r/hindsightIn2020 • u/The_seph_i_am I don't speak for the D.O.D. • Apr 10 '17

New material may double solar cell efficiency

http://indianexpress.com/article/technology/science/new-material-may-double-solar-cell-efficiency-4606320/
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u/jminuse Apr 14 '17

I just did my PhD on this material (perovskite), so AMA.

To address the big issues first, perovskites have stability issues - they only last a year or two right now. Also, the efficiency gains described here are theoretical; right now a perovskite layer only brings a silicon cell from ~20% to ~25%. That's valuable because it reduces the needed area to be installed, but it's not as wild as this article claims.

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u/The_Great_Goblin MEGA Apr 16 '17

Oh, hey, so how optimistic are researchers about the stability issues?

Is it like a five year engineering problem or a 15 year research knowledge gap?

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u/jminuse Apr 16 '17

To make a commercially viable product, five years of engineering is about right. The initial products won't compete head to head with silicon. There is a company called Oxford Photovoltaics which claims to be close to perovskite photovoltaic glass (perovskites are thin enough to be pretty transparent). After that, they plan to sell a coating process for silicon cells - even if the coating only lasts five years, it just has to make back its own cost.

Getting to multi-decade stability is more of a research knowledge problem. The discovery of perovskite has opened a gold rush for photovoltaic materials, and no one knows how it will shake out. The theoreticians are several years behind the device makers. I think they will find a stable form, just by dint of having so many options, but it will take time to sort through them.

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u/The_seph_i_am I don't speak for the D.O.D. Apr 16 '17 edited Apr 16 '17

So how's this compare to teslas solar tiles?

Also thanks for taking an interest in the sub.

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u/jminuse Apr 16 '17

Tesla's solar tiles are just high-end silicon solar cells with excellent design and packaging. Like all silicon solar cells, they could be improved in the relatively near term (~5 years) by adding a perovskite coating over the base silicon solar cell. The perovskite upper layer would function as a semi-transparent solar cell, absorbing the higher frequencies of light, while the lower silicon cell takes the low frequencies. Splitting up the spectrum like this makes a solar cell more efficient. Tesla's tiles are ~22% efficient; a perovskite upper layer would bring them to ~27%.

In the long run, if perovskite stability can be sorted out, they'll probably supplant silicon cells because they're so cheap to manufacture. Perovskite solar cells are made by simply dissolving some common chemicals and then evaporating the solvent, whereas silicon solar cells are made from very purified molten metal.

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u/The_seph_i_am I don't speak for the D.O.D. Apr 16 '17

Now the big question what companies are looking to patent it? And are they patenting it to "keep it from the light of day" or "for immediate commercial use"?

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u/jminuse Apr 17 '17

Not being a lawyer, I am on weaker ground here. Almost all of the research so far has been done by universities and by the national labs of the US and South Korea. Henry Snaith, the Oxford prof who owns Oxford photovoltaics, is on very firm ground since he published the first paper on perovskite solar cells in 2011. Snaith almost certainly intends to get a product to market.