The concept of covering the CAP canal system with solar panels has been longstanding and arises frequently.

The basic idea is usually that a solar panel-covered CAP canal would prevent evaporation and generate renewable power supplies that could be used to move water through the system.

This opportunity has been studied a number of times during the past decades by the federal Bureau of Reclamation and CAP and the conclusions have been that building such a solar covering would be inefficient for several reasons.

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, so ground mounted solar array systems are less expensive.
• 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, when compared to ground mounted solar array systems).
• Inefficient maintenance demands. As part of our commitment to safety and integrity of the canal system, CAP would have to 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 is also very costly.
• 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 not significant, about 16,000 acre-feet of water per year. 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. Read more.

CAP has found new, more cost-effective opportunities to tap into solar energy, utilizing solar sites rather than covering the canal. This includes entering 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.

In addition, CAP is aware of some pilot projects that involve building solar array systems over canals, and additional studies in progress. We remain committed to understanding the results of these, as well as potential solutions that may change factors that currently make adding solar over the canal a challenge.

We hope this helps answer this interesting and popular question.