Solar home systems and swarm electrification: Decentralized power systems for energy access

Abstract

There is an urgency of achieving Sustainable Development Goal 7, which aims to ensure access to affordable, reliable, sustainable, and modern energy for all by 2030. Despite progress, 685 million people still lacked electricity in 2022, with the majority living in rural areas. Traditional rural electrification approaches, apart from grid extension, focused on static solutions such as solar home systems and microgrids and often overlook the dynamic nature of energy access needs. Swarm electrification, a decentralized approach inspired by swarm intelligence, proposes a dynamic and modular bottom-up strategy. The core principle is sharing surplus energy from solar home systems among neighbors and neighboring systems, forming interconnected local grids. The concept originated in rural electrification, but presents intriguing possibilities for unconventional settings such as Norwegian cottage fields. Many studies have identified surplus energy in solar home systems, but there is a lack of research analyzing what factors drive the amount of surplus energy and whether it is suitable for supplying other demands. This research gap is addressed through an open-source multi-model-based simulation and statistical analysis of solar home systems, incorporating experience and data from field work. Few studies have had a detailed focus on the early phase of swarm electrification. This thesis addresses this gap through a techno-economic study, analyzing the impacts of initiating swarm electrification on early participants in the Sub-Saharan context. Although the overall benefits of swarm electrification in later phases of the concept are presented in literature, there is a lack of studies showing how different energy sharing strategies impact the individual participants and the total community. In this thesis, such different sharing strategies are modeled and simulated for Bolivian, Kenyan and Norwegian cases, with an in-depth analysis of battery control setpoints in the Bolivian case, followed by a discussion based on energy justice. Norwegian cabins are evolving from simple shelters to energy-intensive homes facing sustainability challenges with increasing electricity consumption. Swarm electrification and energy sharing from individual off-grid solar home system at cabins is promising but challenging due to local conditions. An experimental setup with various PV panel orientations is used to measure PV power output over a three-year period (2021–2023) including observations of snow coverage. The results are integrated into the modeling and simulation of swarm electrification to improve accuracy, enhance realism, and determine the necessary level of detail for modeling the Norwegian context. This research finds key factors influencing surplus energy in solar home sys tems, such as PV and battery capacity and load characteristics. Surplus energy amounts increase with increasing PV capacity, however it does not decrease with increasing battery capacity once daily storage demands are met. Below that limit load characteristics influence the amount of surplus energy. The research reveals that surplus energy is not always present, especially for systems with lower PV and higher battery capacity. This work demonstrates how energy sharing in swarm electrification is heavily dependent on energy sharing strategies and control settings. If not designed properly, it can reduce energy access for some households. Comparative studies between Kenyan and Norwegian cases illustrate this effect and emphasize the impact of seasonal PV variations on the effectiveness of energy sharing. A study in rural Bolivia underscores the importance of equitable energy distribution and community participation in swarm electrification and shaping of energy sharing strategies. While Norwegian cabins face limitations during winter due to reduced sunlight, the variations in their load profiles offer opportunities for effective energy sharing. Although these variations are the dominant factor in beneficial energy sharing, this research highlights the advantages of accurate modeling of PV systems, particularly incorporating PV panel orientations to better understand the true potential of energy sharing. Simulated Norwegian cabin fields, using realistic PV input data, demonstrate remarkable potential to improve electricity access only through solar PV within the framework of swarm electrification. This research included the preparation of substantial groundwork for swarm electrification. Overall, the findings of this thesis support the scalability of swarm electrification principles in various contexts, advocating tailored approaches that take advantage of local conditions to maximize energy access benefits.