There is a lot of "math play" which at first glance can be confusing. For example, they say 25% more efficient than existing panels. If existing panels are thought to be 20% efficiency on average, you might assume they mean 45% efficiency.
Then when you read that they say make 24% efficient modules, which are 25%+ more efficiency than other panels it sounds like they are saying other panels have -1% efficiency?!?
So what they really mean is if other panels are say 20% efficient, they are 25% MORE of 20... or 0.25 x 20 which is 5 more... so they bump up the efficiency from 20% to 25%, which is 5% "more". See, for someone just looking at a glance without knowing, it would seem like they are going from 20% to 45%, when in fact they are going from 20% to 25%.
Still, it is an improvement, and if it can be made cheaper and saves Silicon then great. But what are they spending the money on, and if they made one of their cells already then where is it, where is the data on the performance of the cell and the actual thickness, how did they do it, and how to they plan to scale it? I'd be more impressed to see an engineer go over that then Bill Nye or a bunch of marketing fluff stuff.
There is a conventionally understood meaning to "62% Cheaper And 25% More Efficient " that doesn't warrant the criticism "math play". I seriously doubt anyone thought they had 45% efficient (in absolute terms) solar cells.
On the other hand if you were talking about sunscreen products going from factor 30 to factor 50 then most people wouldn't realise the reduction in UV penetration was just something like 3 to 4%.
In any case there has been a consistent and incremental series of efficiency improvements and cost of manufacture saving making solar technology more affordable over decades. Why is another one so outrageous that it begets the sort of ignorant tribalism on display here?
Where is the evidence that there is a scam afoot here? So far all I see is opinions and possibly misinformed opinions. Where are the facts?
Here are some facts:
Efficiency
1) Lets give them the best chance of success and assume
they are using mono-crystalline silicon cells.
Per the NREL the maximum efficiency for mono-crystalline solar cells achievable under *IDEAL* lab conditions has been about 25% .
Please keep in mind that these are conditions where a bunch of researchers with pretty much unlimited time and resources made *one cell* .
2) The theoretical upper limit of a silicon solar cell is
calculated to be in the neighborhood of 29.4 percent. This is given to us by pesky things like the laws of physics (see paper).
3) Rayton Solar
claim that their cells are 3 microns thick and
here is where they claim their cells have 24% efficiency4) As uwezi nicely pointed out with references:
Silicon is a bad light absorber because of its indirect bandgap. In contrast to direct bandgap materials like GaAs or Cu(In,Ga)Se2 a 3µm thin silicon solar cell will only absorb about 1/3 of the incoming sun light. With this little absorption a 20+ % efficient solar cell is out of discussion.
http://www.pveducation.org/pvcdrom/design/material-thickness
http://www.pveducation.org/pvcdrom/design/solar-cell-parameters
At least thicknesses around 30 µm would be needed, which in turn are most likely not achievable with the described exfoliation technique, which otherwise is known under the name SmartCut in the semiconductor community.
http://www.sciencedirect.com/science/article/pii/0927024894900086
https://en.wikipedia.org/wiki/Smart_cut
They just copied their idea from a book (nothing wrong with that, but they should have read the whole paragraph):
https://books.google.se/books?id=TpZo_wEeJe0C&lpg=PA110&ots=_9uMHQgDAC&dq=silicon%20smartcut%20solar%20cell&hl=sv&pg=PA110#v=onepage&q=silicon%20smartcut%20solar%20cell&f=false
and one last link to a report highlighting the problem:
http://www.nanophotonicseurope.org/index.php/component/docman/doc_download/8-glunz-photonics-for-high-efficiency-crystalline-silicon-solar-cells
5)Using the maximum theoretical efficiency of the ("best case" thickness) 110micron cell given in (2) and the reduction in light absorption given in (4) and in
T. Tiedje, Yablonovich, E., Cody, G. D., and Brooks, B. G., “Limiting Efficiency of Silicon Solar Cells” it is easy to mathematically show that the claims of a 24% efficient mono-crystalline 3 micron thick solar cell is effectively impossible. And *EVEN* If it was possible (which its not) - there is no way in hell they are able to commercially produce such a thing . *ESPECIALLY* considering where the upper limits of research solar cells (given in (1)) are.
Thus
6)We can see that their claims of a 24% cell efficiency seem *extremely dubious*. Performing the above calculations - the final efficiency they are able to produce is likely to be
at or below the 15%-19% range *AT BEST* (but probably significantly less).
Knowing that, lets look at their other claim , "60% cost savings"
CostAs mentioned earlier
they claim a $0.227 price per watt and a 62% cost savingsSources for the info below:
a)
http://www.trendforce.com/price/pv b)
http://pvinsights.comc)
http://pv.energytrend.com/pricequotes.html1) You can buy equivalently (from our calculations above) efficient solar cells for around $0.205-$0.230 per watt. RIGHT NOW.
2) You can buy
more efficient (simply because they are thicker see calculations above) mono crystalline solar cells for around $0.250 per watt.
Thus: they are either 10% MORE expensive than equivalent efficiency cells or 10% cheaper (at best!!) than more efficient cells.
Conclusion : 1) 24% Efficiency claim - nope.
2) 62% Cost savings claim - nope.
Q.E.D
Bonus RoundI'd like to add that the discussion thus far (both on here and as presented in their marketing material) has focused
on the bare cells . Solar cell
encapsulation is *critical* to the ability of ANY cell to perform and survive .
See this presentation encapsulation from the NREL.
The fact that the cells that Rayton shown below
are not properly encapsulated at all should raise *significant* concern among investors in the company.