What California is learning from solar panels built over irrigation canals
California’s experiment with installing solar panels over irrigation canals aims to both reduce water evaporation and generate clean electricity without consuming additional land. Commenters weigh the engineering and economic tradeoffs versus conventional ground-mounted solar, including structural costs, maintenance complexity, permitting hurdles, and the value of preserving cropland and sensitive desert ecosystems. The conversation also touches on precedents in India, concerns about materials, grid and pricing impacts, and how such hybrid water–energy projects fit into broader debates over California’s water use, infrastructure, and environmental policy.
Engineering & Economics of Canal Solar
- Many argue ground-mounted solar in fields is cheaper: simpler supports, easier access, standard hardware, shorter cable runs.
- Others counter that usable “empty land” in California is limited or contested (ag land, wildfire risk, NIMBY, national parks, desert wind/sand).
- Canal structures must handle large spans and strong winds; panels act as sails, driving heavy steel trusses and higher cost.
- Some think “cheap shade” fabrics would be better for evaporation alone; others note durability and wind loads mean shade structures wouldn’t actually be “cheap.”
- Several point out the permitting advantage: building on existing canal right‑of‑way is far faster than on new greenfield sites.
- Maintenance over water is seen by some as a big cost multiplier (boats, safety) and by others as a manageable, designable problem.
Water, Land Use, and Alternatives
- Primary stated benefit is reduced evaporation and better water quality (including less algae), with electricity as a bonus.
- Discussion about deeper causes: historical canal projects, water rights, loss of soil moisture and topsoil, and whether restoration/ecological projects would be a better long‑term fix.
- Alternatives raised: piping or tunneling canals, desalination (esp. brackish water), better rainwater capture, and reduced water use in agriculture and out‑of‑season food production.
- Agriculture is identified as the dominant water consumer; some note exports like alfalfa and nuts, not just local diets.
Embodied Energy, Materials, and Pollution
- Initial skepticism that the steel and panels might never “pay back” their embodied energy.
- Multiple back‑of‑the‑envelope calculations in the thread argue the array’s lifetime output easily exceeds the energy used to produce both steel and panels, especially with recycling.
- Solar panel recycling is discussed: most mass is glass and aluminum; doped silicon and silver are smaller but increasingly recoverable.
- Concern about panel chemicals leaching into canals is raised; others say risk is small compared to current pollution sources, and note studies showing net water quality improvements when replacing diesel generation. Humidity‑related reliability issues are flagged as a design concern, not a showstopper.
Policy, Grid, and Social Context
- California’s high share of zero‑carbon power (notably solar and batteries) is praised but also blamed by some for high prices; others attribute costs primarily to wildfire liability and grid upgrades.
- Fears about wealthier users going off‑grid and leaving poorer customers with rising grid costs surface.
- Vandalism and copper theft at remote solar sites are repeatedly mentioned; debate ensues over security guards vs. incarceration vs. drug policy and poverty as root causes.