Enhancing solar mini-grid utilisation in farming communities: crop strategies to reduce costs and improve energy access

Abstract Approximately 80% of the global population without access to electricity live in sub-Saharan Africa (SSA) with rural areas disproportionately affected. Solar-powered mini-grids are being used to increase rural electrification. However, their deployment is hindered by high costs, low electricity demand, and limited incomes in rural households. Agriculture constitutes 70% of rural incomes in SSA and faces threats due to a reliance on rainfall coupled with low irrigation levels in the context of climate change. Irrigation loads have been suggested as a strategy to enhance the economic viability of solar mini-grids by boosting electricity demand: reducing the levelised cost of used electricity (LCUE) whilst improving farmer yields and incomes. This study investigates a case study in Tanzania, selected based on the amount of population without access to electricity, the potential for irrigation, and the prevalence of photovoltaic solutions in the least-cost pathways for rural electrification. The seasonality and timing of irrigation demand, as well as crop mixes, are varied to optimise for the lowest LCUE using the open-source modelling framework continuous lifetime optimisation of variable electricity resources. Evapo-transpiration and energy-system modelling are used to estimate energy demand. We find that adding irrigation loads has the potential to increase the LCUE and lower asset utilisation (load factor) when compared to residential loads but that, by selecting crops with longer growth periods, optimising irrigation timing, and implementing multiple planting seasons, the LCUE can be up to 7% less than residential-only systems with an increase seen in asset utilisation. LCUE values of 0.54–1.30 $/kWh were found: higher costs were associated with shorter crop-growth periods, single planting seasons, and poorly timed irrigation loads whilst lower costs were observed with bimodal cropping and solar-coordinated irrigation times. The research highlights that, when incorporating irrigation loads into rural-electrification strategies, specific factors should be considered to enhance their viability within mini-grids in SSA. We recommend to both policymakers and mini-grid developers to promote multiple planting seasons (bimodal cropping) and encourage optimal crop mixes where relevant alongside irrigation schemes and rural electrification projects as well as adopting the use of flexible tariffs for irrigation loads.