[HN Gopher] Solar on Warehouses
___________________________________________________________________
Solar on Warehouses
Author : ZeroGravitas
Score : 63 points
Date : 2023-04-23 19:52 UTC (1 days ago)
(HTM) web link (environmentamerica.org)
(TXT) w3m dump (environmentamerica.org)
| gumby wrote:
| By the way, this was the thesis of the unfairly* maligned
| Solyndra: their collectors were extremely light and encased in
| tubes. The idea was that they were light and could be anchored
| without through holes to joists (every through hole in a roof is
| a leak opportunity for a leak, especially when it's a retrofit;
| with the weight of panels on a flat industrial roof you often
| have to anchor them to a structural member). Also the tube
| structure permitted airflow so there wasn't a heat build up nor
| risk of a "wing" phenomenon.
|
| * one political party chose to use Solyndra as a cudgel against a
| reasonable industrial program. I was always dubious that their
| thin film approach would pan out, and indeed it didn't which was
| what killed the company. But admired their basic thesis, which I
| still think was sound.
| myself248 wrote:
| For a while, Batteryhookup was selling pallets of Solyndra
| modules for unbelievably cheap. I think it's difficult to use
| them on buildings now because the NEC's new rapid-shutdown
| requirements effectively made decades of solar stuff obsolete
| (welp so much for the environment), and they're not useful for
| making solar carports and stuff. But maybe someone with a lot
| of land...?
|
| Anyway, it's a shame. They were a really neat concept and
| sidestepped a lot of issues that raise the cost of other
| systems.
| Animats wrote:
| Is rooftop solar used mostly to power air conditioning and
| lighting cost-effective for large stores?
| epistasis wrote:
| It's likely far cheaper than buying the electricity from the
| grid, but it will depend on local commercial electricity rates.
| Utilities usually have to set up pretty perverse schemes in
| order for solar to not be an economical choice.
| lucb1e wrote:
| Utilities would have to sell below the raw production cost
| price before that becomes the case, so that's not very likely
| to happen.
| jgelsey wrote:
| The core obstacle is financing - solar traditionally takes a long
| time to pay back from energy savings, so the financials of solar
| on warehouses didn't work out. The IRA made it possible to sell
| the tax credits from solar deployment on warehouse roofs (e.g.
| https://www.reunioninfra.com/) so now solar on warehouse rooftops
| can make financial sense in many more instances.
| Dowwie wrote:
| How are disputes about roof maintenance settled among a roof
| tenant (the energy company), the tenant of the warehouse, and the
| owner of the building? If a roof is leaking but repairing the
| leak will interfere with energy production, how are repairs
| prioritized? This is an easier situation to handle when there is
| no energy tenant nor warehouse tenant but rather an owner-
| occupied who is also the energy provider.
| polygotdomain wrote:
| It all depends how the leases are written and who's responsible
| for the solar panels. Since the panels could potentially be the
| landlord's, warehouse tenant's, or a third party roof tenant's,
| it could be written up in a variety of ways. The Landloard is
| going to be the most concerned about it as A) it could
| potentially effect the base building, and/or B) tenants may
| take issue with a leak. Chances are the repair would be rolled
| up into CAM (Common Area Maintenace) charges, which are
| generally dispersed to the tenant based on an arrangement in
| the lease (typically % of cost based on % of sq ft of the
| property).
|
| The best chance for it to be handled some other way is if the
| warehouse tenant and the solar tenant are one in the same. The
| landlord will still likely be involved, but chances are the
| tenant will do the repair.
| unixhero wrote:
| Well Duh. Isn't this blindingly obvious?
| Syonyk wrote:
| The short answer is "No, but it sounds obvious if you don't
| know much about it." Similar to Solar Roadways - the less you
| know about solar or roads, the better the idea sounds. The half
| mile gouge down a road near me from a trailer coming free and
| riding on the chains until they noticed and pulled over isn't a
| big deal on asphalt (they'll fill it next time they chipseal
| it), but it would be millions of dollars worth of damage to
| solar road tiles. Among many other issues.
|
| It's the sort of thing that sounds obvious if you don't know
| much about the field, and the more you learn, the more things
| you realize make it a royal pain in the rear to deal with
| unless the structure was designed with solar in mind - and even
| then, it's a pain compared to a ground mount array somewhere
| close.
|
| For a big membrane roof, you don't want a ton of penetrations -
| which means ballasted mounts. Except they weigh a lot, and the
| roof usually isn't built to support them on top of the required
| weight for rain/snow/etc. So you need to screw the stuff down
| to the roof, but now you have tons of penetrations in a
| membrane roof, and if anyone tells you they can do thousands of
| those without a single leak, they're full of crap.
|
| As I talked about in another comment, you can't just run high
| voltage DC strings on a roof - you need per panel electronics,
| so the normal solution is microinverters, but now you're
| pushing 240V around instead of the 1500V you can run on ground
| mounted strings, so wiring cost is higher, and Enphase sure
| makes their money off their handout in the NEC 2017.
| Reliability of microinverters remains an open question as well.
| They're not exactly in a good spot for electronics.
|
| You've got open area, you've got a high current
| interconnection, but the rest of it is just a set of thorny
| problems that makes it quite a bit more expensive than ground
| mount.
| unixhero wrote:
| Tha k you for an illumination comment. I learnt some of the
| intricacies of flat roof mounts. Cheers.
| powera wrote:
| This misses the point. The limiting factor for solar isn't real-
| estate. It is inverter production, battery capacity,
| interconnect, ... basically all of the parts of turning solar
| energy into grid electricity other than the land for solar
| panels.
| jeffbee wrote:
| When you see something like [1] in the center of a city of 10
| million people, that's a lot of potential for energy generation.
| And the great thing about putting a ton of panels in the middle
| of the city is it tends to avoid all the transmission issues we
| have with siting PV facilities way out in the desert.
|
| 1:
| https://www.google.com/maps/@34.0297809,-117.9823821,3248m/d...
| hnburnsy wrote:
| Both Amazon and Walmart have pulled back on solar due to fires
| and electrical issues...
|
| https://www.cnbc.com/2022/09/01/amazon-took-solar-rooftops-o...
|
| https://www.cnbc.com/2019/11/05/tesla-and-walmart-settle-ove...
|
| Might have been a Tesla issue in both cases.
| epistasis wrote:
| Everybody I know that used Tesla for solar regrets it. Cheap
| stuff, but you end up paying for it in the end.
| bufferoverflow wrote:
| When we installed solar, Tesla's was the most expensive out
| of all the proposals. Their solar roof looks very very cool,
| but it's definitely not "cheap stuff".
| liketochill wrote:
| In utility scale solar tesla product is vapor ware or under
| development to the point a 50 MW project is having major
| difficulties
| Syonyk wrote:
| Tesla has two solar products. Don't confuse them.
|
| The first is the "solar roof" sort of thing that... we'll
| see how maintainable it is, but you get to write a properly
| large check for it, and most of the people I know with it
| have a couple Powerwalls, and are quite adverse to sharing
| any sort of actual pricing on it, muttering about "Well,
| wife acceptance factor" and "But it'll be worth it in power
| outages..." and such. In other words, almost certainly
| north of $5/W, and they likely didn't get an itemized
| invoice of materials/labor/etc.
|
| Tesla also, in some markets, has a "standard solar panel"
| offering that typically comes in around $2.50/W, give or
| take, and... well, you get what you pay for, typically. It
| ranges from "decent and a good deal" to "a hot mess," and
| you've no idea what you're going to get ahead of time.
|
| ... and then there are people like me who have sub-$1.50/W
| installs (DIY). Mine came in around there, but after
| figuring out how to optimize it better, a neighbor's build
| came in around $1/W for a 21kW system.
|
| //EDIT: And, yes, it takes a lot of learning to do. Cross
| that with the tens of thousands of dollars saved, I think
| it's well worth the hassle.
| epistasis wrote:
| Never heard of anything like that, but most of my
| experience is from 2+ years ago. Is your install recent?
| Are you sure they were equivalent proposals? If you add
| storage, that's no longer just solar, and their storage
| offerings are far more expensive than others.
|
| I couldn't find a local solar installer that wanted to use
| the type of cheap inverters that Tesla wanted to use. My
| neighbor has to have Tesla come out about once a year to
| fix issues.
| travisporter wrote:
| https://www.pv-magazine.com/2021/06/11/amazon-warehouse-fire...
|
| I think it's linked to installation. Some sources say they
| didn't remove them after the fires
| Syonyk wrote:
| I've no idea why you're being downvoted, because it _is_ a very
| real issue. You don 't have to burn down many warehouses with
| solar before insurance companies start to have a lot of hard
| questions and rate increases. In tens of thousands of
| connections, it doesn't take a high failure rate on components
| before you've got something high resistance.
| vasco wrote:
| And if you have to evacuate a huge warehouse even once a year
| due to these fires, it immediately is not worth it for the
| operator.
| tomcam wrote:
| Could you elaborate? I feel like I'm missing something
| significant. I am imagining people file out, then file back
| in a few hours later, which seems harmless-ish.
| scohesc wrote:
| I would assume downtime in terms of "we're paying all
| these warehouse workers to stand outside - now we have to
| send them home and the warehouse is unusable, we don't
| know if the product inside is salvageable due to
| potential water damage, etc. etc."
|
| Probably a lot easier on the business risk side of things
| to not have solar on the roof because then the risk for a
| fire is massively reduced in the first place.
| [deleted]
| photochemsyn wrote:
| Structural design issues are the problem as other comments note.
| If you haven't designed the roof from the beginning to have a
| fairly weighty additional structure attached on top, then all
| kinds of other problems can arise, from leaks to wind-related
| loads and so on.
|
| Over the long term, it becomes something building codes need to
| implement, similar to electrical wiring and plumbing standards:
|
| https://www.nrel.gov/state-local-tribal/blog/posts/solar-rea...
| toomuchtodo wrote:
| NJ has code that requires structural loading on new warehouses
| to be able to support solar on 40% of the roof. It's just a
| matter of getting this into code as soon as possible, so new
| buildings are solar ready as old warehouse space is eventually
| retired at EOL.
|
| https://www.jdsupra.com/legalnews/new-jersey-solar-ready-req...
| cagenut wrote:
| wow thanks for sharing that link, what a fantastic policy.
| SoftTalker wrote:
| Yes, and in areas that get snow the roof would need to be
| strong enough to support the max snow weight plus the weight of
| the solar gear. I don't know how much safety factor most
| buildings have, but many might require additional
| reinforcement.
|
| I know of a city building here where they wanted to install
| solar and as they got into it realized they would need to hire
| a steel company to come in and reinforce all the steel roof
| trusses. That was custom work with welders up on scaffolds and
| a lot of other work to remove lighting and other fixtures to
| give them access (and then reinstall it all afterwards). They
| went ahead with it but with the extra expense it will never be
| paid back in electrical savings.
| bjelkeman-again wrote:
| This would seem to be more common from a business perspective,
| but apparently it isn't. This warehouse park, Morgongava, near
| Uppsala in Sweden has at least 2.5 MW installed and installing
| more. This one of their buildings.
|
| https://renewablesnow.com/news/swedish-online-pharmacy-apote...
| rhdunn wrote:
| It's interesting that they are selling the excess to the local
| supplier as they will be able to offset the cost faster, and
| start making a profit from it sooner. That is, the point at
| which the amount of money saved from not paying for the
| electricity and the amount gained from selling the excess
| balances the cost for the installation.
| PaulKeeble wrote:
| This happens in residential solar a lot. During the
| Spring/Summer/Autumn you will produce 1.5x - 2x what you
| consume on any given day but the peak of the power all comes
| at 9-10am to 2-3pm. You need large amounts of battery to move
| that power to cover the house for the other 2/3 of the day
| and that adds a lot of cost and is often similar price to the
| solar array.
|
| One of the best ways to deal with the problem is selling it
| back to the grid but how that is done vastly changes the
| payback period. Some states do it as a unit exchange so you
| sell 1KWh to them then you get that back later when you want
| it for no cost. Whereas many do a sale price with a price
| half or worse. Which price you can get for that power and
| whether its following wholesale (which tends to be peak early
| evening and be more during the day than night) can
| drastically change the pay off period.
| ajsnigrutin wrote:
| So, power when you're not at home, the house is empty, it's
| warm, and your electric car is with you at work, and no
| power at night, when you need to cook, heat and charge your
| car.
| morsch wrote:
| Your house can act as a thermal battery and draw power to
| heat or cool it while there is a surplus. You can also
| have a hot water reservoir as another large thermal
| battery for showering etc.
| Syonyk wrote:
| Yup.
|
| This is one of the reasons I've argued in favor of "slow,
| at work charging" as the default for EVs. If you put in a
| bunch of 240V/16A chargers (3.8kW), as people show up in
| the 8-9 timeframe, they start charging, and the bulk of
| the charging happens in the ~10AM-2PM window that's after
| the morning peak, as solar is ramping up, and before the
| afternoon cooling/evening peak. You can even restrict the
| chargers a bit more in the morning if needed until off
| peak, though I'm not sure this is worth much over just
| using dumb chargers that are cheap to install. An average
| 35 miles a day driving (in the US) requires ~10kWh, so
| you've got a few hours of charging that can swallow an
| awful lot of power during the time nothing else is using
| much of it.
|
| It's far better than having to deal with evening and
| overnight charging.
| ajsnigrutin wrote:
| But for that you need every parking space in every office
| building equipped by a charger, and somehow have the grid
| strong enough to power all that from solar cells which
| need to be installed somewhere further away, since an
| average office building does not have enough roof space
| to charge all those cars. The hours you mentioned are
| usually spent at work and the cars are parked there (and
| not at home).
| Syonyk wrote:
| Who said every parking space? I didn't. Even at the
| coastal FAANG offices, EVs are still the minority. And
| not everyone will be charging every day. It's still fine
| to have a lot of non-charging spots - some people have
| short commutes and can be perfectly fine charging for
| 8-9h once a week (at 3.8kW, that's around 100 miles in 8h
| of charging). My experience from the early to mid teens
| is that the Leafs fought for charging, and the longer
| range BEVs charged if they could, and otherwise didn't
| get in the (damned near literal) fistfights over
| charging, but if someone showed up early, they'd plug in
| for the day.
|
| If you look at grid demand curves, that "late morning,
| early afternoon" time spot is the mid-day low for _most_
| grids. So there 's excess capacity anyway, and if you
| look at the "duck curve" sort of graphs, there's a ton of
| solar on the grid then anyway. This is only increasing
| with time. So we may as well make decent use of it.
|
| You could also have some lower power, 1440W charger slots
| (15A @ 120V) for those who don't need much power - it'll
| still make up an average day's driving in 8h of charging,
| but since it's literally the same wiring cost and such to
| run 120V as 240V, I'm not sure you gain much with it, and
| it's now perfectly valid for chargers to coordinate
| regarding total circuit demand anyway.
| ajsnigrutin wrote:
| > Who said every parking space?
|
| I did... if you want to stop selling gas powered cars by
| 2035 (or whatever the current cutoff date is), you need
| pretty much every parking space fitted with a charger in
| ~2040, since electric should overtake gas powered by
| then.
|
| High power, low power,... it doesn't matter if you don't
| have physical chargers installed pretty much everywhere,
| and enough solar installed to cover the power usage. This
| is not "distant future", this is less than 20 years away.
| Suburbia is simple, because most people have an outlet in
| their garage, but they can only charge at night (no
| solar), apartment buildings have basically the same
| issues as office car parks, but with energy needed at
| night, and if you really want to utilize solar, you need
| chargers at office car parks too.
| [deleted]
| lucb1e wrote:
| > Who said every parking space? I didn't. Even at the
| coastal FAANG offices, EVs are still the minority.
|
| Might just be me, but I read any comment talking about an
| ideal future scenario for charging vehicles (if not
| otherwise qualified) as being for the ideal world where
| the 99% switched to electric vehicles.
|
| If you're talking about planning for the situation that
| we have _today_... that doesn 't seem too useful and
| would be outdated in two-odd years.
| matthewdgreen wrote:
| Compared to all the problems humanity faces (such as
| _not_ addressing the low-carbon energy transition) it's
| hard to be intimidated by a situation where EVs become
| wildly popular and we have to spend a modest fraction of
| their cost on wiring charging infrastructure and grid
| upgrades (a cost we can amortize over decades.)
| ajsnigrutin wrote:
| It's not an "ideal future".... considering how many
| countries promised that they'll ban gasoline powered cars
| by 2035 it's something we should already start building
| (both the solar side and the chargers).
| jpgvm wrote:
| Has anyone done more detailed numbers on costing of roof mounted
| installation vs just putting utility scale solar on the ground?
|
| I would have thought if the economics were super favourable this
| would already be happening by now.
|
| To me it -seems- like a great idea but while I'm pretty versed in
| solar for home scale (diy off-grid setups etc) I have no idea how
| the numbers bear out for this install size, grid connection, etc.
| notatoad wrote:
| we massively under-value land in most cases, which is the
| reason that activists push for solutions like this.
|
| utility scale solar on the ground is economically better, if
| you're looking at "the numbers". but utility scale solar
| probably means repurposing farmland, because that's the
| cheapest land that has enough infrastructure built up around it
| to make a utility install easy. and repurposing farmland to
| build solar isn't a clear win in terms of overall societal
| benefit.
| epistasis wrote:
| Converting farm land into solar, or even fallow land, seems
| like a massive societal benefit. Most farmland is
| fantastically unproductive, used for excess corn, soy, or
| sugar that we struggle to find uses for.
|
| Taking even a fraction of the land used for ethanol and using
| it for solar would give us enough energy to power the US. And
| the ethanol business is a complete make work program.
| Syonyk wrote:
| > _... but utility scale solar probably means repurposing
| farmland..._
|
| Great. Let's start by repurposing the land that grows the
| corn we turn into ethanol at somewhere around or below unity
| EROEI, as a political handout to the midwestern states.
| "Burning a megajoule of diesel, to grow enough corn to make
| something slightly less than a megajoule of gasoline," is
| _not_ a winning solution to any problem but "How to best
| hand money to states that happen to have early Presidential
| primaries." It's not a bad gig for Iowa (I lived there for a
| decade), but neither is it a particularly good use of energy,
| fossil fuels, or money. Let's put solar up there, and work
| out.
|
| Once we've gotten rid of the ethanol debacle, we can see
| where things are and discuss from that point, but there is a
| _lot_ of farmland right now that doesn 't grow human or
| animal food, it grows corn that we process rather
| inefficiently into ethanol.
| notatoad wrote:
| i completely agree, but as long as this is all driven by
| economics the existence of those corn subsidies is going to
| mean the farmland that gets repurposed won't be the
| farmland that gets the most government subsidies, it'll be
| the farmland that grows the cheap food that people need to
| eat.
|
| i know ethanol farming is a waste, but it's a lot easier to
| convert a corn field back into a useful farm field before
| you've built a solar farm on top of it, rather than
| afterwards
| shkkmo wrote:
| > it's a lot easier to convert a corn field back into a
| useful farm field before you've built a solar farm on top
| of it, rather than afterwards
|
| Or you can do agrovoltaics and have both. There's some
| evidence that low density agrovoltaic setups increase
| corn yields.
| algo_trader wrote:
| > Has anyone done more detailed numbers..
|
| This is usually under "C&I" (commercial and industrial), as
| opposed to rooftop or utility scale.
|
| Try Lazard LCoE report, NREL Solar reports, IRENA renewables,
| or use google.
| Syonyk wrote:
| > _Has anyone done more detailed numbers on costing of roof
| mounted installation vs just putting utility scale solar on the
| ground?_
|
| You're far cheaper on the ground, for a variety of reasons (at
| least in most areas). A good ground mount install should be
| able to come in around $1/W, and you'll have a hard time
| getting roof mount below closer to $1.50 or $2/W installed, and
| if you get $2/W, you're getting a great deal.
|
| If you're doing the work yourself, ground mount for around $1/W
| is doable (including the frames), but roof mount I've not been
| able to get below about $1.25/W, and that's hard - $1.50/W is
| more typical.
|
| The main difference is that the roof mount system requires
| rapid shutdown on (in NEC 2017 and later) every panel, and
| you're limited to 600V (though with rapid shutdown
| requirements, this is less relevant). For a ground mount system
| that's isolated away from random people (fenced area), you can
| run up to 1500VDC to the inverters, and this rather reduces
| your costs in wiring. You also don't need rapid shutdown, so
| you can just run strings of panels (20 or 25x 72 cell panels in
| series, depending on the environment).
|
| Also, if those strings have an arc fault somewhere, you're not
| going to burn up much that matters for a big ground mount
| install. You'll cook a couple panels, and that's about it. A
| fire under the panels on a warehouse is a much bigger deal.
|
| The main problem you run into with warehouses, though, is that
| there's just no good option for mounting. For a flat roof,
| they're generally built to exactly the loading requirements for
| the area. You don't have the spare PSF capacity for a ballasted
| mount, which means that assuming you've got the weight rating
| for the panels, you're looking at a _lot_ of roof penetrations
| on a flat membrane roof to hold stuff down - and the odds of
| some of those leaking is basically 100%.
|
| Plus it's a royal pain to work on roof mount systems.
| s0rce wrote:
| Do you know how the numbers compare for green field projects
| on the ground? They keep building new projects in otherwise
| wild/wilderness areas instead of on rooftops.
| jpgvm wrote:
| Thanks for the great writeup! The root loading makes perfect
| sense when you think about it and in that context makes the
| equation much more expensive unless the warehouse could
| feasibly use all the power generated (which seems unlikely).
| hijinks wrote:
| ya till solar hits a tipping point like it is in California right
| now. Then the utilities want to set a flat rate based on wages to
| stay connected to the grid.
|
| This will 100% work but we also need battery tech to hit like
| 250-300 a kwh for storage is my magic number to get a 40-50kwh
| backup and detach from the grid.
| krasin wrote:
| > we also need battery tech to hit like 250-300 a kwh for
| storage is my magic number to get a 40-50kwh backup and detach
| from the grid.
|
| Here you go, a 30kWh 48V battery for $9k ($300/kWh):
| https://signaturesolar.com/eg4-lifepower4-lithium-batteries-...
| hijinks wrote:
| wow thanks.. looks perfect
| epistasis wrote:
| The storage market has been revolutionized in the past few
| years thanks to LFP chemistries, and it's only going to get
| better soon. There are massive new US production facilities
| coming online, and Bloomberg is estimating that US cell
| costs will be $83/kWh, just a few dollars more than Chinese
| costs. Add in the IRA tax credits, and the cost will be
| less than $50/kWh. Packs will be more expensive than cells,
| of course, but the future looks very rosy. Could see that
| pack at half its current price, even in quantities as small
| as 50kWh.
|
| I always chuckle when I encounter the sweet summer children
| that think that battery tech is stagnant...
|
| (Subscription required) https://www.bnef.com/shorts/16235?e
| =Insight%20Alert:sailthru
| jandrese wrote:
| It's an extremely common argument from renewable
| opponents that storage is just too expensive and will
| never be economical. If you manage to get them to write a
| number down it's always something like $500-$1000/kWh
| because that's what some old fossil fuel study from the
| 90s used.
| hijinks wrote:
| I guess the idea is just to wait a few years then.
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(page generated 2023-04-24 23:02 UTC)