KIU, Main Campus - A team of researchers from Kampala International University has developed a groundbreaking design and optimization framework for reliable off‑grid solar PV-battery mini‑grids, offering a practical solution to electrification challenges faced by rural trading centers across Uganda and Sub‑Saharan Africa.

The study, titled “Design and Optimization of Reliable Off‑Grid Solar PV–Battery Mini‑Grids for Trading Centers in Uganda,” was conducted by Mundu M. Mustafa, Mariam Basajja, Emmanuel Kweyu, J.I. Ssempewo, S.N. Nnamchi, and Daniel Ejim Uti. Their work provides a scientifically robust approach to sizing photovoltaic (PV) and battery storage systems under real‑world tropical conditions.

Addressing Rural Energy Gaps Through Smart Mini‑Grid Design

Rural trading centers are vital economic hubs, yet many remain underserved by national electricity grids. The researchers note that reliable electrification in these areas requires accurate PV‑battery sizing methods that account for seasonal variations, load behavior, and storage autonomy.

To address this, the study introduces a reliability‑constrained design framework based on hourly energy‑balance simulations using worst‑month solar conditions. This ensures that systems remain functional even during prolonged periods of low sunlight.

A representative trading‑center load profile of 132.1 kWh/day was used to evaluate six PV–battery configurations, combining lead‑acid and lithium‑ion storage technologies with autonomy durations of 2-4 days under conservative peak sun hour conditions of 4.0 – 4.5 hours/day.

Key Findings: Reliable, Cost‑Effective System Configurations

The study’s simulations produced system capacities ranging from:

• 40-48 kWp for photovoltaic generation
• 280-870 kWh for battery storage

These values varied depending on battery technology and autonomy duration.

State‑of‑charge simulations confirmed that all evaluated systems maintained stable operation above minimum thresholds, even during extended low‑irradiance periods. Reliability assessment using loss‑of‑load probability (LOLP) yielded values between 0.003 and 0.028 for prioritized loads – indicating high reliability across configurations.

A lifecycle economic evaluation using levelised cost of energy (LCOE) showed that lithium‑ion battery systems outperform lead‑acid alternatives, offering better reliability‑cost balance.

Among all scenarios, the researchers identified a three‑day lithium‑ion storage configuration – consisting of 42 kWp PV and 420 kWh battery capacity – as the most optimal solution for rural trading‑center electrification under worst‑month design conditions.

A Framework for Smarter Rural Electrification

The study provides a practical and scalable framework for engineers, policymakers, and energy developers working to expand rural electrification. By linking load characteristics, storage autonomy, and solar‑resource constraints, the framework ensures that off‑grid mini‑grids can deliver reliable power throughout the year.

The authors emphasize that this approach can significantly improve the design of mini‑grids across tropical regions, supporting economic growth, enhancing energy access, and strengthening resilience in underserved communities.

This research reinforces KIU’s commitment to advancing renewable energy innovation, sustainable development, and applied engineering solutions that address real‑world challenges in Uganda and beyond.