Solar on canals reduces water evaporation by 70% and algae growth by 85%(pv-magazine.com)
pv-magazine.com
Solar on canals reduces water evaporation by 70% and algae growth by 85%
https://www.pv-magazine.com/2026/05/04/solar-on-canals-reduces-water-evaporation-by-70-and-algae-growth-by-85/
22 comments
Reducing algae growth makes sense for canals. Would this be a desirable outcome if we were placing panels on, say, a body of water behind a dam (at a safe distance, and contained). Are there ecological impacts of reducing algae growth?
Depends on the use of the water body - as a reservoir for drinking water it would make sense [1], if you want the water for fishing not so much.
[1] https://www.sciencealert.com/here-s-what-s-really-going-on-w...
[1] https://www.sciencealert.com/here-s-what-s-really-going-on-w...
Ok... that makes sense.
Covering one the New Zealand's hydro dams in panels would produce same amount as hydro dam itself. Floating solar is somewhat easier to install as you don't need to drive piles, you let them float on (anchoring is needed tho). Round platforms can somewhat easily rotate to track sun. You already have most of grid there and you can curtail hydro when sun is out...
Instead we burn diesel and coal to preserve water levels for peak demand (it's actually not that simple, but still sounds dramatic).
Instead we burn diesel and coal to preserve water levels for peak demand (it's actually not that simple, but still sounds dramatic).
Why do we arch the panels over the water? I've heard some say they need to send boats down the canal for maintenance. Okay. But why not just have lower panels that can be lifted in case of trouble? They're less likely to get blown around by wind and that should make them cheaper to build. And they could reduce evaporation and algae even more.
I've been vaguely wondering lately:
The climate crisis is solar energy getting trapped on the planet instead of radiating into space.
Solar panels convert light to electricity to ultimately mostly heat, instead of reflecting it to space. So it also traps energy on our planet.
How big is the impact of this? Right now, it is probably ignorable, but will there be a theoretical point where solar itself becomes a climate crisis?
The climate crisis is solar energy getting trapped on the planet instead of radiating into space.
Solar panels convert light to electricity to ultimately mostly heat, instead of reflecting it to space. So it also traps energy on our planet.
How big is the impact of this? Right now, it is probably ignorable, but will there be a theoretical point where solar itself becomes a climate crisis?
Because of the reciprocity of absorption and emission: the panels which absorb more also proportionately radiate heat back into space at night more effectively than whatever they cover (which presumably has a higher albedo)
You might then wonder why the albedo of the poles matters (why are scientists concerned about that?). The answer to that is that the poles are very cold and black bodies radiate energy as T^4.
So you don’t want to have low albedo where it is cold and a high albedo where it is hot because then the most emissive surface isn’t emitting much heat due to low T and the places with high T have low emissivity. Obviously heat transport within the atmosphere is hugely important for this analysis, which you can’t easily approximate with napkin math.
However solar panels are most likely to be placed where it is relatively hot (because humans mostly don’t live at the poles). So that actually good because now you have more emissive surfaces with high T, which promotes global cooling.
You might then wonder why the albedo of the poles matters (why are scientists concerned about that?). The answer to that is that the poles are very cold and black bodies radiate energy as T^4.
So you don’t want to have low albedo where it is cold and a high albedo where it is hot because then the most emissive surface isn’t emitting much heat due to low T and the places with high T have low emissivity. Obviously heat transport within the atmosphere is hugely important for this analysis, which you can’t easily approximate with napkin math.
However solar panels are most likely to be placed where it is relatively hot (because humans mostly don’t live at the poles). So that actually good because now you have more emissive surfaces with high T, which promotes global cooling.
That's an impressively thorough answer to a vague wonder. Thanks
I remember reading a back-of-the-envelope guesstimate of just this phenomenon, and it did not amount to anything significant. It's about the change in albedo.
One more reason to put data centers in space...
Seems promising but it would have been nice to have some figures and the estimated cost at scale (or even just costs for the prototype).
> The Nexus project, a 1.6 MW solar installation on the canals of the Turlock Irrigation District (TID) in California, is now complete and operational. The $20 million state-funded pilot is presented as a model for agricultural regions affected by water stress.
It's the web, follow the links to related pages and you usually find more information.
It's the web, follow the links to related pages and you usually find more information.
Unfortunately I suspect this idea is somewhat dead-on-arrival… anti-renewable people will fight it for obvious reasons, while environmentalists will fight it due to concerns over shading the waterways.
What's the fallacy called where you oppose something based on the fact that it has impact on something, not realising that the alternative is is even worse?
I see people talk about how ugly solar panels make mountainsides, but when I ask "would you prefer a coal factory there instead?" nobody would.
I see people talk about how ugly solar panels make mountainsides, but when I ask "would you prefer a coal factory there instead?" nobody would.
That’s the nirvana fallacy. And it gets used VERY often against renewables.
Why would environmentalists be concerned about shading canals?
Because you’re changing something about the environment, and we can’t have that until it’s been studied to death.
The canal is already made of concrete, I think the environment might have been a little altered already.
They're concerned about nuclear so...
Isn’t this well known at this point? This 2020 article reports on solar installations on canals in Gujarat, India.
https://www.bbc.com/future/article/20200803-the-solar-canals...
https://www.bbc.com/future/article/20200803-the-solar-canals...
Nah, this is peak US innovation! /s