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Comment by acchow | Hacker News Reader

FTA: "Commercial solar photovoltaics usually covert 15-22% of sunlight, with a world record of 26.6% reached in Japan in 2016."

And yet your linked chart shows datapoints >40%. What gives?

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Commercial solar photovoltaics typically refer to "standard" silicon solar cells which have efficiency around the 15-22% range. The 40% cells in the graphic are for materials systems that are much too expensive to be commercially viable.

Yep, the very high efficiency cells are typically reserved for highly specialized areas where cost doesn’t matter.. You’ll see Boeing’s name a lot near the top of the efficiency list for the exotic cell types, their lab’s website should clue everyone in to what their main purpose is: https://www.spectrolab.com

They list 31% efficiencies for their cells that can fly today which must be near the limit of commercialization / certification. Still pretty good though, that’s 50% more efficient than a standard panel, and at several $10s of thousands per kg into space, clearly worth it!

28/30% cells are common in spacecraft and have been for more than five years, but they are expensive. A little less than 10k for something like 1 square meter only for the cells wouldn't be crazy.

It looks like Boeing's latest multijunction line ships at 30.7% efficient:

https://www.spectrolab.com/photovoltaics.html#cells_cics

Which seems about right, but what I didn't realize is that they're shipping >40% concentrators too. That's pretty great!

https://www.spectrolab.com/photovoltaics.html#cells_cics

(That last link was supposed to be for the concentrator section at the bottom of that page, but I don't think it's a normal # bookmark)

These cells should be available for everyone and not just the 1%.

These things aren't expensive just for fun. They're usually made of very exotic materials or very difficult to manufacture, hence the prices. They'll go down if they become easier to make.

Although in this case those ultra-expensive cells are being built by Boeing for space use. That no doubt includes a lot of flight certification and similar checks. If you were making a version for domestic use the price could probably be significantly reduced.

That said, they would only make sense in places where space is at a premium so people are willing to pay extra for something a bit smaller. That's not especially common in home use.

This is what NASA could get to power their satellites, at NASA's pricepoint.

Commercial means what you can buy at reasonable prices.

It takes some time from knowing something is possible, experimental technology, like multitouch controlled computers, and companies selling them in the billions, like multitouch being in every Ipad or smartphone.

multijunctiion.

Well, isn't this new device essentially a multijunction organic solar cell? That's what I gathered from the BBC article.

I guess the hope is that they will command less of a relative premium compared to multijunction silicon cells?

Inorganic multijunction devices are very difficult and costly to make, because the materials have to be evaporated into place. Organics in principle can be printed using standard solvents.

Let’s not forget that many thin-film amorphous silicon devices use multiple junctions as well.

The article isn't very good is what.

No. The >40% are "exotic" in some fashion and very expensive compared to what is commercially available. Think of "hero" cells where the best cell from an entire production run is tested or a cell is produced using techniques that are incompatible with mass production. Now, add in tandem (multijunction) on top of that, and you get to >40%.

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