Why isn’t the CAP canal covered by solar panels?

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CAP Canal Image

We get these questions a lot: Why don’t you cover the 336-mile CAP canal with solar panels? That would be more efficient, producing more renewable supplies and helping to prevent evaporation, right?

Fair questions. Yet as enticing as the idea might be, studies have revealed many reasons why building such a solar covering would be a poor decision.

Here are a few:

  • Construction difficulties. It’s much more difficult to build a support structure that spans the canal than typical solar array systems that are built on the ground;
  • Sun-tracking technology. Solar arrays built to span over the canal system can’t be readily created to track the movement of the sun (and so would lose efficiencies);
  • Inefficient maintenance demands. We’d have to regularly remove the solar panels to inspect the concrete canal liner and other canal features for damage (this would be very costly and time consuming);
  • Geographical challenges. The CAP canal system runs through many remote areas that do not have electrical transmission systems nearby and building one to move the power from the solar arrays to the main points of use (at the pumping plants) is also very costly;
  • Prohibitive overall cost. The U.S. Bureau of Reclamation, which originally constructed CAP, has conducted studies of this possibility and also found the cost to be prohibitive. Covering the canal would have quadrupled the $4 billion the project originally cost.
  • Evaporation. Some believe putting solar panels over the canal would reduce evaporation and thus save a lot of water. But evaporation from the canal is actually minimal (less than 2 percent of CAP’s annual deliveries). Even if all of the evaporation from the canal was eliminated, it would not justify the expense of solar panel construction and the resulting operational challenges.

So at the end of the day, we found that a more cost-effective means for solar energy use is for CAP to enter into long-term power purchase agreements with solar facility operators to purchase the power developed by land-based solar facilities that are located near existing large power transmission lines.

Curious about CAP’s use of solar? See one of our recent projects.