Off-grid rural electrification faces significant challenges, including unreliable grid connections, high variability in renewable energy generation, and limited financial resources. In many regions, such as Sub-Saharan Africa, weakly-connected mini-grids present a promising solution; however, their operation is often constrained, if not undermined, by uncertainties in energy demand, renewable production, and frequent grid outages. Addressing these challenges requires advanced optimization techniques to ensure reliable, cost-effective energy access.

The Autarky model, developed in Julia, offers an innovative approach to optimizing the economic dispatch of renewable-powered, weakly-connected mini-grids under uncertainty. By integrating Joint Chance Constraints (JCC), the model ensures robust operation during outages and renewable variability while maintaining reliability at a predefined probability level. It addresses four key uncertainties: solar power forecasting errors, load demand forecasting errors, and the timing and duration of main grid outages. The model strategically schedules diesel generators and battery reserves to maximize operational efficiency and guarantee energy supply even during grid disruptions. Autarky is benchmarked against three alternative approaches — Individual Chance Constraints (ICC), an Expected-Value Model (EVM), and a Regular deterministic model — to evaluate the trade-offs between reliability and cost. The framework is validated through a real-world case study of a mini-grid in Lake Victoria, Tanzania. Results demonstrate that the JCC model achieves a 90% probability of successful islanding with 3-hour daily grid outages, significantly enhancing reliability compared to ICC (58%) and EVM (20%), while leading to a 25% reduction in profit.

Key contributions of this work include: • A stochastic optimization framework tailored for weakly-connected mini-grids, integrating multivariate Gaussian distributions through spherical-radial decomposition. • A comparative analysis of dispatch strategies, quantifying the trade-offs between cost and reliability across different models. • A practical case study using real-world data from Tanzania, validating the model's effectiveness in addressing uncertainties and improving energy access. By fostering open-source collaboration, Autarky aspires to accelerate the global deployment of resilient mini-grids, thereby contributing to universal clean energy access and the realization of the United Nations’ Sustainable Development Goal 7 (SDG-7).

The model is openly accessible on GitHub. Link: https://github.com/Autarky-Power/Minigrid-JCC/