Technical performance of multiple mini-grids when integrated with the main grid distribution network

Abstract

This study investigates the technical performance of three solar based mini-grids integrated with the main grid distribution network in Uganda. Access to stable electricity is vital for socio-economic development, yet the national grid struggles to serve rural and island communities due to infrastructure and financial limitations. In such areas, mini-grids offer a practical solution for accelerating electrification. Three mini-grids—one in Kalangala and two in Bunjako Island—were modeled and simulated in DIgSILENT Power Factory, including both standalone operation and integration with the main grid. Scenarios evaluated included solar-only, gridonly, and hybrid configurations. Key technical metrics such as voltage regulation, power losses, and power factor were assessed under dynamic load and generation conditions. Standalone systems experienced voltage instability and poor power factor, especially during low demand or excess generation. Integration with the main grid significantly improved voltage profiles and power factor but introduced additional technical losses from long-distance power flows. Strategic installation of capacitor banks provided reactive power support, reducing current flows and line losses. The study concludes that coordinated operation of mini-grids with the main grid—supported by intelligent reactive power compensation—can enhance voltage stability, power quality, and overall system reliability. These findings offer practical guidance for decentralized electrification in similar Sub-Saharan African contexts.