Irrigation as a system shaping load: technoeconomic and policy pathways for water energy food nexus

Journal article, 2026

Solar powered irrigation systems (SPIS) offer a pathway to expand agricultural water access while supporting national electrification objectives. This study develops a spatially explicit, temporally resolved planning and analysis framework that integrates hillside irrigation energy demand as a system shaping load within Rwanda's national electricity system. Two deployment pathways are assessed: behind-the-meter solar powered irrigation systems (BTM-SPIS) and grid-integrated solar powered irrigation systems (GI-SPIS). The Irrigation load profile is derived using elevation based pumping requirements and is coupled with hourly national economic dispatch model to evaluate grid interactions, system cost, and export tariff sensitivity across a range of photovoltaic deployment levels. Results show that GI-SPIS achieves the lowest system cost at early deployment stages because gravity storage can be charged using low cost off peak generation and irrigation schedules can be coordinated with national dispatch. BTM-SPIS becomes competitive only when photovoltaic capacity exceeds irrigation demand and surplus electricity is exported. At high photovoltaic penetration, surplus production exceeds 55 GWh yr-1, causing the marginal system value of exports to decline sharply, with export values falling to approximately 0.005 USD kWh-1. At moderate sizing levels, photovoltaic irrigation reduces annual system cost by displacing high-cost daytime thermal generation and flattening the net load profile. These findings demonstrate that surplus management, coordination mechanisms and tariff design rather than photovoltaic deployment alone are central to integrating solar irrigation into power-system planning. The results provide relevant planning evidence for aligning irrigation electrification with least cost generation expansion and export pricing strategies.