Wednesday, May 25, 2016


About time they hit the New York Times:

...floating solar arrays are becoming more popular, with installations already operating in Australia and the United States, and more planned or under construction.

The growing interest is driven in part by huge growth in the solar market in recent years as the cost of the technology has dropped quickly.

Floating solar arrays — they are often referred to as “floatovoltaics,” a term trademarked by one company — also have advantages over solar plants on land, their proponents say. Renting or buying land is more expensive, and there are fewer regulations for structures built on reservoirs, water treatment ponds and other bodies of water not used for recreation....The floating arrays have other assets. They help keep water from evaporating, making the technology attractive in drought-plagued areas, and restrict algae blooms. And they are more efficient than land-based panels, because water cools the panels.
The company attempting to trademark floatovoltaics can jump into one of those lakes, btw.

I tried to push this idea at my old water district five years ago and got nowhere, unfortunately. Now it's an idea whose time has come - in certain places, anyway. Maintenance is trickier, so any place with cheap land and lots of water will have no use for them. OTOH, the hot, water-short areas with expensive land, or problems from algae blooms, or problems from toxics like mercury that become much worse in warm, low-oxygen water are good candidates. All of which describe my water district. Now the local competitor for most-environmental water district has gone ahead with floatovoltaics, so maybe it'll spread.

I still think Lake Nasser behind Aswan Dam is a natural for floatovoltaics, although admittedly it's far from places with power demand. Dryer parts of India could also be great places, and they're experimenting with small systems already.


JohnMashey said...

Sonoma continues to impress.
For cyclists, try Tour d'Organics, with stops at local farms with some of the best juices ... and you see lots of solar panels on the rides.

Fernando Leanme said...

Building on water is more expensive, so is maintenance.

"The Flotosolar Ultra Generator, buy two and get one free, Labor Day special includes two pair of waders, mask and snorkel to help you retrieve tools that fall in the water. But wait, there's more, order now and you get a free copy of "The Tesla Story" by Elon Musk. Only $99999.99 at your nearest Solar City".

Arthur said...

This is an obvious thing to do to help save water in Lake Powell and Lake Mead - see this recent NY Times article which caused a bit of a stir:

Hank Roberts said...

I do like the idea.
Having solar panels cooled by water increases their efficiency.

I wonder how much this increases stratification, though.

On a site-by-site basis, it might be wise to divert a bit of electricity toward running an aquarium-type air pump and bubbler that could keep water somewhat oxygenated and circulating rather than trapping a cold layer under an excessively hot stagnant layer.

David B. Benson said...

Egypt has plenty of desert near population centers. No need for Lake Nasser.

meher engineer said...

The largest floating solar plant in the world is underway at the Yamakura Dam near Tokyo. The plant’s developer says it will generate enough electricity to power nearly 5,000 households, while offsetting more than 8,000 tons of carbon-dioxide emissions annually.(source:

meher engineer

Andrew said...

The Aswan Dam already produces c. 2MW of electricity, so I'd assume that the grid connection would be simple enough.

I've noticed the problem of panels overheating in the UK. Must be a serious problem inn places that are actually hot and sunny.


Soar heating of Lake Nasser has turned its organic bottom sediments into an efficient biomass methane generator

CH4 emission from the reservoir accounts for hald of Egypt's carbon footprint.

Brian should look more carefully at the capex of floaring PV 's- and press releases that fail to run the numbers- much does the gear for cooling panels sitting on rafts cost?

LA's floating reservoir ball stunt has proved an economic fisaco in terms of evaporation control.

Anonymous said...

LA's floating reservoir balls were never meant to be an evaporation measure; it was only because of the mayor's PR stunt that they were ever cast as such. They were installed because it turns out that when a large body of chlorinated water is exposed to the sun, whatever bromine is present can be photo-oxidized to bromate, which the EPA frowns upon in drinking water.

The reservoirs needed to be covered, and the ~$35 million for shade balls was cheaper than the ~$250 million it would cost to install a floating membrane. So in terms of their actual purpose, they were economically pretty reasonable. Any water savings were just a fringe benefit.

Brian said...

Cheap land + lots of freshwater = little need for floatovoltaics

Expensive land + little freshwater = much better case

Egypt's in between, I guess.

Maybe a rich, hot, water-poor country like Saudi would be better, especially for wastewater after treatment as part of recycling it for further use. And maybe Israel.


LOL, lolcat: LA invoked water conservation to extend the Silver lake ball float to five reservoirs , but having spent tens of millions to do so, has since removed them from , I believe, four.

The much ballyhooded water savings amounted to a few tens of acre feet saved at a cost three times higher than desalinization .

As our resident California water guru , could Brian please explain the rollback rationale ?

Hank Roberts said...

Bacterial overgrowth. No surprise there. Problem was they got the bacteria nature found handy, instead of anything intelligently designed, growing all over their plastic.

They drink that? Ew!

Hank Roberts said...

Or, dang, maybe it wasn't bacteria, it appears you can't trust the Internet these days:

Alternative explanations abound, including

"... they’re coming off the surface of all but one of the reservoirs. The shade balls will be removed not only at Ivanhoe Reservoir, which is being taken out of service, but also from Elysian and Upper Stone Canyon reservoirs. Instead, they’re receiving floating covers, says Richard Harasick, LADWP’s director of water operations.

Federal rules mandate that all bodies of drinking water open to the air be covered. Floating covers provide more of a complete barrier from both sunlight and airborne contaminants, says Harasick. The shade balls will only remain at Los Angeles Reservoir, and that’s because it would be cost-prohibitive -- to the tune of $250 million -- to install a floating cover on the 175-acre reservoir.... the 96 million plastic balls covering the surface have a lifespan of 10 years and require almost no maintenance aside from occasional rotation. In addition, Harasick adds, “we are experiencing cost savings in the reduced use of chlorine because the shade balls have reduced the amount of algae growth requiring treatment.” The LADWP also estimates they’ll see 300 million gallons in water savings with the shade balls...."

Anonymous said...

Can imagine those floats turned into the sun by a automatic winch, which would be a (comparatively) cheap way to enhance irradiation. If no elevation adaption is implemented (expensiv) this would make only sense in higer latitudes wich lower sun heights. ...


The LADWP also estimates they’ll see 300 million gallons in water savings with the shade balls...."

That's less than 100 acre-feet at 83 cents a gallon , -- no wonder the new LA minimum wage is 18 almonds an hour !