Comment by beanjuice | Hacker News Reader

Comment by beanjuice | Hacker News Reader

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.

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?

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.

Thank you for responding, I agree with your points, I did indeed make a mistake.

Which rare metals do they use? Silver for contact wires? If silver supplies were inadequate (they're not) these could be substituted for with copper, if a barrier layer was included between it and the silicon.

Maybe indium in ITO for those fancy transparent front contacts. Or tellurium in CdTe, supposedly still costeffective compared to “thick” Si cells. I would still give GGP a break it can be tricky to venture even small steps outside ones specialty these days

And, maybe in the future, gallium as a dopant in silicon cells, since it doesn't experience nearly as much light induced degradation as boron does. But dopants are used in very small amounts.

I think some power electronics uses europium silicide (or was that erbium?) as a gate material, so maybe in inverters? Again, the quantities would be small.

Do we not have lead free perovskites now?

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

Which rare earth minerals go into solar cells?

No rare earth minerals are in solar cells. This is a famously bullshitty meme that was being propagated by Michael Shellenberger.

A simple search of the 'net will answer the question far better than this attack on Shellenberger. It will show that rare earth minerals can be used in PV panels as doping elements. Interestingly enough it is especially Perovskite PV cells which seem to benefit from the use of these additives [1,2]:

(1) Recently, use of rare earth (RE) ions doped nanomaterials in PSCs, has been identified as an effective means to address the aforementioned issues by expanding the range of absorption spectra minimizing the non-absorption loss of solar photons, enhancing light scattering and improving operational stability.

(2) Rare earth ion doped nanomaterials can be used in perovskite solar cell to expand the range of absorption spectra and improve the stability due to its up conversion and down conversion effect. This article reviews recently progress in using rare earth ion doped nanomaterials in mesoporous electrodes, perovskite active layers, and as an external function layer of perovskite solar cell.

[1] https://www.sciencedirect.com/science/article/abs/pii/S10020...

[2] https://www.sciencedirect.com/science/article/abs/pii/S13877...

That's just in the lab. If you buy PV modules right now the cells will not be doped with rare earth elements. And almost everything demonstrated in the lab doesn't progress beyond there (which is fine; that's how technology R&D works.)

I think the closest one could come to making the "REE in solar" claim make sense would be decoloring agents for the glass. Cerium could be used for this, but I think manganese is cheaper.

Cerium is common in solar coverglass used in space, but I'm not sure I've heard of it being used for terrestrial applications.

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