[HN Gopher] Roll-to-roll fabricated perovskite solar cells under...
___________________________________________________________________
Roll-to-roll fabricated perovskite solar cells under ambient room
conditions
Author : gnabgib
Score : 129 points
Date : 2024-04-11 05:41 UTC (17 hours ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| tgsovlerkhgsel wrote:
| 70 USD for 100 W seems pretty bad? Especially given the low
| efficiency.
| f_devd wrote:
| I would expect the price to decrease over time given perovskite
| solar cells are currently not yet mass produced and still
| actively being researched.
| pfdietz wrote:
| Or, the degradation problems keep them from ever taking off.
| If they do, they may only do so as part of tandem cells with
| a silicon PV bottom layer.
| aredox wrote:
| A quick look around gives me a current figure of ~1 USD/W in
| Australia (dunno if that evolved a lot in a short time with the
| current inflation and currency rates).
|
| Money quote:
|
| "The cost for [production] Seq[ence]. B is likely to be lower
| than 1 USD W-1, and Seq. C could be lower than 0.5 USD W-1.
| These represent a significant reduction to the cost estimate
| from previous works of around 1.5 USD W-147. This results from
| a similar or lower cost in $ m-2, and a higher recorded
| efficiency. However, the technology is still not able to
| compete with mass-produced silicon solar cells, for which
| module spot prices have been lower than 0.30 USD W-148. Despite
| this, opportunities may exist in niche markets that value the
| lightweight and flexible nature of these modules, as discussed
| in our previous work47. The next step for the technology would
| be exploring high-value PV markets at the predicted
| manufacturing costs while addressing the remaining high-cost
| components to sustainably advance the technology towards
| commercialisation. Supplementary Fig. 12, with about 5 USD m-2
| module cost (excluding encapsulation), shows the potential for
| the further cost reduction by eliminating the remaining high-
| cost components."
| hackerlight wrote:
| The cost model is based on high labor cost assumptions of
| $25-36 USD/hr. See page 14 below. I wonder how much lower
| China's industrial capacity could reduce the costs.
|
| https://static-content.springer.com/esm/art%3A10.1038%2Fs414...
| londons_explore wrote:
| The market need for cheaper solar cells seems to have evaporated,
| since the vast majority of the cost of solar projects these days
| is always in labour/land/wiring/inverters/grid
| connection/maintenance contracts.
|
| That means saving a bit of money on the panels in return for
| lower efficiency is never a good deal.
| hackerlight wrote:
| Some are trying to combine perovskite with silicon solar cells
| because they specialize at capturing different wavelengths. So-
| called tandem solar cells.
| selimthegrim wrote:
| I wonder what happened to singlet fission cells and other
| things trying to get around the SQ limit
| pfdietz wrote:
| Still being worked on.
|
| https://interestingengineering.com/energy/paderborns-new-
| sol...
| selimthegrim wrote:
| Thanks for the link - I used to be peripherally involved
| in this field and last I heard MIT (Baldo et al.) had
| resorted to some hafnium oxynitride layer, which is
| really not gonna drive costs down at all.
| ElevenLathe wrote:
| If the materials are cheap enough, we might be able to build
| them into other stuff that was going to use labor anyway
| (shingles, asphalt, siding, etc). No idea what the economics of
| this look like though, and electricians (a pretty expensive
| form of labor) will need to be involved no matter what, but at
| least theoretically cheaper cells can also deal with labor
| costs.
| hackerlight wrote:
| Like solar fences: https://next2sun.com/en/solar-fence/
| KeplerBoy wrote:
| Solar panels are already cheaper than wood, which is
| amazing.
| sandworm101 wrote:
| Where are PV panels cheaper than wood? A 4x8 sheet of
| plywood runs about 40$ in north America, and roughly
| double that in Europe. I don't see PV panels anywhere
| near that price.
| abathur wrote:
| I can't recall ever seeing a plywood fence in North
| America.
| jandrese wrote:
| You do see them from time to time in especially rough
| rural areas. I can remember one that was apparently
| painted from the "oops" paint section of the local
| hardware store surrounding a strip club next to a
| junkyard.
| abathur wrote:
| Sure. I don't recall seeing one, but the near-
| inevitability of this is why I didn't assert they don't
| exist.
|
| Rarity speaks to how poorly suited the material is for
| building durable fences and the ~irrelevance of the cost
| of plywood in this subthread.
| KeplerBoy wrote:
| You don't want a plywood fence though. PV panels are
| cheaper than the decorative wood fences are made of. Wood
| fences are easily 100EUR/m around here.
| Osiris wrote:
| It's not cheaper than wood. It's cheaper than certain
| specific kinds of wood used in specific applications.
|
| A 2x4 stud is like $3, for example. Decorative cedar is
| quite a bit more expensive.
| Teever wrote:
| I don't think that you actually thought that the person
| you're replying to said that solar panels are now cheaper
| than all wood always.
| specialist wrote:
| Ya, that's my take too. Continuing R&D on alternatives like
| perovskite might open up new use cases. Like using
| transparent solar cells as windows. It's worth investigating.
|
| Bonus, it keeps scientists employed, maintaining our
| capacity.
| sandworm101 wrote:
| >> other stuff that was going to use labor anyway (shingles,
| asphalt, siding, etc)
|
| No. None of that ever works. Everyone has the "good idea" of
| cramming PV into some other product thinking that doing so
| will somehow reduce labor. It never does. Solar shingles are
| typical. They sound great but in reality require hundreds or
| thousands of electrical connections all spread over the
| moving flexible surface that is a wooden roof. You will be
| chasing electrical gremlins the moment the temperature
| shifts. And fixing any of those gremlins will involve
| penetrating the waterproofing, the core function of any roof.
| It is far easier to build and maintain a normal roof and then
| mount dedicated panels atop. The same too with siding. Want
| solar walls? Build normal walls and hang solar panels on
| them.
|
| It is like building a computer into a desk. It seems like a
| great idea that will save space and keep your office tidy.
| There are lots of youtube videos about such builds. In
| reality, it is expensive on day one and extremely
| inconvenient to maintain in the long run. Nobody ever does it
| twice.
| mlyle wrote:
| Part of why it doesn't work, though, is that PV is too
| expensive.
|
| If it's cheap enough, you can tolerate failures and poor
| illumination of the panels for things like fence panels or
| whatever.
|
| I do agree you need big panels to not have excessive labor
| from connections.
| sandworm101 wrote:
| >> If it's cheap enough, you can tolerate failures
|
| But you just can't. When you are using lots of tiny
| things all connected through each other then you have
| less tolerance for faults, not more. One bad connector
| can mean that an entire run of shingles is dark. So even
| a 1% fault rate, if you have a few hundred connections in
| each run of shingles, means that basically nothing is
| connected. Or think of a long fence. One broken bit can
| mean the entire fence after that break is no longer
| connected. You're just setting yourself up for a long day
| of checking connectivity only to have the fence shift
| again.
| mlyle wrote:
| Most of what you say was anticipated by the comment you
| replied to:
|
| > > I do agree you need big panels to not have excessive
| labor from connections.
|
| > You're just setting yourself up for a long day of
| checking connectivity only to have the fence shift again.
|
| If only we had ways to make long runs of wiring
| relatively reliable.
|
| My point is: there's second order effects: expensive
| panels need to have as high of a capacity factor as
| possible; high capacity factor constrains installations
| and increases other costs. If you cut 2/3rds of the cost
| of the panel away, other costs decrease, too, and more
| types of installation become reasonable.
| WillAdams wrote:
| PEV in metal roofing seems more workable.
| londons_explore wrote:
| I think future designs of panels might be designed in such a
| way an electrician isn't required. All foolproof plug'n'play
| connectors and designed in such a way you cannot plug them in
| in an unsafe way.
|
| You don't call an electrician every time you plug in a
| hairdryer, and a hairdryer is typically higher voltages and
| currents than a single panel.
| jandrese wrote:
| Higher voltage than a single panel, but a string of panels
| easily hits hundreds of volts. Even worse they can be hard
| to make safe, since as long as the sun is shining they are
| generating energy and roof installers don't like working at
| night.
|
| You can avoid this by using microinverters, but they're a
| pretty substantial premium on each panel and an added point
| of failure.
|
| There is lot of tech around solar panels that is being
| effectively obsoleted by the plummeting costs of the panels
| themselves. Why bother trying to squeeze out the last few
| percentage from each panel when it's so much cheaper to
| just install a couple more panels to make up the
| difference? This is the big difference between countries
| like the US where solar installs are still expensive at
| $3-$6/watt and countries like Australia where home solar
| installs are under $1/watt.
| cogman10 wrote:
| It's even worse, perovskite degrades faster than silicon cells
| so you are getting lower efficiency short life cells. Tons of
| money is being invested in trying to fix the lifespan problem.
| c2h5oh wrote:
| Ground/roof solar is still >60% panels around here
| mensetmanusman wrote:
| Labor costs are less when the weight is 10x less.
| tlb wrote:
| A little, but the design of the support structure is
| dominated by wind loads. Depending on where you are, it can
| need to survive wind gusts of 90 - 160 mph. At the low end,
| 90 mph corresponds to 1000 N / m^2, which is more than the
| weight of any kind of solar panel.
| Workaccount2 wrote:
| I've been waiting for consumer level panels to get cheaper
| forever. You'd think by now that you could get a 200W panel for
| $50. But they have been the same $200 for what seems like a
| decade now (I suppose they didn't go up with inflation, but
| still)
| jakewins wrote:
| You can pull up at MO Wind and Solar off of MO 60 and grab
| 600W panels for $195/ea today:
| https://windandsolar.com/risen-595-watt-mono-solar-panel-
| bif...
|
| That's ballpark where you say, about $65/200W.
|
| They also have remanufactured panels, like the 410W trina
| ones, even cheaper. Good outfit, nice and helpful, bought
| several lots of panels off of them.
| ravedave5 wrote:
| It seems like the size & cost of the panel has stayed the
| same and the power output has gone up.
| whitehexagon wrote:
| I just put another 5x550W panels up 2 months ago, and they
| are now 101eur per panel including tax! 30e less than I just
| paid. wish I had space for more!
| daemonologist wrote:
| It's frustrating. Panels around $0.25/W exist, but it's
| really difficult to get your hands on them in small
| quantities as an individual. You can either string together a
| bunch of tiny eBay specials or drive halfway across the
| country to find a distributor of the panel you want who's
| willing to sell to consumers.
| RisingFusion wrote:
| In Germany, 405 Watt panels new can be had for 65 euros. The
| law allows up to 800W to be connected to homes with
| relatively little bureaucracy, as a balcony solar power plant
| which renters can install without modifying the building.
| This seems to have pushed the price down, so there are many
| 800W kits including panels, an inverter and cables available
| for under 400 euros.
| vinay_ys wrote:
| Cost of labor might be significant in some countries, but in a
| lot of countries, cost of materials is still the significant
| cost barrier to installation of solar. If the cost of materials
| were to come down significantly, even if it is at the expense
| of some efficiency, and also make the installation much more
| flexible, then definitely more installation will happen.
| Capital invested will be recovered in a shorter duration making
| the investment a lot less risky. This makes lending programs
| much more accessible, making the whole thing a more self-
| reinforcing cycle.
| cmrdporcupine wrote:
| It feels like the problem here is less about the solar industry
| and more about the construction and skilled trades generally.
| _Everything_ involving an electrician / electrical contractor
| has gone way up in the last 10-15 years, along with other
| things. So whatever savings are being saved on materials are
| just being eaten up by rising labour costs.
|
| That and government incentive programs for home energy
| efficiency seems to have just inflated prices and stimulated
| demand to make the installation costs worse. Quotes I've gotten
| on heat pumps for example have been ridiculous, and solar much
| the same.
|
| Hate to say it, but a recession might be what "fixes" this. Not
| that I want to deprive trades people of a good livelihood, but
| it feels like the end consumer is getting screwed right now.
| bilsbie wrote:
| True but the cost of labor goes down if they get cheap enough.
|
| For example: buy panels so cheap you just leave them on the
| ground. If they get damaged who cares. Some people are already
| using them as material for fences. Not a great angle, they're
| cheap who cares.
| akamaka wrote:
| Perovskite solar cells are the best candidate for solving the
| problem that you pointed out. The best perovskite/silicon
| tandem cells in the laboratory have 33% efficiency, and the
| theoretical limit for this type of cell is 43%.
| MobiusHorizons wrote:
| Do you know if there is any (even theoretical) work to solve
| the lifetime issue? Perovskites degrade in sunlight (order of
| months) making it seem unlikely they would ever be useful
| outside the lab.
| photonbeam wrote:
| The are plenty of places with really low labor costs that would
| love cheaper panels
| jjk166 wrote:
| > That means saving a bit of money on the panels in return for
| lower efficiency is never a good deal.
|
| This does not at all logically follow from your proceeding
| statement. Cheaper solar panels mean they can be used in
| different ways with different labour/land/wiring/inverters/grid
| connection/maintenance requirements.
| chrisbrandow wrote:
| if the substrate really can remain even a little bit flexible
| however, this opens up entirely new deployment opportunities.
| yareal wrote:
| As an outsider, what's the appeal of PeSC? The paper says they
| are less efficient and harder to manufacture, but also that they
| are the "next generation".
|
| I would have thought the next generation would be more efficient
| or easier to manufacture or both.
| SquareWheel wrote:
| As I understand it, silicon cells have largely been optimized
| to near their peak potential. There's not much room left for
| improvements at this point.
|
| Organic and perovskite cells have a higher potential
| efficiency. Just like was the case with silicon, it will take
| years of development and incremental improvements to see higher
| efficiencies in these technologies. Silicon cells were also not
| very good at the start of their development.
|
| In that sense perovskite has the potential to be the next
| generation of solar cell. New developments, such as the one
| demonstrated in the linked paper, are just a step towards that
| ultimate goal of more efficient solar.
|
| I'm not an expert in this field, so please feel free to correct
| any mistakes I've made.
| thimkerbell wrote:
| Which ones don't have heavy metals?
| pjc50 wrote:
| "Harder to manufacture" is relative. The hope is that they
| would be easier, because they're not monocrystalline and don't
| require the high energy
| https://en.wikipedia.org/wiki/Czochralski_method to produce a
| semiconductor substrate. The paper (and the general "pitch" of
| perovskites) plans to use roll-to-roll printing on flexible
| substrates.
| mchannon wrote:
| a-Si has been at or beyond this level of efficiency since the
| 90's and also does not require a Cz or FZ process.
|
| It's encouraging to see progress but where perovskite thin
| films show potential is in an integrated mechanical stack
| application with silicon, where they can supplement each
| other's barely-double-digit efficiencies focusing on
| different parts of the spectrum to combine to reach something
| on par with traditional crystalline silicon, but thinner and
| with lower production costs.
|
| Seeing thin film beat crystalline silicon is like seeing
| nuclear fusion become cost-effective. It's perpetually 10
| years away, and has been since the 70's.
| riskable wrote:
| The benefit of PeSC is that it _can_ get into efficiencies
| higher than 20% (higher than traditional industrial cells which
| typically top out around 18-19%) but the problem with them to
| date has been the cost of manufacturing. This article is all
| about solving the "cost of manufacturing" problem.
|
| If we can get the cost of manufacturing PeSC cells down to the
| same levels of traditional crystalline silicon PV cells then
| the old style will become obsolete. It's a simple evolution of
| photovoltaic technology with PeSC cells being the next
| generation. Not so different from any tech where it's expensive
| when first introduced but as mass adoption and manufacturing
| improvements take place the cost comes down.
| myself248 wrote:
| Ovonics was doing roll-to-roll solar cells in the 1980s, were
| they not? This is exciting if the technology scales better or
| something, but I can't help feeling that we've stagnated a bit.
| durkie wrote:
| What material though? Nanosolar was also doing CIGS roll-to-
| roll cells, and that didn't work out too well for them.
| chrisbrandow wrote:
| costs of solar panels of all sorts have dropped 100 fold in
| that time. I'm not sure I'd call that stagnation.
| pfdietz wrote:
| PV cells on thin flexible substrates are interesting for space
| applications, where they could have very high power/mass.
| denton-scratch wrote:
| What is "roll-to-roll", in this context?
| pjc50 wrote:
| https://www.ronaldindia.com/all-you-need-to-know-roll-to-rol...
| bionhoward wrote:
| It means, to print long sheets on rollers like a newspaper
| might.
| dr_dshiv wrote:
| Here is the graph of exponential installed solar capacity [1].
| Like Moore's law, continuous technological innovation and
| investment will be required to keep the pace. We just hit 1
| terawatt-- and doubling time seems to be about every 3 years.
| So... 1,2,4,8,16,32,64,128,512,1028, 2056 terawatts in 30 years?
|
| With 20% capacity, that's equivalent to >300,000 Million Tons of
| Oil (MToE) per year. Current global energy consumption is 14,000
| MToE [2].
|
| [1] https://ourworldindata.org/grapher/installed-solar-pv-
| capaci...
|
| [2]
| https://en.wikipedia.org/wiki/World_energy_supply_and_consum...
| sp332 wrote:
| That chart ends at 2022, but 2023 was an even bigger year than
| you would expect from that curve, with over 500GW of new solar
| installed.
| https://www.iea.org/reports/renewables-2023/executive-summar...
| jandrese wrote:
| Ahh, the classic case of seeing the bottom half of an S curve
| and projecting it out to infinite exponential growth.
|
| The number of times things have experienced infinite
| exponential growth in all of history starting from the Big
| Bang: 0.
| ncr100 wrote:
| /jk just wait long enough and that zero will go to Infinity
| axus wrote:
| Isn't the universe expanding exponentially since the Big
| Bang?
| cma wrote:
| The expansion rate slowed down dramatically after the big
| bang and then sped up again, from Wikipedia:
|
| > Cosmic expansion subsequently decelerated to much slower
| rates, until at around 9.8 billion years after the Big Bang
| (4 billion years ago) it began to gradually expand more
| quickly, and is still doing so.
| mikepurvis wrote:
| Sure, but until we see the inflection point we can't know how
| much longer the bottom half of the S curve lasts-- it might
| be 2, 5, 10 years, or it might have already passed; either
| way we'll only know in retrospect.
|
| Those different options make a _big_ difference on how much
| PV is part of the long term global energy picture.
| spywaregorilla wrote:
| Ah the classic case of rounding a two digit number to
| infinity to make a strawman point?
| feoren wrote:
| Nobody said "infinite".
|
| The upper asymptote of an S-curve is often called its
| "carrying capacity". We expect an inflection point about
| halfway toward this point. What do you think the maximum
| capacity of global solar energy is? The total amount of solar
| energy hitting Earth is about 4.4 * 10^16 watts -- 44,000
| Terawatts. If we covered 1% of the Earth in solar panels at a
| meager 10% efficiency, that's 44 Terawatts -- this is a
| reasonable low estimate for the "carrying capacity" from
| total solar irradiance. We're at about 1 Terawatt right now.
| A high estimate (remember, this is the absolute maximum)
| might be 10% of the Earth at 20% efficiency -- 880 Terawatts.
| Of course, if we run out of space on Earth, there's always
| more space in ... well, space.
|
| Another "carrying capacity" could be the materials needed for
| production. As TFA illustrates, we have enough different ways
| of producing solar panels that we are not anywhere near
| maxing this out either.
|
| So I think there's pretty good justification to think we're
| still at the very early part of this S-curve.
| tnel77 wrote:
| This gives me hope! Thank you for sharing!
| addaon wrote:
| > So... 1,2,4,8,16,32,64,128,512,1028, 2056 terawatts in 30
| years?
|
| What did 256 terawatts ever do to you?
| beanjuice wrote:
| My two cents having formerly worked in perovskites trying to
| upscale the process:
|
| Perovskites are exciting (or were exciting) because they have a
| high theoretical efficiency, are relatively simple to prepare,
| and the "worst" component in them is lead (an incredibly abundant
| material). The big problem with them is that they are famously
| horrifically unstable in ambient conditions.
|
| Roll-to-roll processing means that you can fabricate them in mass
| scale. Ambient means that they claim to have solved issues like
| working in glovebox conditions.
|
| Even if the price of solar panels has come down below labor, the
| fact that they are produced from rare earth minerals goes (in my
| opinion) underreported.
|
| Consider the relationship between perovskites and multi-junction
| solar cells similar to the comparison between sodium and lithium
| ion batteries. Lithium will always have a higher capacity, but
| sodium is so abundant that for many applications it just doesn't
| matter anymore.
| hinkley wrote:
| Do we not have lead free perovskites now?
| philipkglass wrote:
| Tin based perovskites have been studied for almost as long as
| the lead based ones but they have been less efficient and
| much less stable. Work continues to increase their efficiency
| and stability, e.g.:
|
| "Efficient tin-based perovskite solar cells with trans-
| isomeric fulleropyrrolidine additives" (2024-01-29)
|
| https://www.nature.com/articles/s41566-024-01381-7
| KennyBlanken wrote:
| Solar panels "produced from rare earth minerals" is "under-
| reported" because _they are not made from rare earth minerals_
| , and further: the minor metals they _are_ dependent upon are
| byproducts of refining base metals, ie there isn 't much
| additional impact from using them; we already make them.
|
| I'm not really sure how someone who supposedly worked in solar
| panel research would think rare earth metals are used in solar
| panel construction.
|
| Solar panels have decades-long lifespans (their rated lifespan
| is based on when they drop below 80% efficiency, not when they
| become useless), there's a growing recycling chain to sell
| complete aged panels to other markets (typically underdeveloped
| nations where daily equivalent hours of solar are very high and
| land is plentiful so efficiency doesn't matter), and the panels
| themselves are highly recyclable for the materials to make new
| panels.
|
| Ever notice how the people 'concerned' about the environmental
| impact of mining rare earth minerals, which go into durable
| goods that are highly recyclable/recoverable, don't seem to
| have a problem with oil drilling, fracking, coal strip mining,
| etc - for something that is usable once, maybe twice?
| refulgentis wrote:
| This is true: i.e. they use _rare_ metals not _rare earth
| metals_.
|
| On HN, I hope we can share a correction like that
| respectfully: after all, they gave good info, except for a
| one-word slip of the tongue.
|
| The critique seems to extend beyond correcting that error,
| becoming confrontational, questioning motivation and honesty
| with phrases like "supposedly worked in." and the long bit
| defending lifespan and enviromental impact against people who
| "don't seem to have a problem with oil drilling, fracking,
| coal strip mining, etc" - they didn't even touch on that
| subject.
| beanjuice wrote:
| Thank you for responding, I agree with your points, I did
| indeed make a mistake.
| sholladay wrote:
| Let's make sure they use little to no lead first before we deploy
| them to homes all around the world.
|
| https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9860350/
| fbdab103 wrote:
| Wondering if anyone could help shore up my understanding or point
| out a resource to get me a better handle on this.
|
| Using the solar maps from here[0], you can find the kWh/day/m2
| for the US. If I am in a say 5.7 kWh/day/m2 region and I have 1
| m2 of a 20% solar efficiency panel, does that mean I would get
| 1.14 kWh usable out the other end? Or is it 20% * X% horribly
| lossy conversion factor?
|
| If I want to math out 11kWh/day in the 5.7 region, back
| calculating would put me at requiring 9.6 m2 of panels (11 / (5.7
| * 0.2). Again, if there is a horrible lossy conversion factor,
| that would just go into my denominator, correct?
|
| Or am I missing something entirely? I tried to use this
| calculator[1], but I could not recapitulate the numbers they were
| generating.
|
| [0] https://www.nrel.gov/gis/solar-resource-maps.html
|
| [1] https://pvwatts.nrel.gov/
| flavius29663 wrote:
| The map shows solar resource, irrespective of the technology
| you're using. For example, you could be using heat collectors
| that would capture closer to 100%. To keep things simple, for
| back of the envelope calculations, you can imagine 1kW per
| square meter. Subtract cloud coverage, night hours and then
| multiply with 0.2 for PV panels efficiency.
|
| If you want 11kWh/day, you need: (5.7 * 0.2) * Y = 11, so Y =
| 10 square meters. You can double check this: 10 sqm should have
| about 10KW of solar potential energy, but with PV efficiency
| you're getting about 2KW, so to reach 11kWh, you need 5 good
| hours of sunshine on average.
| philipkglass wrote:
| You'd be able to generate 1.14 kWh at the panel level if you
| kept the panel pointed directly at the sun throughout the day
| [1]. This is called "2 axis tracking" and it was sometimes used
| for solar farms when solar panels were much more expensive. Now
| that panels are much cheaper, 2 axis tracking has practically
| vanished from the market. The added expense and mechanical
| complexity isn't worth it. Single axis tracking, where the
| panels just rotate to track the sun from east to west, is still
| popular in large solar farms. It captures more sun than leaving
| the panels stationary but has less complexity than 2 axis
| tracking.
|
| For a rooftop solar panel, you're not going to have any sort of
| sun tracking. The lack of tracking will reduce your output at
| the panel level. You will also lose more output if dust,
| debris, and bird droppings don't get cleaned away regularly.
|
| You also lose some energy when the direct current electricity
| from your panels gets converted to alternating current in the
| inverter. How much loss depends on the inverter and how heavily
| loaded it is.
|
| The NREL tool you linked says it's designed for "homeowners,
| small building owners, installers and manufacturers", which
| implies that it's for rooftop systems. It includes estimates
| for those loss factors I mentioned above, which is why I expect
| that it falls short of the number you calculated.
|
| [1] EDIT: I forgot another significant factor: temperature
| coefficient of performance. A panel gets its efficiency
| measured at "standard test conditions" which include a moderate
| (near room temperature) panel temperature. Panels lose some
| efficiency as they heat up, which means that they don't perform
| as well as you might naively expect in the middle of the
| summer. The loss varies by panel technology. The very best
| conditions for panel output -- where they actually _surpass_
| reported efficiency -- is "bright sun but cold air," like noon
| on a freezing cold day with clear skies.
| fbdab103 wrote:
| So, the bottom line is that the simple kWh/day/m2 * panel
| efficiency * m2 of panels should be within the theoretical
| ballpark of generation, but the real world is a harsh
| mistress and will undercut you.
|
| On that calculator resource, they provide a monthly and
| hourly spreadsheet, but even with the more detailed numbers,
| I was still failing to corroborate their presumably much more
| sophisticated modelling which accounts for other losses.
|
| Thanks. Just spit balling numbers and trying to see what
| things look like.
| naasking wrote:
| > which include a moderate (near room temperature) panel
| temperature. Panels lose some efficiency as they heat up,
| which means that they don't perform as well as you might
| naively expect in the middle of the summer.
|
| This is why vertical solar panels are becoming a thing, the
| additional cooling benefits increase output up to or beyond
| the optimal angle to the sun, and the better cooling also
| prolongs their life.
| avhon1 wrote:
| The "System Losses" breakdown shows the various additional
| factors they are derating the system by. The figures seem
| reasonable enough, and give an additional loss of 14%.
|
| I put in my own address, which is in the 4.0-4.5 kWh/day
| region, and set the DC system size to 1 kW, which corresponds
| to 6m2 of panels (courtesy of their rooftop calculator). The
| NERL website estimated that such a system would yield between
| 2.45 and 6.48 kWh/day, with an annual mean of 4.71 kWh/day.
|
| That works out pretty close to what the map indicates for my
| region: 4.5 kWh/m2day * 0.2 conversion factor * 0.86 losses
| factor * 6 m2 of panels = 4.64 kWh/day
| fbdab103 wrote:
| Super appreciate your reverse calculation. The downstream 14%
| loss still is an easy enough fudge factor to use for a
| plausible output number.
| Animats wrote:
| Roll to roll amorphous silicon solar panels go back to the
| mid-2000s.[1] Those were commercial products, and, at the time,
| not much more expensive than rigid cells.
|
| [1] https://en.wikipedia.org/wiki/Energy_Conversion_Devices
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