Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Roll-to-roll fabricated perovskite solar cells under ambient room conditions

nature.com

Post reply on HN
Print view View original

61–70 of 112 posts

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#61

Post by jjk166 »

londons_explore wrote: post #7

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.

> 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.

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#62

Post by feoren »

jandrese wrote: post #45
dr_dshiv wrote: post #29

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 consump…

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.

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.

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#63

Post by selimthegrim »

pfdietz wrote: post #22
selimthegrim wrote: post #11

Earlier quoted context omitted.

I wonder what happened to singlet fission cells and other things trying to get around the SQ limit

Still being worked on. https://interestingengineering.com/energy/paderborns-new-sol...

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.

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#65

Post by fbdab103 »

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/

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#66

Post by hinkley »

beanjuice wrote: post #53

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 yo…

Do we not have lead free perovskites now?

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#67

Post by WillAdams »

sandworm101 wrote: post #25
ElevenLathe wrote: post #10

Earlier quoted context omitted.

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.

>> 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 woode…

PEV in metal roofing seems more workable.

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#68

Post by MobiusHorizons »

akamaka wrote: post #41
londons_explore wrote: post #7

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.

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%.

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.

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#69

Post by flavius29663 »

fbdab103 wrote: post #65

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…

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.

Re: Roll-to-roll fabricated perovskite solar cells under ambient room conditions

#70

Post by philipkglass »

fbdab103 wrote: post #65

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…

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.

Post reply on HN