Curtailment pressures and grid flexibility in Brazil: Lessons from the fast-rising distributed generation

The accelerated expansion of micro and mini distributed generation (MMDG), predominantly photovoltaic, has introduced new operational challenges to Brazil's hydro-thermal power system. Since MMDG supplies load directly at the distribution level, it reduces the net demand visible to the transmission grid. This thread is reshaping the national net-load curve by deepening the midday valley and steepening the evening ramp that centrally dispatched resources must supply. Although the duck curve phenomenon and its curtailment implications have been widely studied internationally, quantitative evidence for hydro-dominated systems remains limited. In this context, the present study applies a data-driven analysis of hourly operational data from 2024 to evaluate how MMDG growth affects net-load variability, modifies ramping behavior, and influences curtailment exposure in the Brazilian National Interconnected System (SIN). To this end, the analysis addresses two guiding questions: (i) how the expansion of MMDG reshapes the aggregated load curve and alters intraday variability, and (ii) how its production profile relates to curtailment events classified as energy imbalance (ENE) in centralized wind and solar plants. By examining these aspects together, the study provides system-level evidence particularly relevant to hydro-based electricity systems undergoing rapid distributed PV expansion. The empirical results show that MMDG accentuates midday net-load valleys, particularly on weekends, with the lowest values occurring on Sundays, approaching 50,000 MW, followed by evening recoveries exceeding 25,000 MW and extreme short-term ramp rates approaching 10,000 MW per hour. Flexibility Factor indicators range from 0.59 to 0.71, indicating heightened short-term operational stress. At the same time, ENE curtailment intensifies during hours of high distributed output, presenting moderate positive correlations (ρ ≈ 0.37–0.49, p < 0.01). Taken together, these findings demonstrate that the continued growth of MMDG amplifies intraday variability and curtailment exposure in Brazil's hydro-dominated system, thereby underscoring the need for strengthened coordination between transmission and distribution operators.