Hairy Solar Cells Could Mean Higher Efficiency

kitzilla writes "Two research groups working independently have come up with what they say are cheap processes for growing nanowires to be used with solar cells. The 'hairy' cells provide a direct path for electrons collected at the panel face to reach an electrode, something which has the potential to dramatically improve system efficiency."

Comments

Re:Let me guess...

[frying_fish]

Slight problem at the moment is band gap, and tuning a semiconductor to have the appropriate bandgap that will cover the visible spectrum. Currently there is no single device that is sensitive to the whole visible spectrum, but there is research into this. This is one of the major reasons for the low efficiency in solar cells.

Re:Let me guess...

[chuckymonkey]

Personally I love solar voltaic panels with a little of that canned cheese on them. On a more serious note, why do people not focus on the tech that we have now? For instance if you want solar the solar thermal systems are pretty cheap to build and have decent efficiency. I just don't get why everyone is so stuck on solar voltaic which is as someone else said in a perpetual early adoption stage when a good chunk of baseline power could be provided by solar thermal.

Dramatic efficiency improvements unlikely.

[BlueParrot]

If I am not completely mistaken "classical" semi conductor cells can reach efficiencies of 40%, meaning that even with perfect 100% efficiency you would get at best a factor 2.5 improvement. Of course, 100% efficiency is an impossibility and thus I think we can safely assume that these cells will never reach more than 80%-90% efficiency, which would be an improvement of a factor of 2 over current technology. Now last estimate I saw was that in Europe solar cells work out to be about 4 times as expensive as wind power (which is itself rather pricey ), so even assuming the 100% efficiency, efficiency gains alone cannot make solar economical.

Add in to this that a large part of the cost of solar is the energy needed to produce the cells, which means that if you get that energy from a more expensive power source, the price of the cells will increase. I.e, if one started to replace relatively cheap generation capacity with more expensive solar cells, then the cost of energy, and hence the cost of the cells, would increase.

It would therefore appear to me that for solar to have a chance to become competitive what is needed is focus on lowering the cost of producing the cells, because the gains from improving their efficiency cannot offset their presently large price, and it appears unlikely that pushing for higher and higher efficiencies will be possible without making the cells more expensive.

Re:Dramatic efficiency improvements unlikely.

[clonan]

Currently availible non-specialty cells (the cells used for space etc are not used for general power) are typically between 5 and 15%.

Therefore getting to the 80-90% range would result in a 5-18X improvment.

Since solar is currently 4X, that means it will drop to .2-.8X of CURRENT power costs.

Now remember that hydro is essentially 100% tapped. Wind has a much more limited range and is already approaching the likley maximum efficiency. Nuclear is great but will take some time to spin up. Oil/natural gas prices are climbing rapidly and coal is becoming more expensive to mine and or clean.

Solar PV provides a great load matching power source that will help reduce an individuals demand on the system even if it doesn't complely remove the need for other power sources as well.

Re:Dramatic efficiency improvements unlikely.

[Anonymous Coward]

Photovoltaics can't supply base load now, but that doesn't that you can't get a solar plant to supply base load. The trick is to instead, use thermal energy. We can store the excess thermal energy overnight to continue generating power in the dark, until the sun shines again. Check it out http://en.wikipedia.org/wiki/Solar_thermal_energy

Re:Dramatic efficiency improvements unlikely.

[BlueParrot]

Currently availible non-specialty cells (the cells used for space etc are not used for general power) are typically between 5 and 15%.

Therefore getting to the 80-90% range would result in a 5-18X improvment.

Since solar is currently 4X, that means it will drop to .2-.8X of CURRENT power costs..

I said 4X WIND POWER costs. Not current power costs. Britain's Royal Academy of Engineering estimates the cost of wind power at roughly 3 times that of nuclear, so even if you achieve 90% efficiency that would put you at roughly twice the cost of nuclear generation ( assuming 15% efficiency for present cells ). Now, to give an idea of how hard 90% efficiency would be to reach, the Sun's average surface temperature is 5778K , meaning a solar cell at 300K could at best reach 95% efficiency without violating the laws of thermodynamics.

That is, ignoring ANY other problems you are closing in on the theoretical limits allowed by the laws of physics if you are to get such efficiencies, and you have to do this without increasing the costs of your cells. Any dust on the cells and you can forget it. Protective glass coating is a no-no since it would absorb in the UV range. Heck, simply finding a material that is reasonably transparent at all the relevant wavelengths could be tricky. Add in to this that you cannot use any expensive/toxic/rare elements, that the cells should have to last for a long time, that they should survive a wide range of temperatures and be able to handle a reasonable level of abuse, and it becomes far from certain that it is even possible to reach 80% efficiency, let alone to do so in the foreseeable future.

Re:Anonymous Coward

[QuasiEvil]

AC's got it right. For those who are TLTRTFM (Too Lazy To ...), what the poster should have said is that they help channel charge carriers away from the junction so that they don't immediately recombine. *That* is one of the holy grails of PV design, and one of the reasons that current production cells are incredibly inefficient.

Wow, are u clueless or what

[Anonymous Coward]

Thermal solar is the lowest costs of all AE except for hydro. At this time, it is the same costs as a recent coal plant i.e. a plant that is cleaner than average. Of course, the solar thermal is clean all the way around.
In addition, it is fairly easy to store the heat in salts and generate during the night. Spain, Arizona, New Mexico, Northern Africa, etc. are all headed in GW size of solar thermal. Spain expects to sell power back to its northern neighbors at a tidy profits. Arizona has a 1/4 GW install going in. In addition, another group is close to building a 1/2-3/4 GW in NM or southern CO (possible to take advantage of 3 different power companies and 5 states incentives).

All in all, the only joke is a fool like you.