Floatovoltaics are a cool way to super-charge your solar panels with water

Originally published at: https://boingboing.net/2020/06/23/floatovoltaics-are-a-cool-way.html


Probably also prevents algae growth too, and breeding mosquitoes. A big plus.

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I was genuinely shocked at what a seemingly-obvious win-win scenario this was.

When something like that happens, the sensible thing to do is to ask, “What am I missing?”

In this case: (A) biofouling–only prevented at Las Tórtolas because the water is poisonous. (B) Maintenance costs. Water is corrosive, and anything that moves, breaks. The expected lifetime of those panels and all the wiring is going to be way below what you’d get on stable dry land.


I too worried about the maintenance. As for biofouling, they somehow manage to avoid it when using shade balls.


Those black balls are on top of treated water–full of chlorine. And even if they do grow a layer of slime, they still fulfill their primary purpose of being opaque. (They’re there to keep bromine from becoming bromate.)

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Those black balls aren’t wired together in series with copper wire. Photovoltaic panels need 100% electrical reliability to be useful as power generation devices. (It’s true that they will still stop evaporation if their wiring fails.)

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As an ecologist, I disagree.

Light plays an important role in water bodies. The whole chemistry might change if you cover enough of the surface. Not to speak of ecological networks.

Also, don’t be to sure about mosquitoes. There are different species, and some really, really prefer to have a smallish opening and the rest of the surface covered. That’s why, e.g., water barrels with a lid are often full of mosquito larvae of one species while the open pond beside contains none at all.


I also thought of the California reservoirs. Seems like preventing evaporation in reservoirs would be a big thing anywhere with frequent droughts.

(Being from Michigan I was pleasantly surprised to see that Southern California is not currently experiencing a drought. For a while there we thought you all were just going to dry up and blow away.)

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Fraunhofer Institute has been running a test of photovoltaics over aquaculture ponds, similar to the test they have been running with photovoltaics over farmland (you can shade crops by up to one third of the available sunlight without reducing production it seems). Here’s some information about it:


But it’s a great way of greenwashing a tailings pond.

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Boy do you guys get a lot of water.

I have worked in the solar industry for a few decades, in various capacities. I will not claim to be an expert on floating solar per se, but I am certainly no stranger to it. Floating solar can be a great win-win proposition, but it is definitely not as simple and straightforward as finding a body of water and putting some solar panels on it. (And I have to say I’m not familiar with any commercial-scale projects involving putting solar panels under water.) As at least one other commenter has noted, the biological impacts are not universally and automatically positive, and water that is covered by solar panels can generally not be used for other purposes, such as recreation or fishing – aquaculture excepted, though to my knowledge that is still very much an R&D topic that has yet to be commercially exploited.

As a practical matter, commercial applications of floating solar are by far the largest in Asia. This is mainly down to a combination of geography, regulation, and possibly culture, with more large population centers near suitable bodies of water. “Suitable” is not easy to define, but it has both technical and political aspects that vary from country to country.

Outside of Asia, the commercial potential has been widely regarded as limited, but that view is changing, little by little, almost daily. For example, a recent study that I cannot seem to locate at the moment indicated that Germany alone would have tremendous power-generation potential just from filling decommissioned strip mines and quarries with water and using them as combined recreation and solar farms. There is also a lot less opposition to such projects on ecological grounds, since artificial bodies of water created in a habitat that was destroyed decades ago have no pre-existing ecosystem to disturb.

That said, I personally expect that agri-photovoltaics will be more impactful. It is still a developing field, but early indications are that it is beneficial not just for energy and crop yields, but for biodiversity too.


Someone please clarify: I get why floatovoltaics may have beneficial (or detrimental) effects on the bodies of water they cover. But what power generation benefits do they offer over comparable solar arrays on dry land?

I also get why theoretically putting a solar array under water might offer benefits (increased focusing of the sun?), or maybe I’m wrong about that, too. But no one in the article or on the thread addressed the question of why it’s advantageous to put arrays floating on water vs on dry land.

Photovoltaics work better if they’re kept cool–tricky to accomplish, as they have to be dark-colored and out in bright sunlight. Putting them close to or in water can cool them.


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