Catch up on stories from the past week (and beyond) at the Slashdot story archive

typodupeerror

## Hairy Solar Cells Could Mean Higher Efficiency203

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."
This discussion has been archived. No new comments can be posted.

## Hairy Solar Cells Could Mean Higher Efficiency

• #### Sheeit Negro, that's all you had to say! (Score:2, Interesting)

on Monday May 19, 2008 @04:48PM (#23467810) Homepage
What's really awesome is that PV cells have undergone constant improvement in lab performance for 20 years, but since nothing ever gets put into production, the industry is held in a constant state of "early adoption" and we get screwed like perpetual "early adopters".

Know what would rawk? A 5 year moritorium on new PV cell research so we could get some actual PV cell production going.

• #### Re:Dramatic efficiency improvements unlikely. (Score:2, Interesting)

on Monday May 19, 2008 @05:14PM (#23468046)
solar could maybe provide 10% of our needs at most. it can't supply base load, which is something nuclear can do very well. don't tell the tree huggers that though, they want to continue to live in their dream world.
• #### Re:Nanowires are nice and everything... (Score:4, Interesting)

on Monday May 19, 2008 @05:21PM (#23468106)
Barely related... but as a South Texas resident, I wonder how much less I could run my A/C every year just because of the shade provided by solar cells on my roof? I believe I first used my A/C this year in February, so even a small decrease could be significant over the year.

I also always wondered why people don't advertise how much cooler CFL bulbs are than incandescent bulbs. I replaced 480W of lighting in a bathroom with 72W (replaced 60W clear bulbs with 9W vanity CFLs) and not only is it brighter and the light softer (and thus makes ladies feel prettier when doing whatever it is they do for hours in bathrooms) but it's a lot cooler. And they will pay for themselves in roughly 13 months.

And similar swaps make a really significant difference when sitting under the 5-bulb light that is just above the dining table. A friend of mine used to unscrew some of the bulbs when she did homework.

So basically now I save electricity while saving electricity.
• #### Re:Let me guess... (Score:5, Interesting)

on Monday May 19, 2008 @05:32PM (#23468208)
Remember, solar power is generally available HERE and NOW.

I just invested in a PV system for my house (in sunny SoCal). As a computer geek, I asked our guy if it was stupid to invest, since there always seem to be efficiency breakthroughs on the horizon.

He reminded me that efficiency generally meant "smaller" and perhaps "cheaper". But since my roof was plenty adequate for what I needed, "smaller" wasn't really an issue. Cheaper will ALWAYS be the case, as it always has been.

Don't get frozen by the thought that solar power isn't worth investing in today. It totally is.

• #### Re:Nanowires are nice and everything... (Score:3, Interesting)

on Monday May 19, 2008 @05:36PM (#23468238) Journal
Ahh, but that's because you live in Texas. Residents of lesser states are often concerned primarily with heating a room instead of cooling it. The difference is particularly huge in a batroom with a well-lit mirror, where 300W of heating in a small poorly-ventilated room could send the temperature over 100 in minutes - the CFLs are a glorious change, and available in whatever color temperature suits your fancy.

Now we just need affordable dimmable CFLs for that dining table fixture, and low-wattage CFLs with the same wonderful very-warm color temperature that you get from dimming a 300W floor lamp down to 3W, which does as much as alcohol for making your partner look more attractive. ;)
• #### Re:Let me guess... (Score:4, Interesting)

on Monday May 19, 2008 @05:39PM (#23468296) Homepage Journal

Currently there is no single device that is sensitive to the whole visible spectrum
Then why not have some sort of dichroic reflector pass specific wavelengths to specific PV cell banks?
Good idea, but someone beat you to it [uspto.gov]
• #### Re:Wow, are u clueless or what (Score:3, Interesting)

<(skidmore.22) (at) (osu.edu)> on Monday May 19, 2008 @06:12PM (#23468632)
..and I'll believe it when I see it.

Planned installations chasing incentives are a far cry from power plants installed to meet grid needs.

24h power (storage and retrieval of energy) is unnecessary system complexity when you are not looking to replace the current grid, and at their current level of deployment (nil, pretty much) this is not a concern. You might want to co-fire with natural gas to avoid thermal cycling of your plant like they do at Kramer Junction in CA, but that's beside the point.

Furthermore, there is a strong disincentive to producing 24h, and that is the overnight bulk rate for electricity - maybe $.06/kwh vs more than$.20 at peak when you have the solar resource.

• #### Re:Let me guess... (Score:2, Interesting)

by Anonymous Coward on Monday May 19, 2008 @06:43PM (#23468910)
Not only here and now. I started homesteading in 1979 and been off the grid, but not without power since then -- the tech was already good enough insofar as solar panels go. Batteries, on the other hand...we do OK with what there is. What makes good panels (such as I have) expensive is not the silicon part. It's all the rest, which has made my panels last from then until now, still performing like new -- I couldn't guess the eventual lifetime. All it's going to take is more people putting their money where their mouth is, instead of using theoretical improvements as an excuse to wait forever.

My systems now run a campus with 4 buildings, a large computer network, a machine shop, an electroplating line (not all at once, there's only a couple of us to use it all). Is that finally good enough? Not to the oil trolls, the people who won't pay for power upfront, or who think that if we just tax those other guys enough (and who pays for that, really?) someday soon I'll be able to buy a magic box to clip to the antenna on my Toyota and it will the run on freely available hydrogen...I have permits for all kinds of dangerous things -- but can't even buy hydrogen, evidently in reality it's more dangerous than guns, high explosives, various chemistries...the list goes on.

Don't slashdot me all at once at
www.coultersmithing.com

• #### Re:Wow, are u clueless or what (Score:1, Interesting)

by Anonymous Coward on Monday May 19, 2008 @06:52PM (#23469012)

but systems meant to be installed on top of a residential roof are notoriously bad for needing to be repaired every season, for some unlucky souls...
Your anecdote is stale. It was also retired two decades ago. Modern systems are reliable to the degree of other residential systems. This is due to engineering and manufacturing improvements
• #### Re:Dramatic efficiency improvements unlikely. (Score:5, Interesting)

on Monday May 19, 2008 @07:03PM (#23469088)

solar could maybe provide 10% of our needs at most. it can't supply base load, which is something nuclear can do very well. don't tell the tree huggers that though, they want to continue to live in their dream world.

Just to be contrary: at least in theory, solar COULD supply base-load. All you need to do is integrate the Earth's power grids. Then you'd have a more or less constant amount of current available throughout the grid.

Of course, this isn't practical - even ignoring the political implications, transmission losses would create serious problems. Getting away from AC current and using DC for all grid transmission could fix part of that problem, but that's not likely to happen any time soon.

And yes, you're certainly right about nuclear. Realistically, it's our best option at this point in time. That's one thing that France got right.
• #### Re:Let me guess... (Score:2, Interesting)

by Anonymous Coward on Monday May 19, 2008 @08:50PM (#23469922)
Thank you thank you thank you! I've lost count of the number of times I've heard the "solar is almost ready, but it's only x% efficient, so best to wait a little longer when it'll be cheaper/smaller/whatever" argument repeated over the years. Yes, just like any other technology solar cells will get better as time goes by... so the "don't buy until we reach nirvana in $\lim n \to \infty$ years time" argument can be equally applied to pretty much any technology. Like, say, computers, cars, refrigerators, home theater systems and microwave ovens. So would you indefinitely delay purchase of the items on this list in response to this argument? Of course not! If the technology does the job, then you buy it. This applies to to cars, to computers, to microwave ovens... and to solar cells.
• #### Re:Wow, are u clueless or what (Score:1, Interesting)

by Anonymous Coward on Monday May 19, 2008 @10:23PM (#23470632)
This weekend i am giving a tour of a residential roof top solar thermal system that has been in operation for 20+ years. It only went through one upgrade during that time.

There may have been problems with systems installed back in the 70s but few problems with modern systems.

In China and Europe there thousands of these systems installed and they have proven very reliable.

Not sure why these myths are so persistent.

• #### Effort actualy has to be put in (Score:4, Interesting)

on Monday May 19, 2008 @10:49PM (#23470780)
Nuclear always comes up in discussions like this. The answer for nuclear is to put as much effort into research as is going into solar research - instead the money has gone into lobbying to build antiquated plants. If more research was done pebble bed might be furthur along, accelerated thorium might be at the full prototype stage and synrock might have been developed in less than thirty years. Note that the three major developments come from South Africa, India and Australia on fairly small budgets from begrudging governments - think what the USA could have done on venture capital alone. There should be more to civilian nuclear energy than 1960s white elephants painted green.
• #### Re:Let me guess... (Score:4, Interesting)

by Anonymous Coward on Tuesday May 20, 2008 @03:39AM (#23472522)

Why is it that in any conversation about alternative sources of energy someone will mention Nuclear power as "feasible", "sustainable" or any other optamistic decriptor that, based on a critical examination of nuclear power, clearly isn't the case?
I imagine it's because based on a critical examination of nuclear power, it clearly is the case.

long term isotope storage (or "waste")
The "waste" of breeder reactors consists of relatively harmless elements (like lead) and radioactive substances with short half lives that within days decay into relatively harmless elements. And if you want to argue about breeders generating plutonium then by all means describe a disposal method for the plutonium from decommissioned bombs that guarantees it will never in its 24,000 year half life find its way into another bomb. My way is "destroying" it by using it as fuel in a reactor, which is the same place plutonium generated by breeders can go -- and in that case it can be salted with Pu-240 to ensure it can't be used in bomb making.

considerable CO2 emmissions from the energy used in the production of U-235 for reactor cores
As opposed to the CO2 emissions from the energy used in the production of, well, everything? Solar/wind/whatever included? That is, unless that energy comes from non-fossil sources -- which is the whole point of this exercise in the first place.

CFC's leaked in the actual process are America's Number 1 source of CFC emmissions and are up to 20,000 times more potent as a greenhouse gas than C02.
What is this, the 80s? CFCs were banned more than a decade ago in the US. They were used as a refrigerant in uranium processing just like they were used as a refrigerant in other applications prior to the ban. Now they use non-CFC refrigerants. Welcome to 1995.

S.T.P is revealing itself to be completely viable alternatives to coal based on the capability to store thermal energy long after the sun goes down. That is the whole point of solar thermal power after all.
How is it that you're ignoring the gp's point that solar thermal is hosed when you have a cloudy month? It certainly can't store thermal energy for that long. Forget about "put it in the desert" for the northeastern US. How do you propose to power New York City without its nuclear plants?

Old programmers never die, they just branch to a new address.

Working...