Solar power development over canals is an emerging response to the energy–water–food nexus that can result in multiple benefits for water and energy infrastructure. Case studies of over-canal solar photovoltaic arrays have demonstrated enhanced photovoltaic performance due to the cooler microclimate next to the canal. In addition, shade from the photovoltaic panels has been shown to mitigate evaporation and potentially mitigate aquatic weed growth. However, the evaporation savings and financial co-benefits have not been quantified across major canal systems. Here we use regional hydrologic and techno-economic simulations of solar photovoltaic panels covering California’s 6,350 km canal network, which is the world’s largest conveyance system and covers a wide range of climates, insolation rates and water costs. We find that over-canal solar could reduce annual evaporation by an average of 39 ± 12 thousand m³ per km of canal. Furthermore, the financial benefits from shading the canals outweigh the added costs of the cable-support structures required to span the canals. The net present value of over-canal solar exceeds conventional overground solar by 20–50%, challenging the convention of leaving canals uncovered and calling into question our understanding of the most economic locations for solar power.

运河上的太阳能开发是对能源，水，食物关系的一种新兴回应，这种关系可能给水和能源基础设施带来多重好处。运河旁的太阳能光伏阵列的案例研究表明，由于运河旁较凉的微气候，光伏性能得到了增强。另外，已经显示出来自光伏面板的阴影减轻了蒸发并且潜在地减轻了水生杂草的生长。但是，尚未对主要运河系统中的蒸发节省量和财务共同收益进行量化。在这里，我们使用覆盖加利福尼亚州6,350公里运河网的太阳能光伏板的区域水文和技术经济模拟，该运河网是世界上最大的输送系统，涵盖了广泛的气候，日照率和水费。每公里运河³条。此外，遮蔽运河的经济利益超过横跨运河所需的电缆支撑结构的增加成本。超运河太阳能的净现值比传统的地下太阳能高出20％至50％，这挑战了保持运河畅通无阻的传统，并质疑我们对最经济的太阳能发电地点的理解。