It seems like it would be more effective to simply put all the solar panels in a field, and construct a cheap shade over the entire canal no? The supports in the picture are massive and don't look cheap. Also I would imagine the solar array uses more copper than a similar capacity array just built in a field. You can't daisy chain multiple miles of solar panels together, so you need an extra power line to run alongside the whole thing.
Put the solar panels in a field: The solar array uses less copper.
The shade supports don't have to hold up solar panels: Shade supports cost less.
The best reasoning they give is that California has insane permitting requirements, and it takes 1/6 the time to build on developed land compared to undeveloped land.
Anecdotally speaking, I have heard of a massive California solar farm in an undeveloped area that has serious vandalism problems. Junkies will find ways through the fencing at night, strip copper and other materials from panels, and cause thousands in damages and lost energy just to extract enough scrap for a fix.
Nothing short of a face-to-face security response will deter these criminals, so there it is a challenging cost-benefit balance. At least panels in parking lots and other developed spaces have the benefit of witnesses. I'm sure a 20 foot climb up a steel beam over running water is a decent deterrent as well.
> It seems like it would be more effective to simply put all the solar panels in a field, and construct a cheap shade over the entire canal no?
No because now you're using land that could be used for other things, which is exactly what this avoids. This takes existing land that loses water and costs money, and makes it lose less water and make money.
My understanding is that "The best reasoning they give" is the entire point. It such a huge issue that it drowns out all of the valid but smaller issues you are pointing out. And, the benefit to the water is just a bonus.
The cost of building that steel structure that will hold up against maximum in 100 year wind forces isn't cheap. Large PV panels make very good sails. The trusses look basically the same as you'd see in a large agricultural barn, horse riding arena, etc. Putting the PV panels on empty bare land at a height people can walk around and work with would be considerably less costly.
I would very much like to see a total dollar figure for the example "roof trusses over the canel" structure vs. how many panels it can hold.
It's already true that the ground mounting costs and labor to assemble the ground mount are a huge part of building a large scale PV system.
> Putting the PV panels on empty bare land at a height people can walk around and work with would be considerably less costly.
What empty, bare land?
If its really empty and bare, there is a reason for it and that reason is probably a problem for building and maintaining PV, and otherwise you have to add the loss of the alternative uses of the land to the cost.
What's the lifetime of a "cheap shade"? And the cost to renew it over the same lifetime? And the cost of paying for other land?
... likely less than the ~$13/W this cost to install, but that included NRE for three different styles of panel mounting. Standardizing would cut costs significantly.
Yes, I'd like to see the "cheap shade" that could span as far as shown in the pics as well as survive strong gales. It wouldn't be like a cheap shade in your back yard.
I'm sure it could be done, but it would cost a fortune. My understanding is the canals were built to distribute water to farmers, and conservation/evaporation wasn't really much of a consideration because California had plenty of water back then.
BTW, I used to swim in those same canals around Modesto and Turlock as a kid. So gross.
I seriously doubt that you can chain even 1/4 mile of panels together without destroying things. Thats already puting thousands of volts and hundreds or thousands of amps through the silicon. If you are making it all parallel you still need wiring between panels that can handle that. The cabling doesn't go away, it just moves.
Wouldn't there still be supports in a feild of solar panels? Are you sure that those supports + the supports for the shade material are going to be less material than the supports for this?
Most shade material wears out pretty quickly. Will their replacement result in more expense, more waste, etc than just putting the solar panels?
Shade material is generally pretty heavy, is it really going to need significantly less robust support? Weight aside, how much of the load those supports are rated for is due to the actual weight of the panels, and how much is for forces from things like wind?
"Thats already puting thousands of volts and hundreds or thousands of amps through the silicon."
In a typical string of solar panels design, you'll get tons of volts but not a lot in amps - current cell maximums top out at ~11A and the connective MC4 wiring can't handle too much more current than that, so what you end up with is like a 1,000V 10A string on one MPPT connection into the inverter.
A solar panel is 4 feet or so on the long side. Theres 250+ of them in a string 1/4 mile long.... at 48 V/panel, you get to 12KV. even if it's topped out at 10A thats still 120KW... you need a hefty cable to carry that panel to panel. Which is the core of the point I was making.
Amps determine how hefty a cable needs to be, not volts. Volts mostly determine how thick the insulation needs to be.
14 gauge wire is basically all you need to carry 10A safely for an extended period of time regardless the voltage. It doesn't matter that you are carrying 120KW.
The proof of this is in EV charge cables. Those bad boys can carry up to 350kW. Yet the cables are often thinner than you might expect. How do they do this? It's by using high voltages (around 900V) which cuts back the amps to around 300->400.
Tesla's chargers peak (or used to) around 600V which has required them to have much beefier cables to handle the high current.
There are solutions like this to most of Californias big intractable problems, and they're not done because some California laws and/or regulations make it impossible.
This is one reason I now live in Nevada, where pretty much everything is legal...
When you read lines like "California’s extensive network of canals and aqueducts is the lifeblood of the state, providing clean water to populous cities and expansive farms that wouldn’t otherwise have it." you have to ask how we ended up with these canal systems, what the tradeoffs are in a landscape setup this way rather than one where water infiltrates the ground and stays hydrated, and who owns water rights in California.
(note: I'm not trying to totally bash the solar panel project nor some of the key figures involved who've done great work like Dustin Mulvaney, but do think we should think about how we ended up here)
I thought this was a pretty awesome video to provide the lore on how water got to Southern California. Growing up in Pasadena I heard the name Mulholland and Eaton (as in canyon) all the time but never realized they were so instrumental in the founding of the city and all the wild shenanigans that went into getting the water from up north to LA.
In searching YouTube history for it, I see I also stumbled across this project too: Why Aqueduct Solar Solves 2 MASSIVE Problems https://youtu.be/EVBacmPfQ6E (about 9 minutes in it gets into the engineering challenges mentioned else comment about wind loads and such).
oof, that is a crap ton of steel. I doubt those panels will ever harvest enough energy to offset the energy use to produce both the cells and supports.
I imagine with cells in that configuration, lifting wind loads are significant which is why it's overbuilt like that.
Perhaps some laminate timber for the cross supports?
Lastly, the US has got to start eating seasonally. The water problem in the southwest is all agriculture: people want to grow baby spinach in January. Unless we figure out a way to create a crap ton of energy cheaply so we can supply industrial sized flows without worrying about the energy cost, we use far more water than we should in California and Arizona.
Electricity is incidental (and a nice benefit) to the goal of "reduce evaporation of water from the irrigation canal and improve water quality".
> The duo went on to start Solar Aquagrid, an advocacy firm dedicated to reimagining aging canals, and partnered with the Turlock Irrigation District, UC Merced and the California Department of Water Resources to cover small sections of Turlock’s canals with solar panels. The new “solar canal” provides shade to limit evaporation and generates power all in one neat package. They call it Project Nexus, and it operates at the intersection of the state’s need for clean water and energy.
> ...
> But the canal site hosts more than just panels. Bales said they “have instruments out there to measure temperature, relative humidity, wind speed, incoming radiation, outgoing radiation, and a prototype instrument to measure evaporation directly.”
> When it comes to algae, the panels helped. “Last year when we drained the canal at the end of the irrigation season, there was a physical line on the sun side of the canal that had algae growth and then not algae growth from where the shade was,” Weimer said.
That it's green energy and can help supply the power demand is a bonus.
Steel takes about 4.750 kw-hours to produce per kg.[1]
A 450W solar panel will make roughly 562 kwh a year in California.[2]
So one panel running for one year offsets 140kg of steel production, roughly.
Thats an I-beam based structure so it's weight efficient and a heck of a lot more then 1 solar panel are going to fit on it.
Judging from a local steel supplier[3] and some span tables it looks like you'd need about a 360mm or so I-beam to bridge a 115 ft (30m) channel (the structure looks more efficient then that though) so call it 50kg per meter. So one span is probably ballpark 1500kg of steel.
A 450W solar panel is about 0.7m wide, the structure is fully covered so call it 42 panels per span offsetting the energy production of a little over 5900kg of steel per year (and it doesn't look like we're putting one solid I-beam per row of solar panels either since I see lightweight spanning channel in there).
According to my searches, steel production is something like 6-8 MWh/ton to extract, refine, and shape. A solar panel lasts 25 years at up to 80% effiency. This thing produces 1.7MW at peak. so call it 3 MWh/day average to account for a lot of adverse conditions over the lifetime. Thats 27000 MWh... so unless we are looking at more than 3000 tons of steel (we aren't) the steel production is accounted for. A panel takes something like 1.9 MWh equivalent in energy.... and again we aren't looking at 13K solar panels in this pilot.
So yes, in fact this does generate far more energy than goes into its production.
What bothers me the most as a consumer is the fact that this is paid for with a grant, yet my daytime energy rates are still more expensive than at night. Combined with the fact that PG&E will pay me 1/4 for feeding the same kWH back into the grid on top of a cost-of-service fee, it sours my view of projects like this.
Put the solar panels in a field: The solar array uses less copper. The shade supports don't have to hold up solar panels: Shade supports cost less.
The best reasoning they give is that California has insane permitting requirements, and it takes 1/6 the time to build on developed land compared to undeveloped land.
Nothing short of a face-to-face security response will deter these criminals, so there it is a challenging cost-benefit balance. At least panels in parking lots and other developed spaces have the benefit of witnesses. I'm sure a 20 foot climb up a steel beam over running water is a decent deterrent as well.
No because now you're using land that could be used for other things, which is exactly what this avoids. This takes existing land that loses water and costs money, and makes it lose less water and make money.
I would very much like to see a total dollar figure for the example "roof trusses over the canel" structure vs. how many panels it can hold.
It's already true that the ground mounting costs and labor to assemble the ground mount are a huge part of building a large scale PV system.
What empty, bare land?
If its really empty and bare, there is a reason for it and that reason is probably a problem for building and maintaining PV, and otherwise you have to add the loss of the alternative uses of the land to the cost.
Have you been to Death Valley, my friend? All of Southeastern California is empty, barren land. Death Valley, Mojave Desert, etc.
... likely less than the ~$13/W this cost to install, but that included NRE for three different styles of panel mounting. Standardizing would cut costs significantly.
BTW, I used to swim in those same canals around Modesto and Turlock as a kid. So gross.
I seriously doubt that you can chain even 1/4 mile of panels together without destroying things. Thats already puting thousands of volts and hundreds or thousands of amps through the silicon. If you are making it all parallel you still need wiring between panels that can handle that. The cabling doesn't go away, it just moves.
Wouldn't there still be supports in a feild of solar panels? Are you sure that those supports + the supports for the shade material are going to be less material than the supports for this?
Most shade material wears out pretty quickly. Will their replacement result in more expense, more waste, etc than just putting the solar panels?
Shade material is generally pretty heavy, is it really going to need significantly less robust support? Weight aside, how much of the load those supports are rated for is due to the actual weight of the panels, and how much is for forces from things like wind?
In a typical string of solar panels design, you'll get tons of volts but not a lot in amps - current cell maximums top out at ~11A and the connective MC4 wiring can't handle too much more current than that, so what you end up with is like a 1,000V 10A string on one MPPT connection into the inverter.
14 gauge wire is basically all you need to carry 10A safely for an extended period of time regardless the voltage. It doesn't matter that you are carrying 120KW.
The proof of this is in EV charge cables. Those bad boys can carry up to 350kW. Yet the cables are often thinner than you might expect. How do they do this? It's by using high voltages (around 900V) which cuts back the amps to around 300->400.
Tesla's chargers peak (or used to) around 600V which has required them to have much beefier cables to handle the high current.
This is one reason I now live in Nevada, where pretty much everything is legal...
[1] https://www.autonocion.com/us/arizona-solar-panels-irrigatio...
Build Soil has some interesting threads on this:
- https://bsky.app/profile/buildsoil.bsky.social/post/3lmeddjd...
- https://bsky.app/profile/buildsoil.bsky.social/post/3mkzybkk...
(note: I'm not trying to totally bash the solar panel project nor some of the key figures involved who've done great work like Dustin Mulvaney, but do think we should think about how we ended up here)
https://www.youtube.com/watch?v=x-RGL15Skuo
In searching YouTube history for it, I see I also stumbled across this project too: Why Aqueduct Solar Solves 2 MASSIVE Problems https://youtu.be/EVBacmPfQ6E (about 9 minutes in it gets into the engineering challenges mentioned else comment about wind loads and such).
I imagine with cells in that configuration, lifting wind loads are significant which is why it's overbuilt like that.
Perhaps some laminate timber for the cross supports?
Lastly, the US has got to start eating seasonally. The water problem in the southwest is all agriculture: people want to grow baby spinach in January. Unless we figure out a way to create a crap ton of energy cheaply so we can supply industrial sized flows without worrying about the energy cost, we use far more water than we should in California and Arizona.
Fair. But the almonds and alfalfa would like a word, especially since the alfalfa is shipped around the world for others to consume in some way.
So while it's definitely agriculture as a serious source, it's not just the US as the driver of that source.
> The duo went on to start Solar Aquagrid, an advocacy firm dedicated to reimagining aging canals, and partnered with the Turlock Irrigation District, UC Merced and the California Department of Water Resources to cover small sections of Turlock’s canals with solar panels. The new “solar canal” provides shade to limit evaporation and generates power all in one neat package. They call it Project Nexus, and it operates at the intersection of the state’s need for clean water and energy.
> ...
> But the canal site hosts more than just panels. Bales said they “have instruments out there to measure temperature, relative humidity, wind speed, incoming radiation, outgoing radiation, and a prototype instrument to measure evaporation directly.”
> When it comes to algae, the panels helped. “Last year when we drained the canal at the end of the irrigation season, there was a physical line on the sun side of the canal that had algae growth and then not algae growth from where the shade was,” Weimer said.
That it's green energy and can help supply the power demand is a bonus.
A 450W solar panel will make roughly 562 kwh a year in California.[2]
So one panel running for one year offsets 140kg of steel production, roughly.
Thats an I-beam based structure so it's weight efficient and a heck of a lot more then 1 solar panel are going to fit on it.
Judging from a local steel supplier[3] and some span tables it looks like you'd need about a 360mm or so I-beam to bridge a 115 ft (30m) channel (the structure looks more efficient then that though) so call it 50kg per meter. So one span is probably ballpark 1500kg of steel.
A 450W solar panel is about 0.7m wide, the structure is fully covered so call it 42 panels per span offsetting the energy production of a little over 5900kg of steel per year (and it doesn't look like we're putting one solid I-beam per row of solar panels either since I see lightweight spanning channel in there).
[1] https://solar.lowtechmagazine.com/2009/06/how-much-energy-do...
[2] https://www.cahomesolar.com/feeds/blog/solar-panel-energy-pr...
[3] https://www.mascotsteel.com.au/wp-content/uploads/2018/10/st...
While I agree those steel supports are large, that seems insanely wrong to me, but not an expert so curious if someone with more info could comment.
So yes, in fact this does generate far more energy than goes into its production.
Anyone know how this supposedly makes sense?