Overcoming the Bottleneck of Unreliable Grids: Increasing Reliability of Household Supply with Decentralized Backup Systems

Abstract

Electrification efforts have long been a centralized, politicized and bureaucratic process heavily dependent on central grid extension. However, grid connection may not guarantee reliable supply and even grid-connected households can remain in lower tiers of electrification. By promoting the integration of solar home systems (SHS) in electrification plans, consumers could bridge blackout times and climb the ladder of electrification. To evaluate this potential, we perform a case study in Gauriganj district in Nepal based on primary survey data (2018), including real-time measurements of actual blackout occurrences. Offgridders, a self-coded open-source simulation tool based on the Open Energy Modelling Framework, is applied to determine the optimal grid-supporting capacities of multiple backup systems, including SHS and batteries. As a simplification, batteries are assumed to have a fixed lifetime of 5 years, while future fuel or electricity price changes are not considered. To compare the solutions, we propose the Effective Energy Supply Costs (EESC), calculated from the system’s annuity and supply reliability. For households of lower electricity demand (Tier 2) an SHS of approx. 10 Wp PV and 100 Wh battery powering a secondary DC circuit is the cheapest backup option at 21 €/a, supplying all daily demand not met by the grid. A household with higher electricity demand (Tier 4) is most cost-effectively served by a backup diesel generator, however the next cheapest solution is an SHS of approx. 40 Wp PV and 160 Wh battery, powering a secondary DC circuit during blackouts at 160 €/a. Encouraging investments in these decentralized renewable energy systems can support efforts towards achieving SDG7.