Low-voltage, low-power solar photovoltaic (PV) based DC microgrids are becoming very popular in non-electrified regions of developing countries due to a) lower upfront costs compared to utility grid alternatives and b) limited power needs of rural occupants. The optimal planning of distribution architecture along with sizing of various system components such as solar panels, batteries and distribution conductors is essential for minimizing the system cost and enhance its utilization. In this work, we develop a framework for optimal planning and design of low-power low-voltage DC microgrids for minimum upfront cost. The analysis is based on a) region-specific irradiance and temperature profiles, b) constraints in storage and distributions, c) distribution loss analysis and d) optimum component sizing (storage, conductor and PV panel) requirements based upon an energy balance model for a 24-hr operation. We further analyze the merits of tailoring distribution architecture for maximizing the system utility in the planning of future microgrid deployments.

Solar photovoltaic (PV) direct current (DC) microgrids have gained significant popularity during the last decade for low cost and sustainable rural electrification. Various system architectures have been practically deployed, however, their assessment concerning system sizing, losses, and operational efficiency is not readily available in the literature. Therefore, in this research work, a mathematical framework for the comparative analysis of various architectures of solar photovoltaic-based DC microgrids for rural applications is presented. The compared architectures mainly include (a) central generation and central storage architecture, (b) central generation and distributed storage architecture, (c) distributed generation and central storage architecture, and (d) distributed generation and distributed storage architecture. Each architecture is evaluated for losses, including distribution losses and power electronic conversion losses, for typical power delivery from source end to the load end in the custom village settings. Newton–Raphson method modified for DC power flow was used for distribution loss analysis, while power electronic converter loss modeling along with the Matlab curve-fitting tool was used for the evaluation of power electronic losses. Based upon the loss analysis, a framework for DC microgrid components (PV and battery) sizing was presented and also applied to the various architectures under consideration. The case study results show that distributed generation and distributed storage architecture with typical usage diversity of 40% is the most feasible architecture from both system sizing and operational cost perspectives and is 13% more efficient from central generation and central storage architecture for a typical village of 40 houses. The presented framework and the analysis results will be useful in selecting an optimal DC microgrid architecture for future rural electrification implementations.