EUR/kW at MV. In a supplementary LV request-level extract, 3.1% of applications had non-zero reinforcement costs, and approximately 2.3–2.8% of all applications would be flagged under the reference threshold. Villages accounted for 58.8% of reinforcement-linked LV capacity, compared with 51.3% of capacity connected without project-specific reinforcement. The framework is intended as a screening trigger, not an automatic rejection rule, and should be complemented by flexibility options, future hosting-capacity benefits, legal safeguards, and broader social cost-benefit assessment.