The science is rather sound on this; melanin has been shown to produce a photosynthesis effect with ionizing radiation. Incidentally, this likely means the solar panels would actually be able to work at near maximum efficiency on partially cloudy days, even on a lightly clouded day it should still work well.
It generally takes much less water to deflect visible light and reduce the efficiency of a silicon solar panel than it takes to absorb the UV that is producing power through the melanin.
What I believe is important here is the melanin. If an efficient and stable way is found to manufacture a melanin-based solar panel, it could be used in a wider range than many traditional solar panels. I suppose the ideal would be to produce a traditional solar panel that is transparent to UV, allowing it to be caught in a melanin-based solar panel. In theory you could double the power output of a solar panel and extend its power production into cloudier periods.
"It generally takes much less water to deflect visible light and reduce the efficiency of a silicon solar panel than it takes to absorb the UV that is producing power through the melanin."
I'm confused by this statement. I'll try to clarify.
Melanin's absorption spectrum can be found here: http://www.cl.cam.ac.uk/~jgd1000/melanin.html
As you can see, it has high absorption from 300nm-700nm which is in the UV-Vis range.
And sorry to nitpick, but nothing deflects light. Light is absorbed, transmitted, and emitted. If it is emitted in the direction from which it came, its called reflectance.
Light can scatter (Rayleigh scattering, Thompson scattering), which does not involve an absorption/emission event (unless you are talking about resonant scattering for example in the Lyman Alpha line).
That's how clouds work. The albedo of clouds is very high, so little is absorbed. Nevertheless, the small water drops scatter the light.
> And sorry to nitpick, but nothing deflects light. Light is absorbed, transmitted, and emitted. If it is emitted in the direction from which it came, its called reflectance.
Sorry to nitpick even further, but IIUC the angle (not the direction) of reflection equals the angle (not direction) of incidence.
It's similar phenomena. When light impinges on a material it is absorbed. Electrons in the ground state are lifted into a higher state, and after a very short time (nanoseconds) they relax, re-emitting that light. That light goes in every direction possible, but the light that you perceive is that fraction of the light that is emitted back in your direction...or in a refracted direction.
I do not believe that this is how refraction works. It would imply that light of frequencies other than those corresponding to the bandgap energies of the material would proceed unrefracted, or be absorbed. Furthermore, it would render coherent light incoherent, since nanoseconds are very large compared to the frequencies involved in visible light, and this incoherence would result in the light being re-emitted in every direction, not a particular refracted direction. In short, although the phenomenon you are describing is real, it is very different from refraction. It is phosphorescence and fluorescence.
Every material has optical and electrical properties. Light is always interacting with materials. The difference is that you're not applying a load. Or maybe you are and its just small...I'm not too familiar with biological materials. Either way, you need to complete the circuit and channel the electron flow.
The circuit is normally completed at a scale where you can't use the electricity generated by the photo-electric effect.
To make is useable you have to somehow collect the electrons before they fall back to their base state. For that you need a semiconductor, which effectively creates a barrier across which the electrons can not travel back.
The little metal wires that are silk screened on to solar panels collect these free electrons and transport them to the edge of a photocell, where they can be used to drive a load on their way back to the substrate from which they've been liberated.
I have no idea of how melanin works as a photovoltaic, but if it indeed only converts UV light then the power output will be severely limited compared to visible-light cells, because the Sun only emits a very small part of its luminosity in the UV.
"Attention grabbing"? It's a tabloid paper. That's what tabloid papers are for. As for "wildly inaccurate", it simply has quite a strong bias, but so do lots of papers. The Guardian is no less partisan.
I wouldn't buy a copy of the Mail, but I'm tired of reading fatuous name-calling of this sort from people who've never read the paper.
The "faceless aliens" story is about real people walking around with masks on. The story itself points that out: Close inspection of the pictures rules out an alien invasion - small perforations around the eye areas of the masks allow the people beneath to see the world outside.
It then goes on to speculate that they're part of a viral marketing campaign or celebrities in disguise.
Lightweight and lowbrow, sure, but they aren't just making up tabloid lies.
The news in the Mail might be a bit hyped but it's not "wildly inaccurate". I don't read it either, and wouldn't, but it's not exactly The Daily Sport.
So, you wouldn't buy a copy and yet you claim others have never read it?
My parents buy it, so I've read it fairly often at their house, but, no, I wouldn't buy it myself. So yes, I have read it on many occasions, while most of those who bash it do so without having ever read a copy.
To put the guardian and the daily mail in the same column is doing serious injustice to the guardian.
I didn't put them in the same column: as I said, the Mail is a tabloid. All I said is that both are heavily biased, which is true. Each writes with its own audience in mind: Guardian readers won't like what's written in the Mail, and vice-versa. Accusations beyond this, such as yours of "wildly inaccurate journalism", are more exaggerated and sensational than any Mail headline.
I'm impressed in principle, but I'll believe it when I see an article in The NY Times, The Washington Post, or The Economist. That those reporters have chosen to ignore it gives me cause for concern.
It looks like just a small amount of hair on there. I wonder about the watts per area.
I bet it would take a massive amount of surface area compared to regular solar cells.
It's a very cool demonstration/proof of concept, but it's not practical for actual use. (But might have a niche in places where other sources of electricity are non-existent.)
I get the feeling a windmill and water tower might be a more durable, effective and all-around useful solution for those areas.
Anyone who found it cost effective to wind human hair around terminals by hand every few months likely has more basic needs to be met than simple electricity.
The news is only as good as it's source. I am sceptical about the claim. Would love to see this news in science magazines like New Scientist or Scientific America, before buying it.
Hardly, they're reading DC not AC, the ballast will induce a few milliwatts (at the max) in the wires and at 50~60HZ this will likely be within the margin of error on a hand-built solar panel anyway. (Ed: The electrical meter likely wouldn't detect the interference as AC is generally self-cancelling interference on a DC line, unless diodes are in use)
Induction between two wires is exceptionally low. Unless the two copper wires share the same ferrite core, you'll get diddly squat out. Noise in an electrical signal, is very different from noise in power, which would require an actual imbalance in the AC outputs, IE a power plant running at 50HZ and one running at 55HZ will produce a very unstable power supply.
I would have thought the CFL ballast would run in the kHz range, not 50-60 Hz.
The DMM appears to be reading voltage, and its input is probably pretty high impedance, so it may very well be sensitive to the hash from the ballast (the meter's input protection circuits may be rectifying the AC).
Single strands of hair strung randomly around a grid? This cannot possibly be an effective approach. But there's an even easier way to prove it's a hoax -- human hair is not an electrical conductor, and doesn't produce electricity under sunlight. (This takes about fifteen seconds to test for yourself with a multimeter.)
I don't know if the science behind this is sound, so assuming that it is:
According to the article the panels are expected to be manufactured for 1/4 the cost of current panels of similar wattage. But it also says the hair "...lasts a few months", which means that they are much higher maintenance than silicon based panels which last at least 5 years with current designs.
So TCO may be higher for the hair panels, especially if longer strands of hair are needed.
As far as the validity of this goes, I need more hard facts before I can make a decision. Those hair strands aren't packed in there very tightly, so getting 9v/18W out of that panel is fairly unbelievable.
£23 ≈ US$38. At 18W that's US$2.11 per watt. That is indeed about half the price of silicon solar panels last I checked. I have no knowledge of these properties of melanin, so I don't know if this is a hoax.
Price of hair really varies depending on the quality required. If it's being mulched down to make the commercial solar panels, then it would likely cost next to nothing. However if you need high quality, long undamaged strands it's going to cost you, because you're going to be competing with an existing market (wig, mannequin and certain dolls are typically made with all real hair), which will drive prices up significantly.
I believe the ultimate ideal for this would be to make the hair easily replaceable by a person. Quite literally grow your hair X inches long, cut, hold out straight and clip into place. This is likely to be sold out in poorer countries where people haven't handled technology and need a simple way to maintain it. However the countries that would typically require this are somewhat blessed by the near perfect black of their hair, because blond hair has little to no melanin and would be useless, even brown hair would reduce efficiency greatly.
Hey, hey, let's go easy on the "superstition" part, OK? :)
One man's religion is another man's superstition, I guess! And shaving off the hair is pretty harmless, as "superstitions" go -I mean, I got a lot of friends pretty non-superstitious types who shave off their hair here in the valley.
Maybe. The article asserts that, but it says that's the material price. So mass-production will involve paying people for their work (price goes up) and perhaps using less material (price goes down). I was just verifying the calculation, because I found it dubious at first.
About dubiousness: I am also skeptical. It feels almost too good to be true.
As for mass production: it also takes advantage of economies of scale (price goes way down), automation (price goes down), and "side channel" revenue streams -- open your own barber shops/salons and charge half of what others charge.
I think the big issue is that it's easy to do in developing countries, so this could possibly result in a lot of DIY panels. Even if this has no flaws beyond that, I don't think we'll see this appearing on US or European roofs. (Well, apart from the alternative crowd who'd probably flock to Cherokee Hair Panels)
Wonder how long the hair lasts. If you continually have to rethread your panels, valve-style...
Hmmmm... If that works and is going to be used for lighting, then combining it with a pulse width modulator of about 50pc duty cycle should double the supply duration.
It generally takes much less water to deflect visible light and reduce the efficiency of a silicon solar panel than it takes to absorb the UV that is producing power through the melanin.
What I believe is important here is the melanin. If an efficient and stable way is found to manufacture a melanin-based solar panel, it could be used in a wider range than many traditional solar panels. I suppose the ideal would be to produce a traditional solar panel that is transparent to UV, allowing it to be caught in a melanin-based solar panel. In theory you could double the power output of a solar panel and extend its power production into cloudier periods.