Canal solar in Arizona proves costly and limited

Estimated reading time: 6 minutes · Last updated: 2026-08-14

Canal solar arrived in the United States with a 2,556-panel, 1.31 megawatt installation that sits on steel trusses above 2,782 linear feet of the Casa Blanca Canal on Gila River Indian Community land. The array, funded with $5.65 million from the Inflation Reduction Act and expected to produce at least 2.26 million kilowatt-hours a year, reached first power on October 3, 2024. Engineers say the design keeps supports out of the water while shading it to reduce evaporation; David H. DeJong of the Pima-Maricopa Irrigation Project estimates evaporation could fall about 50 percent. As first reported by Autonocion.com.

It was scheduled to be the first in the Western Hemisphere, but our Phase 2 Casa Blanca Solar over Canal project actually was completed first.

David H. DeJong, director, Pima-Maricopa Irrigation Project

What Arizona built, who paid for it and why it matters

The Casa Blanca Canal installation covers 2,782 linear feet of the irrigation channel and carries 2,556 photovoltaic panels with a 1.31 megawatt nameplate capacity. The Bureau of Reclamation administered a $5.65 million Inflation Reduction Act grant for the project and expects at least 2.26 million kilowatt-hours annually from the array, a figure that Gila River Indian Community planners use to offset pumping power demand.

The local scale matters: the Pima-Maricopa Irrigation Project spends about $3 million a year to move 27 million kilowatt-hours of water, and David H. DeJong, who directs that irrigation project, says Casa Blanca will supply roughly eight percent of that load. The installation therefore functions as both a narrow demonstration of canal-mounted generation and a partial local load hedge, not as a broad solution to Colorado River shortages.

How the structure works and why it avoids the water

Tectonicus founder Ben Lepley designed a prefabricated steel truss that spans the canal without placing supports in the channel, keeping flow and maintenance access clear. The modular truss is built in blocks that tie into the local distribution grid roughly every 1,000 feet — about every megawatt — which simplifies electrical interconnection and explains why the Phase I Corps block is about 1,000 feet and 1.0 MW.

Keeping the structure out of the water raises costs but preserves canal function. Lepley described the design as deliberately modular so assemblies can be repeated, and the modular grid-tie spacing is the mechanical reason both projects use roughly megawatt-scale blocks rather than a single continuous feed.

Why canal solar costs more than ground arrays

Ben Lepley and other engineers say capital costs for canal-mounted solar run roughly twice those of ground-mounted systems because of the steel trusses and heavier foundations needed when you cannot place driven piles in the canal bed. Casa Blanca’s $5.65 million budget equals about $4.31 million per megawatt; the Army Corps’ I-10 Level Top Phase I was budgeted at $6.7 million for 1.0 megawatt, or $6.7 million per megawatt.

The Corps project also carried first-of-its-kind federal contracting conditions. Robert Savage, project manager for the U.S. Army Corps of Engineers Los Angeles District, said the district sought a tribally owned contractor and awarded the work to Numunu, a Comanche Nation-owned company; that federal process, DeJong wrote, is “very methodical,” and that methodical approach raised both schedule and cost relative to the Reclamation-funded Phase II.

Measured water savings, the evidence gap and policy context

Project operators have framed canal solar as a way to reduce evaporation while keeping panels cooler over water. DeJong has estimated Casa Blanca will conserve about 8 to 12 acre-feet of water a year; he has also put expected evaporation reduction at roughly 50 percent. An acre-foot equals about 325,851 gallons, so the savings amount to only a few acres’ annual irrigation — useful locally but far from river-scale.

The Interior Department required a five-year monitoring period for the Reclamation grant, and that study began with the array in October 2024, so a defensible season-long dataset will arrive near the end of the decade. Policy and funding are narrow: the Inflation Reduction Act set aside $25 million total for solar-over-water conveyance projects and Casa Blanca took $5.65 million of it, and on March 4, 2026 the Arizona Corporation Commission voted to repeal the Renewable Energy Standard and Tariff rules that had applied statewide to regulated utilities, although REST never governed the tribal utility.

How this could scale — the case for and against

The bottom line

Arizona’s Casa Blanca canal solar array proves the technical concept: prefabricated trusses can carry panels above a working irrigation canal without obstructing flow, and the system can deliver measurable local generation and some evaporation reduction. The barriers are clear and mechanical — capital costs roughly double ground-mounted arrays and federally mandated contracting or permitting paths can raise price and slow delivery. The outcome to watch is the five-year, instrumented monitoring that began with first power on October 3, 2024; those results will determine whether canal solar scales beyond isolated tribal and pilot deployments or remains an expensive niche for constrained sites.

What to watch

• October 2029 — end of the five-year monitoring period that began with the Casa Blanca array on October 3, 2024, when season-long evaporation and output data should be available.
• December 11, 2025 — public follow-up from the I-10 Level Top Phase I ribbon-cutting to compare cost, schedule and contractor outcomes against Casa Blanca.
• Early 2026 — whether the Gila River Indian Community’s self-funded Santan Canal array and the planned floating reservoir installation are energized and publicly reported.