12 votes

California's next energy experiment is happening above aqueducts, reducing evaporation and increasing solar panel efficiency

Posted by boxer_dogs_dance
Tags: energy.renewable, water, usa.ca, solar power, technology, infrastructure, solar panels, aqueducts, evaporation, efficiency, experiments, canals, future, author.tessa mclean, source.sfgate
https://www.sfgate.com/california/article/california-energy-experiment-solar-topped-canals-21045020.php

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Title
California's Central Valley waterways could look a lot different in the future
Authors
Tessa McLean
Published
Sep 16 2025
Word count
1000 words

6 comments

  1. [5]
    l_one
    Link
    While there are certain practical and maintenance-related challenges in this approach (construction and ongoing maintenance of solar at elevation above ground level (we've done this part with roof...

    While there are certain practical and maintenance-related challenges in this approach (construction and ongoing maintenance of solar at elevation above ground level (we've done this part with roof solar) and above a moving waterway (this part is somewhat new - drop a panel / parts / tool? may not get it back)) this makes logical sense to me and definitely has the feel of a natural, elegant improvement to resource management. I will be curious how much total energy is blocked from getting to the water as the solar panels will be hot and radiate a fair bit of IR/thermal - I'm certain it will reduce total energy absorption by the water though.

    While most of the rest of the US is headed to crappy cypberpunk dystopia, it's nice to see California implement some utopian elements.

    8 votes
    1. [2]
      papasquat
      Link Parent
      Yeah, makes a lot of sense to me. I'm always extremely skeptical of these types of "kills two birds with one stone!" type of solutions though. Usually when you're doing a large project, you're...

      Yeah, makes a lot of sense to me. I'm always extremely skeptical of these types of "kills two birds with one stone!" type of solutions though. Usually when you're doing a large project, you're optimizing for one thing (electricity production in the case of solar panels), while compromising a bit on that thing for a lot of other consideration which make that main objective possible. (How close are we to where we need that electricity? How do we maintain the panels? Is there a skilled workforce close enough to do this stuff? What's the land use like? How much risk is there from natural disaster/vandalism/theft? And of course, most of all, how much does this cost?). Optimizing for two main objectives (electricity production and evaporation reduction) exponentially increases the compromises you have to make.

      On the surface, this seems great, but we've been burned by extreme hype over seems great solutions in the past (anyone else remember "SOLAR FRICKIN ROADWAYS!")?

      4 votes
      1. l_one
        Link Parent
        Good ol' EEVBLog Dave! Yeah, solar roadways are idiotic as you have the harshest possible conditions applied. Solar canal covers do have some questionable aspects, but are orders of magnitude less...

        (anyone else remember "SOLAR FRICKIN ROADWAYS!")?

        Good ol' EEVBLog Dave! Yeah, solar roadways are idiotic as you have the harshest possible conditions applied. Solar canal covers do have some questionable aspects, but are orders of magnitude less problematic than trying to gather solar on a road. Still, it will remain to be seen if California would end up better served by just installing some form of sun-blocking roof / drape / any other heat-reducing covering over their canal system and separately making more traditional use of solar installations.

        I can see four broad categories of result:

        1. The system works and is at least minimally commercially viable in terms of costs vs resource gains when compared to a separated system of non-solar canal covers and traditional solar fields.
        2. The system works (in that it reduces water loss and generates electricity) but is clearly not commercially viable in that setting up System A and System B (non-solar covers and traditional solar fields) would achieve the same result better for less money - BUT in running the combined system we get the benefit of implementation R&D and advances that result from working through unique challenges, resulting in tangential benefits and gains.
        3. The system works (in that it reduces water loss and generates electricity) but is BOTH clearly not commercially viable in that setting up System A and System B would achieve the same result better for less money - AND no beneficial developments are gained.
        4. The system fails to achieve one (or both) goal(s) and provides no value on either axis compared to separate implementations.

        Solar roadways don't pass the sniff test.
        Solar canal covers don't fail the sanity check for me at first glance.

        5 votes
    2. [2]
      Englerdy
      Link Parent
      There seem to be a few factors that positively reinforce each other so there's a chance for a multiplicative benefit. Assuming a nominal efficiency of 20%, that's at a bare minimum 20% less solar...

      There seem to be a few factors that positively reinforce each other so there's a chance for a multiplicative benefit. Assuming a nominal efficiency of 20%, that's at a bare minimum 20% less solar heat reaching the water. But it'll be higher because the panels reflect a good portion of that radiation not absorbed. And the IR that they re-emit underneath from the heat will be substantially lower energy. And I'd bet the cool air above the water creates a bit of a breeze and keeps the panels much cooler. So without digging out a textbook I'd take a ball park guess at the panels reducing heat gain on the water between 50%-70%. The effects at play seem pretty substantial, but this is an off the head guess so that it for what it's worth.

      3 votes
      1. l_one
        Link Parent
        And solar panels are more efficient / produce more output when they are kept cooler. Definitely a positive, at least in theory.

        And I'd bet the cool air above the water creates a bit of a breeze and keeps the panels much cooler.

        And solar panels are more efficient / produce more output when they are kept cooler. Definitely a positive, at least in theory.

        5 votes
  2. boxer_dogs_dance
    Link
    I remember as a young girl asking why the aqueducts were not covered to reduce evaporation. I'm in favor of this development.

    I remember as a young girl asking why the aqueducts were not covered to reduce evaporation.

    I'm in favor of this development.

    4 votes