Surplus energy in solar home systems as driver for bottom-up grids: When grids emerge from the edge

In this paper, surplus energy (SE) from solar home systems (SHS) with energy storage is studied from the perspective of bottom-up grids. The paper addresses two central research questions: 1) How much SE do SHS generate depending on system size parameters and load metrics? and 2) Can SE provide the basis for bottom-up grids in rural swarm electrification? We first analyze different SE profiles for different stochastic demands from three households with various PV and battery system sizes. Next, we analyze how these SE profiles can be used to supply additional households with lower or equal demand. We find that the SE is highly dependent on PV size and cannot be significantly reduced by increasing battery size. Demand profiles with high Peak to Average Power Ratio (PAPR) and low Load at Day Time Ratio (LDTR) are shown to have the highest levels of SE. Simulations show that households with PV and battery system can supply several other households with its SE only. This study shows excellent potential for developing a framework model for bottom-up grids through SHS sizing and bottom-up planning of interconnections in rural communities.