A Step Closer To The Optimum Solar Cell

An anonymous reader writes "Besides cost, solar cell efficiency is the second most critical criteria. Scientists from Berkeley Lab and other institutions, have announced a new solar cell material that may be able to achieve an extraordinary efficiency of about 50 percent -- twice the amount of the current record holder."

Comments

This is the last you will hear of this

[AtariAmarok]

Ah, an efficient solar cell. This is the last you will hear of this! Halliburton and Big Oil will immediately buy the patent and sit on it, just like they did the antigravity saucer, the 300 mph carburetor, cold fusion, and Skynet microchips from the future. Save your cache while you can!

interesting story, dependance on crystal growth

[ubiquitin]

In 1999, Walukiewicz and others at Berkeley Lab were working with solar-cell designers at DOE's National Renewable Energy Laboratory, who were trying to build a three-junction cell. The NREL researchers inadvertently created the first photovoltaic semiconductor with a split band gap. But at first they didn't realize it.

"They needed a new material with a 1-eV band gap and a crystal lattice structure that matched the other layers of the cell," Walukiewicz explains. "They used gallium indium arsenide nitride alloys in which just a little nitrogen could achieve the desired band gap, and an almost perfect lattice match."

Since the band-gap reduction was unexpected, Walukiewicz set out to find out how it worked. The answer, it developed, was that the few atoms of nitrogen, which are much more electronegative than the host atoms (much more strongly attractive to electrons) produced a narrow energy band of their own, splitting the GaInAs conduction band into two parts. The gap to the lower of the two conduction bands was the desired 1 eV.

In the case of GaInAs, other characteristics of the split bands made for a poor solar cell material. Nevertheless, Walukiewicz and his colleagues continued to investigate the phenomenon and developed a model of the split-band phenomenon known as "band anticrossing."

...

Yu admits that forming highly mismatched alloys is "challenging from a crystal-growth point of view," but there is hope that crystals can be grown epitaxially (the growth on a crystalline substrate of a crystalline substance that mimics the orientation of the substrate). One good sign, he says, is that Japanese researchers have already grown thick oxygen-doped crystals of a related material, zinc selenium.

...when I see it

[samael]

I used to jump for joy whenever I saw things like this.

But experience generally showed that Breakthrough X which would produce cheap power/double battery life/allow 5 terabytes in my computer never actually arrived at the market.

I'm still waiting for holographic storage from 10 years ago!

Re:...when I see it

[julesh]

Largley because the incremental process tends to catch up with it before the new idea becomes commercialised.

That's what happened to all the funky things we tend to hear about. We don't all have massively parallel computers because Intel etc didn't all get stuck at 4-500MHz as was predicted some time in the mid 90s.

We don't have holographic storage because, quite frankly, it just ain't worth it when magnetic storage can pack hundreds of gigabytes in a device that is, honestly, about as small as you really need it to be.

If there was a demand for these items, even a perceived one, they'd get produced. But there isn't.

Now, a 50% solar cell...?

Solar energy . . . the big picture . . .

[StateOfTheUnion]

Though a lot of the green crowd have been big proponents of solar cells, solar cells are pretty nasty beasts containing gallium, tellurium, and other heavy metals and nasty components . . . manufactuering them also produces a significant amount of nasty byproducts and waste.

One things that I've never seen is the lifetime and disposal costs of solar cells . . . that never seems to be factored into the so called "solar renewable energy" equation.

Re:Solar energy . . . the big picture . . .

[Infinite93]

The last issue of HomePower www.homepower.com contains a list of RE myths 'debunked'.

The ROI (for retail and manufacture cost) and the Enviromental impact of production is addressed.

Granted the source is an RE magazine, but they do list references on some of the studies if you want to follow up.

Re:Solar energy . . . the big picture . . .

[raygundan]

The panels you can buy and use for your house today have a 3-4 year energy payoff. (ie, they make an amount of energy equal to what was put in to them in production) They last in the neighborhood of 20-30 years.

There are some nasty chemicals required for production. The total environmental impact, however, is significantly smaller than obtaining the same lifetime amount of power from any other source available. The waste produced by a similar amount of power from coal, nuclear, gas, etc... over a similar lifetime is significantly larger.

The pollution only happens once, for 20-30 years worth of power. The pollution from any other option doesn't stop unless you stop using it.

Re:Solar energy . . . the big picture . . .

[ttfkam]

I find it odd that the first page says "Myth: Solar living means sacrificing conveniences," while later on it says, "A PV system provides the required electricity. This type of design is not the norm by far--it's just a little too expensive
up front for most people--and it might require the owners to put on a sweater indoors a few times a year." Turning up the heat when you're cold is a convenience. Having to put sweaters on, however simple and beneficial a solution it may be, is NOT a convenience. Hint: If you are forced to seek an alternative, it is not as convenient.

Myth: You can't use solar energy in far northern latitudes.

When it's sunny, yes, you can use it in northern latitudes. What happens during the rainy season? In many northern states, the rainy season is at least half the year. Go on battery the whole time the sun isn't visible? What happens if (when!) the battery goes dead? Americans used

And let's discuss cost. The brochure you presented states that costs are so bad. Last I checked, good solar panels for the home were upwards of $30,000. If you are already paying for a new house, the extra cost of setting up solar is marginal. For folks who are just getting by (everyone with kids in college), $30,000 just isn't there. Costs from environmental damage where we don't immediately see the price tag? That's fair. Absolutely that's a fair statement to make. Then again so is saying, "What about the hidden costs of completely ripping out an established infrastructure in favor of a new one?" Isn't that fair too?

The idea is to minimize the impact of microhydro by following some simple rules. Always leave enough flow in the stream bed for aquatic life. If migratory fish use your stream, make sure that they and their fry can swim past our diversion, and cannot be drawn into the enstock intake. Always put the diverted water back into the same stream bed in a way that does not cause erosion.

Once again, a fair statement. However how is microhydro going to handle the macro scale when you (a) can't pack them closely together and (b) cannot disrupt the normal activity of the surrounding water? Put more in to get more energy? Remember the 1st Law of Thermodynamics. As it is not created nor destroyed, if you use a sufficient amount of energy in one system, that amount is removed from another system. Environmentally sound? Reducing the energy by a significant amount would be environmentally sound? Most of the world's creatures live at or near a coastline. Carefully consider whether or not you want to mess with this substantially.

Nukes produce nuclear waste, and even after spending billions of taxpayer and ratepayer dollars, no acceptable disposal solution has been brought to the table.

This one kills me. First of all, the term "nukes" usually refers to "nuclear weapons." The requirements for nuclear power are dramatically different from those of bombs. You might as well assert that electricity should be banned because electric chairs are made. It has no place in a power generation conversation. Second of all, there are nuclear reactors such as IFR (Integral Fast Reactor) which were designed specifically to address critics' problems with nuclear. It does not rely on coolant, computer control, or human interaction/intervention to prevent accidents; Safety is dependant upon natural phenomena and the laws of physics to operate. The working prototype for IFR conducted a series of tests where coolant was shut off and all of the usual precursors to a meltdown were put into place. No damage. No leakage. Nothing but a safe, controlled shutdown -- without human or computer interaction. This is not hypothetical. This is historical fact. In fact,

The only equation that matters

[Dr. Bent]

When it comes to adoption of solar power, there's only one calculation that really matters:

C = Cost of installing solar panel
R = Revenue generated (or money saved) per year
M = Maintainence costs per year

(R - M) >= C * 20%

In plain english, when you can get (somewhere around) a 20% return on investment from installing a solar panel, you'll start to see them on top of office building, parking garages, and just out in the middle of open fields, soaking up money.

Until then, solar power will be a technical curiosity for use in special situations (outer space) and for those with a political agenda.

Re:The only equation that matters

[PrinceAshitaka]

this equation matters if you are planning on investing in a solar power plant. I would believe that there is a market for solar powqer for people that would like to live off the grid. unlike nuclear or coal power it is plausible to have a solar power generator for a house and a neiborhood.

Re:The only equation that matters

[SB9876]

The fact that most people miss is that solar cells have started to push past this goal. They now take less energy to manufacture than they capture in their lifetime (always a bonus), and the cost per kWh is pushing down to 2-3 times grid electricity. Given that solar cells have demonstrated a steady decline in cost for the past few decades, chances are good that we'll start seeing large scale adoption in the next decade.

There's also other factor encouraging the use of solar cells. For one, they're much more durable. There's some cells now that can be used rdirectly as roofing tiles where you can put nails through them and walk on them. They aren't the best panels out there but the ruggedness factor is attractive. Also, most power companies now let you sell off excess capacity back to the power grid these days. That development alone can make solar cell arrays in sunny areas pay for themselves in 10 years or so.

Unfortunately, I live in Seattle, land of little direct sunlight and no steady wind. Renewable energy for me is out until those solar cells get another 50% decline in $/kWh.

Re:Something wrong with nuclear power? Oh yeah...

[Councilor Hart]

t is extremely expensive and dangerous,
If I am not mistaking, nuclear power is the cheapest.

A bucket of fission waste under your bed, or a bucket of coal.
Don't compare these things. The first is a waste product, the second is the raw material.
The choice should be between a bucket of fission waste and a room filled the ashes and gasses that resulted from burning coal. I am not sure what would kill you first.

I don't want either of them. But the fission waste can be stored and handeld. I a century or so, we might find a solution for it. The gas on the other hand goes in the atmosphere. You try getting it out. It too might be possible in a century. At least with fission waste the poles don't melt and the climate doesn't change. Although I do have to say that the sun is also partially responsible for a temp-rise.
I don't understand the problem people have with fission. Sure it aint pretty, but it's the best we have so far.

Re:The Socialist solution

[Smidge204]

Under Socialism, R is also 0, but M might not be. You pay for it alright, just not directly.

So under Socialism there is *no* incentive to use them other than political adgendas.
=Smidge=

Re:Something wrong with nuclear power? Oh yeah...

[dbIII]

If I am not mistaking, nuclear power is the cheapest.

Sorry, you are mistaken. Perhaps Thatcher didn't build any more nuclear plants because she was a raving greeny (for those who don't know any recent history, Thatcher was a long way to the right), not becuase of the enormous losses of British Nuclear Fuels. Nuclear power is only cheap if you cook the books by not counting subsidies - it's a very expensive way to boil water.

The choice should be between a bucket of fission waste and a room filled the ashes and gasses that resulted from burning coal. I am not sure what would kill you first.

This is just silly, enough of either will kill you - gas at a few hundred degrees will certainly burn, ash will bury. The nearest office building to you may well contain a lot of coal ash used to make lightweight concrete - the majority of ash is silica in some form or another. Suphur and Nitrogen oxides are not good things to be released, which is why coal fired plants have "scrubbers" - the NOx and SOx is dissolved when the hot gas bubbles through water. It's not an expensive technology at all and has been in use for decades in most of the world. Carbon dioxide is the problem, but nuclear power is still just a 1950's white elephant used as the nice side of nuclear weapons. There are a lot better things to do with radioactive materials than boil water - it costs a huge amount to contain a process like that. Don't blindly believe the advertising agency line for nuclear power - "clean" is not the word that should be used for anything that will kill you on contact or in close proximity.

But the fission waste can be stored and handeld

Name one successful long term storage project. Synrock showed enormous promise, the the funding was cut before the project was finished. Dumping the stuff in the ocean in stainless steel drums, or stacking the stuff in tunnels is the current answer.

Anyway, this is a discussion on solar cells, which lend themselves to distributed power generation of some form or another - they don't have to be big. More efficiency there makes the solar powered laptop easier to acheive.

We did the time warp again?

[dbIII]

Until then, solar power will be a technical curiosity for use in special situations (outer space)

Ever seen a pocket calculator? They don't plug into the wall anymore - they started to run on batteries, and now run on solar power. Marine navigation lights don't burn parafin, they have little solar panels on top of them. A lot of microwave relay towers are solar powered. Yachts have solar panels. I would have said the exact same things in the 1990s and it is now 2004. A better solar cell helps in those applications where they are already in use, and makes other applications easier to implement.

In plain english, there are other design criteria other than a very simple equation even an economist could understand. Economies of scale mean that in most cases it is cheaper for a business to get power from a grid, no matter what powers it.

Other development

[codeButcher]

Research done here in South Africa by Prof. Vivian Alberts et al has turned up some more promising results. From another article (here, unfortunaltely not in English) some of the highlights:

• Cu, In, Ga, Se and S are deposited via a vacuum & diffusion process
• Can be deposited on plain glass (same stuff used for window panes)
• 1 micron of this stuff absorbs more sunlight than 350 microns of Si (about 99% of light - don't know how this translates to efficiency, though - article not too technical).
• Panels like these would cost roughly a tenth of the price of those currently available.
• Pilot plant for manufacturing was expected to begin manufacturing somewhere in April (this month), manufacturing panels 400mm x 500mm @ 20W
• Pilot plant (100 sq m) to cost about US$ 2.3 - probably within reach for many developing countries.

Unfortunalty there's not much more detail or Web references....