[HN Gopher] A 100MW solar farm in Texas will mount panels direct...
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A 100MW solar farm in Texas will mount panels directly on the
ground
Author : orangebanana1
Score : 62 points
Date : 2022-12-09 21:33 UTC (1 hours ago)
(HTM) web link (www.canarymedia.com)
(TXT) w3m dump (www.canarymedia.com)
| rootusrootus wrote:
| Interesting idea. I've been toying with the idea of doing a
| ground mount install at home, but maybe I should try this instead
| to get more density. I love toys...
| melony wrote:
| I do not believe their claimed savings. Steel is a very cheap
| building material and at the scale of solar farms, the cost
| should be very low. (As an alternative to stainless steel on the
| other hand, it may make more sense)
| mycall wrote:
| > "Install in half the cost, half the time on 33% of the land"
|
| If the panels don't point directly at the sun, then you lose much
| of the efficiency.
|
| I wonder how the robot cleaner handles bird poop.
| Hermitude wrote:
| Horizontal panels also collect dust, so they still need to be
| propping them on the north side.
| avip wrote:
| All panels collect dust, but this setup is much more
| challenging to clean (and to generally service, i.e to
| replace a faulty panel)
| nimos wrote:
| This seems much easier to clean? A gigantic flat slab is
| pretty easy to automate something vs disconnected racks.
| avip wrote:
| (Modern utility scale PV installations are already using
| automated cleaning solutions).
|
| It is much better from POV of the cleaning robot
| maneuvering requirements. It's also much better in terms
| of single robot can access the entire installation.
|
| But it's worse in terms of how much distance the dust
| should be pushed before it's off panel (as I don't see
| any gaps there)
| s1artibartfast wrote:
| Service trade-off seems pretty marginal. They say the
| panels aren't tied down to the ground in any way, so you
| might be able to just pick one up and disconnect it
| elihu wrote:
| They have a robot that cleans the panels. It's a big, flat
| surface so they don't really need anything much more
| advanced than a Roomba.
|
| Apparently they also have special shoes that maintenance
| people can wear that distribute the weight properly so they
| can walk on them if they have to.
| gleenn wrote:
| They don't look propped at all in the photos. Also I think
| propping would be hard for the cleaning robot as it looks
| like is a super simple little robot with small wheels and
| just rolls straightened over them.
| constantlm wrote:
| Sounds like they're pretty confident this isn't an issue:
|
| >Our fees are based on the plant producing at its optimal
| performance. If the plant underperforms for any reason, we
| curtail our fees - creating strong incentive and perfect
| alignment with the long-term asset owner.
| s1artibartfast wrote:
| It all comes down to the economic tradeoffs. Panels are cheap
| and everything else is expensive.
|
| If you can get 75% efficiency for half the cost, your return on
| investment is 50% higher
| nine_k wrote:
| Panels may be cheap, maintenance / replacement is less so,
| because humans at work.
| theptip wrote:
| They use a robot for regular cleaning; looks like the
| design will make that cheaper too as it's basically a fancy
| Roomba.
| bilsbie wrote:
| We'll the cost isn't just the racks
|
| You've got to deal with permits for the structures. Installation.
| And then you have to do lawn trimming around all the racks. This
| can save on all of that.
| felgueres wrote:
| The reason they are tilted is to maximize irradiance hitting the
| panel. At a 0 degree angle (flat on the ground) you get a a lot
| around noon and then very little.
|
| This approach surely reduces land usage but what is the output
| per acre?
|
| I'd be really surprised if it's higher than with tilted modules.
| celtain wrote:
| I expect that they are getting lower output per acre, but in
| places where land is cheap and as solar panels continue to get
| cheaper, the money saved on building the support structures
| could be worth those losses.
| nimos wrote:
| Texas is pretty far south. If you use
| https://pvwatts.nrel.gov/pvwatts.php there is about a 9%
| increase in total output over the year for optimal tilt(27 vs
| 0) but then you also need to space modules.
|
| There is hourly data if you are interested but even Jan 1 the
| panels produce for ~7-8 hours. The 3 hour around noon it's
| about 1/2 the output for the day (for Jan 1).
| mkl wrote:
| The article claims it's much higher output per acre:
|
| > conventional solar technologies, which typically require five
| to 10 acres of land per megawatt of capacity. Erthos claims
| that its mounting scheme requires less than 2.5 acres per
| megawatt.
| s1artibartfast wrote:
| They claim the power per acre is 4x higher than tilted panels.
| Seems like a stretch, but I don't know how bad the density is
| in tilted installations. I guess I have seen some where you can
| drive between rows
| whatshisface wrote:
| The amount of power landing on an acre is fixed, what you can
| achieve by tilting is having less solar panel surface area per
| ground cover area. If solar panels are cheaper than the
| mounting hardware (wow) then there is no reason not to let them
| lie flat on the ground (it's not as if the racks were holding
| them above tree shadows, or anything).
| guerrilla wrote:
| > If solar panels are cheaper than the mounting hardware
| (wow)
|
| I'm surprised this surprises people... Every electronics
| hobbyist knows that electronics are cheap as dirt while any
| kind of box, mount, rail or whatever is BY REALLY FAR the
| most expensive part of a project, even when buying massivly
| mass produced cheap Chinese junk.
| whatshisface wrote:
| The electronics you're talking about are rice grain sized
| little things, while the solar panels are big sheets of
| silicon inside of glass, etc.
| davelondon wrote:
| It's amazing how so few people understand this.
| whatshisface wrote:
| I think people are imagining that solar panels have
| directionality like most photodetectors do.
| rootusrootus wrote:
| > you get a a lot around noon and then very little.
|
| That's a little harsher than reality. You get a very pretty
| bell curve. I have a flat panel on the roof of my RV and I
| track the output over time. I'm not 100% how much of the loss
| in output is because the incidence to the panel is changing, or
| because the light from the sun is going through more
| atmosphere. Probably a little of both, but in any case the
| panel is still plenty useful even when not pointed directly at
| the sun.
| hindsightbias wrote:
| Seems like they would have to do some grading to clear anyway,
| why not grade with some tilt.
| elihu wrote:
| With tilted modules, you'd normally space them out quite a bit
| so the shadows of one aren't falling on the module next to it.
| If they're all flat, that's not a problem so you can space them
| closer. So, it makes sense that they'd get more power per acre
| than the conventional approach -- the panels are individually
| less efficient, but there's a lot more total solar panel area
| per acre.
|
| That might not always be a good tradeoff, but maybe at least
| some of the time it is.
| avip wrote:
| They don't claim to outperform fixed-tile or SAT on that KPI.
| They claim to reduce upfront cost of installation, construction
| time, and general project risk.
| anko wrote:
| aussies are doing a similar thing although they install by
| pulling via tractor and the panels concertina out see
| https://suncable.energy/
|
| they are doing an underwater cable to supply energy to singapore
| Klasiaster wrote:
| Dead ground is not so good for biodiversity, with the standard
| way you have wild grass and flowers beneath.
| elihu wrote:
| Covering the ground with impermeable surfaces isn't great
| either. (Maybe they have drain holes at regular intervals so
| that's not as much of a problem?)
|
| I'm guessing they will probably need a tall fence around the
| outside to keep deer away.
| idiotsecant wrote:
| Seems weird. How do you service it? How do conductors work? How
| do you keep random junk from blowing on top of it? How do you
| clean it? The photo in the story just looks like a giant square
| of PV material. Is that really what this is?
| pavon wrote:
| First, they are banking on the fact that solar doesn't need a
| lot of repair and maintenance in general, and their design
| decreases some of the stresses that racked solar panels
| encounter. I imagine they are also over-sizing the system, and
| adding remote disconnects so they can disable a certain number
| of panels and still meet the contract.
|
| And then when repair is needed, they just walk on it[1].
| Seriously. I'm very curious as to what these pads they mention
| are like - big foam snow shoes, or walkways they rollout along
| a seam?
|
| [1] https://www.erthos.com/reducing-degradation-rates-with-
| earth...
| avip wrote:
| Likely something akin to deminers weight-spreading shoe pads.
| They have to meet panel manufacturer's certified pressure
| spec.
| jsight wrote:
| Oh, that's interesting. And I guess if they do manage to
| break a few panels, they can be replaced cheaply. Its
| probably still cheaper than dealing with racking.
| jl6 wrote:
| Maybe if it reduces installation cost enough they will be able
| to tolerate some inefficiencies.
| [deleted]
| function_seven wrote:
| There's another link with better details on all of that:
|
| https://www.canarymedia.com/articles/solar/erthos-rakes-in-1...
| luhn wrote:
| Re cleaning, they have a cute little robot that you can see on
| this page: https://www.erthos.com/energyservices It's also
| visible in the photo in the article.
| thinkmcfly wrote:
| They should fix the wheel spacing so it rolls on the metal
| frame and doesn't scuff up the edge of the panels
| happyopossum wrote:
| > They should fix the wheel spacing
|
| Sounds like they optimized it for their use case:
|
| "The load of the robot is distributed almost entirely to
| the module frames rather than the glass module"
| nine_k wrote:
| The robot is cute!
|
| I wonder what happens after a major rain though. I suppose
| the panels are weatherproof. But they lie _directly_ on the
| ground, and I did not notice any mention of a drainage
| system. The panels will eventually sag under load from
| rainwater, preventing it from flowing off them.
|
| They mention that their installation can withstand a
| hurricane. I understand how it works for the wind load, but
| every hurricane I witnessed brought a lot of rain.
|
| EDIT: Apparently they embrace flooding, and say that their
| panels and connectors can withstand being submerged in water.
| That's the spirit.
| xnx wrote:
| Reminds me of M-O from Wall-e
| https://pixar.fandom.com/wiki/M-O
| jsight wrote:
| Presumably the plan is for them to be high enough relative
| to the surroundings that the water runs off rather than
| pools.
| robocat wrote:
| I wonder how they manage drainage and surface flooding?
|
| Image of robot on panels: https://static.wixstatic.com/media/
| 3b0818_1667facfc56e475e8f...
|
| The image also seems to show water damage in the corner of
| the closest panel.
|
| At a guess, they target areas without heavy rainfall, and
| fast draining soils. I didn't see any drainage works in the
| video https://vimeo.com/556421759, nor did my google-fu help
| me find anything where they address the issue.
| 88913527 wrote:
| I would have expected it to be like agricultural products --
| rows of corn with spaces between rows, so you could access the
| interior without stepping over the outer panels.
| [deleted]
| Kye wrote:
| It looks like they work in a similar way to wood floor panels.
|
| https://vimeo.com/556421759
| idiotsecant wrote:
| Huh, interesting video. Seems like a cool idea.
| walrus01 wrote:
| It is correct that mounting costs and labor can be a large
| portion of the total BOM.
|
| Even for a large off grid whole home PV system that can operate
| through December/January at high latitudes.
|
| Let's say for an example you wanted to DIY a PV system that would
| be much too large to fit on the roof of a normal sized house.
|
| Go calculate the cost of buying 30000 kW of good quality 72-cell
| PV panels rated at 380W STC each. It'll be something like 80
| pieces at about $130 per piece.
|
| Usually would ship as 20 panels per pallet, so call it four fully
| loaded pallets of 72-cell panels.
|
| At 34 cents/W STC rating, PV panel cost from distributor
| something like $10,400 to $12000 USD.
|
| The foundation work and poles/racking to do a basic ground mount
| will be a huge cost on top of that. Labor is a big part of it. If
| you're hiring people to build it the labor and ground mount gear
| and things like basic foundation work/screw piles/steel tubes set
| into concrete could easily cost you another 10 grand from a local
| contractor.
|
| Something generally along these lines or an industry competitor
| of it:
|
| https://www.ironridge.com/ground-based/
|
| (Not discussing inverters/charge controllers/batteries/disconnect
| boxes and wiring here).
| liketochill wrote:
| I hope the fields never flood and the solar farm is under water
| function_seven wrote:
| > _The glass / glass modules and the connectors we specify are
| all rated for submersion, so flooding is not a catastrophic
| event in case it does occur._
|
| From: https://www.canarymedia.com/articles/solar/erthos-rakes-
| in-1...
| idiotsecant wrote:
| It looks like they're probably targeting places where huge rain
| isn't an issue and it looks like they do some site work to
| raise it up a bit? Theres another photo here :
|
| https://www.canarymedia.com/articles/solar/utility-scale-sol...
| adwww wrote:
| Would it not contribute to flooding as well, unless drainage is
| somehow improved around each panel.
| sieabahlpark wrote:
| sschueller wrote:
| This reminds me too much of solar roadways.
|
| What about heat dissipation? Don't you want airflow under the
| panels?
| dokem wrote:
| laluser wrote:
| > less than 2.5 acres per megawatt
|
| This is actually quite amazing. I wonder what the lifetime is for
| the panels.
| AnimalMuppet wrote:
| That sounds like if I have a decently-sized suburban yard, I
| should be able to throw enough of these out there to run my
| life.
| jsight wrote:
| Usually the expected life is ~30 years. They may last longer. I
| do wonder if pests and moisture will be early failure causes in
| this configuration though. Then again, if it saves enough
| money, maybe that doesn't matter.
|
| TBH, the part that lasts the least amount of time is often the
| inverter.
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