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Comment by philipkglass | Hacker News Reader

Very good! There are more efficient multi-junction solar cells in commercial use, but the existing ones use stacked III-V semiconductors and are very expensive, really only suitable for space applications. This record is for a thin perovskite material solar cell on top of a conventional silicon solar cell. Both materials are inexpensive.

The main obstacle to commercialization is keeping the perovskite material stable over long periods of operation. This family of materials is more sensitive to water/oxygen/light than silicon itself, but they need to last nearly as long as silicon for cells used in solar farms and rooftop panels.

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Long term degradation and manufacturer warranty for such is indeed a factor. There's a number of poly and monocrystalline Si 156mm cell based PV modules now which are warranted for something like 83% of their original STC rated output after 25 years. Of course you have to also believe that the manufacturer will still be around in the same corporate form in 25 years and able to honor its warranty.

This certainly may not be the case if you follow PV industry news and are aware of how many PV panel manufacturers have formed as startups and gone bankrupt in the last 8 to 14 years.

edit: the other reply here in the thread asks:

> but can be replaced as a layer every, say, 5 years or so? It's not trivial maintenance, but you have to do some maintenance on the panels anyway

Typical mass market PV panels are cells permanently encapsulated behind glass sandwiched with a back sheet, it is not practical or possible to replace a layer or modify the cells once they're assembled into a panel. The only maintenance done on a series of ground or roof mounted typical PV panels is to wash them.

> Of course you have to also believe that the manufacturer will still be around in the same corporate form in 25 years and able to honor its warranty.

I just bought 26 AEG panels for exactly that reason. They were a bit more expensive but my estimate is that AEG will outlive me so that should be fine. Contrast with many other solar panel producers who seem to go out of business ever five years or so.

Out of curiosity what did you pay for them?

225 euros each; but prices have since been going up considerably due to shortages:

https://www.zonnepanelen-store.nl/aeg-as-m1202z-bhm6-365hv-g...

AEG is just a brand?

It is to me...

https://en.wikipedia.org/wiki/AEG

These panels are produced by AEG Industries:

https://www.aeg-industrialsolar.de/about-us/

A licensee of the AEG brand from Electrolux aka The Solar Solutions Group.

Ah I see what you mean now, that was in the context of that it will outlive me, sorry!

In that sense 'Volvo' is also 'just a Brand', as is 'Audi' and many others. Still, that's what people will refer to.

Maxeon extended their warranty this year in select markets to 40 years, which is pretty cool: https://pv-magazine-usa.com/2022/02/04/maxeon-40-year-solar-...

What is cool is that there are also lots of niche markets between now and that future that can use cheaper, shorter-lived, high efficiency panels.

High altitude drones or EVs are much easier to service than satellites: https://spectrum.ieee.org/new-type-of-unmanned-aircraft-aims...

There are hobbyists making solar-powered remote-control planes that are just barely able to charge as much as they draw at noon on a sunny summer day.[1]

Even a minor boost to efficiency could push this concept from "doable in ideal scenarios as a tech demo" to "useful in the real world as a way to multiply the range of electric fixed-wing aircraft"

[1] https://www.youtube.com/watch?v=xS2iCj-HSqY

Imagine you're a truck driver and the whole top of your trailer has solar panels.

Let's say that truck roof covers about 41.5m² (the area of a standard 53' x 8.5' trailer roof). Let's further assume that 41m² of that is covered with PV panels. Using current technology (~21% efficiency silicon cells) and assuming standard irradiation of 1000W/m² this roof would produce ~200W/m² for a total of ~8.2kW. Add a 40' trailer (~31.5m² roof area, ~6.2kW) for a total of ~14.4kW. Using 31.5% efficient cells would raise this to ~22.7kW. Taking the newly releases Tesla semi as an example (~1 kWh/km, ~900 kWh battery pack) this would add about 14 km of range per hour using current cell technology or about 22 km per hour using these new cells. Assuming an average road speed of 80 km/h this would extend the range of the vehicle by up to ~25% for the new cells, ~18% for current cells during daylight hours with standard irradiation and no shading.

>Let's say that truck roof covers about 41.5m² (the area of a standard 53' x 8.5' trailer roof). Let's further assume that 41m² of that is covered with PV panels. Using current technology (~21% efficiency silicon cells) and assuming standard irradiation of 1000W/m² this roof would produce ~200W/m² for a total of ~8.2kW. Add a 40' trailer (~31.5m² roof area, ~6.2kW) for a total of ~14.4kW.

So you're now pulling two trailers but using the watts/km for one. Also your panels will be fixed to the roof and not tracking the sun. you aren't going to get near 30% for them.

First you can cover the truck and actual trailer with panels just fine. Intermodal shipping containers are designed to be stacked and include heavy duty attachment points. https://en.wikipedia.org/wiki/Intermodal_container#/media/Fi...

Second, you aren’t limited to the top of a vehicle, covering the sides is viable and makes up for the sun not being directly overhead.

This depends on the load and on the veracity of the data given by Tesla. A load of styrofoam - which is used in construction, just look what goes under the on- and off-ramps of bridges - doesn't weigh all that much after all. Also, this was not an attempt at with 100% accuracy calculating the range effects of PV panels on the roof - notice the liberal use of the '~' sign and the fact that nearly everything is approximated and rounded down. Did you not notice?

What about if the Perovskite degardes, but can be replaced as a layer every, say, 5 years or so? It's not trivial maintenance, but you have to do some maintenance on the panels anyway, so maybe it's practicable. And the price of replacing a detachable layer should be a small fraction the price of the original panels and installation.

These layers are wafer-thin. Don't think you're going to be able to scrape off the perovskite and reapply it in situ.

https://www.helmholtz-berlin.de/pubbin/news_datei?did=15064

Even if the degradation could be repaired (e.g. after five years, restore a 28% panel to 31% efficiency), at grid scale, does it make financial sense to do the maintenance instead of replacing the panel when it falls below X%?

Would be a shame to waste all the rest of the product just for numbers sake.

It may not need to be wasted. There’s currently a price floor on used EV’s with degraded batteries because they can be used for home energy storage after their useful road life.

There could be a solid secondary market 20 years from now for panels that have dropped to say 20% efficiency where the surface area to yield ratio isn’t a factor (rural areas I would guess).

"There could be a solid secondary market 20 years from now for panels that have dropped to say 20% efficiency"

Current drop down to 70% output is roughly 30 years. These panels won't go anywhere for a long time.

It would need to go to a clean room. And accessing the top lager is at odds with bonding the top glass well enough go protect it.

Methinks a better strategy would be trying to make them keep >17% efficiency even if the perovskite fails and just treating it as a temporary bonus for the early movers. Still sounds hard to manage the voltages as it fails though and would require a different strategy for the busbars even if it were viable.

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