What California Is Learning from Solar Panels Built over Irrigation Canals

Project Nexus tests mounting solar panels above working irrigation canals in Turlock, California to capture electricity while shading water and reducing evaporation. Founded by Solar AquaGrid’s Jordan Harris and Robin Raj and built with Turlock Irrigation District, UC Merced and the Department of Water Resources, the pilot uses three designs - a wide-span canopy over a 115-foot canal, tilted panels over a 20-foot canal, and retractable low “accordion” panels - and is fully energized at 1.7 megawatts. Researchers instrument the site to measure temperature, humidity, wind, radiation and evaporation. UC Merced estimates that covering 100 miles of narrow canals would save enough water for 2,700 households and generate roughly 330 megawatts, while wide canals could save water for 11,000 households and produce up to about 1,400 megawatts per 100 miles. The project aligns with California’s push to expand solar as it pursues 100% clean electricity by 2045 amid growing evaporation losses projected to shrink water supply by up to 25% by 2050.

The pilot revealed co-benefits - reduced algal growth, improved water quality and faster siting compared with new ground-mounted solar - and kept natural land from being developed. It also exposed practical obstacles: complex stakeholder coordination across water, land and power authorities, high costs and logistics of connecting transmission, and varied maintenance needs that force different designs (Turlock’s panels sit high to allow mechanical canal cleaning). Urban canals that require frequent human access are unsuitable; some districts prefer piping canals instead. Funded largely by a $20 million state grant, the pilot demonstrates a promising, site-specific strategy for pairing water and clean energy while highlighting scalability challenges.