October 2, 2006 4:00 AM PDT

Silicon vs. CIGS: With solar energy, the issue is material

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Most other solar makers sit at 15 percent to 18 percent efficiency. Still, a physical limit is a physical limit and silicon makers acknowledge they are approaching a barrier. Additional layers made of different materials could be added to silicon panels to harvest more energy, but that adds to the cost.

Progress in the industry instead revolves around reducing the cost of the panels. So far, it's working. SunPower, among others, has figured out ways to automate many factory procedures. It also builds factories in the Philippines, where labor remains cheap. Panels are also getting thinner, which reduces the material needed and increases efficiency.

"Silicon has a reliability record which is unmatched by any other material."
--T.J. Rodgers, CEO of Cypress Semiconductor

Right now, it takes about nine to 10 years for the cost of a solar installation to pay for itself--meaning the cost equals the amount you would have paid the power company in electric bills. In five years, silicon makers claim they can cut that time in half.

And as an added bonus, solar panels aren't as ugly as they used to be. PowerLight has come out with roof tiles with embedded silicon solar panels, which get installed when a house is built. A complete system can run around $8,000 to $13,000, according to Grupe Homes, which has included PowerLight panels in some homes in a few relatively new developments.

Solar needs real estate

The problem, however, is that solar electricity takes a lot of real estate, said Stanberry. The sun radiates about a kilowatt of energy per square meter on the surface of earth. There are 2.6 million square meters in a square mile. Thus, every square mile gets about 2.6 gigawatts. (A million kilowatts equals a gigawatt.)

On a practical level, solar energy is only going to harvest about 10 percent of the energy that hits a large area, so it takes about 4 square miles of solar panels to generate a gigawatt, or about the same amount of electricity provided by two power plants.

"If you look at the thousands of things that humans do, there are only three things that take up thousands of square miles: agriculture, highways and construction," said Stanberry. "The unavoidable goal of solar technology is how do you cover thousands of square miles inexpensively."

CIGS, say advocates, can do this because the panels are cheap to make. David Pearce, CEO of CIGS manufacturer Miasole, says that his company can erect a factory that can put out 100 megawatts worth of solar panels a year for $25 million. (The measurement means that, if you gathered all of the panels produced by the factory, they could provide 100 megawatts of power at the same time.)

Evergreen Solar, a silicon maker, plunked down $75 million to build a 30-megawatt facility in Germany in 2006. While extra capacity can be added more cheaply than the first 30 megawatts, CIGS still has a cost advantage, says Pearce.

"The battle is going to be won on the manufacturing floor. What we have to do is transfer this into high-volume production," he said at a recent conference.

In 2010, the costs of generating a watt of electricity from a CIGS panel--including installation and other expenses--will come to around $2.50, when you consider the lifetime of the panel. That will be roughly equal to grid power at the time, Pearce said.

By the end of next year, Miasole expects to have the installed capacity to produce 200 megawatts-worth of panels a year. Pearce further added that the company will be profitable next year.

While it trails in efficiency, CIGS is not far away, Miasole has shown a CIGS solar cell that converts 19.5 percent of sunlight into electricity; in a manufacturing environment, that means 15 percent to 16 percent efficiency, the company acknowledges.

So why isn't CIGS a perfect solution? It barely exists commercially and the alternatives don't have a great track record. Thirty years ago, producing solar energy cost about $100 a watt, said Swanson, so the U.S. Department of Energy began to fund alternatives to silicon. Now, it's about $8 or $9 and going down. The alternatives are just getting out of the research phase. Reliability of silicon, he added, is unquestioned.

The fact that CIGS can go on a variety of surfaces also may not be as big an advantage as it looks.

"There is a lot of roof space on American homes," said Ron Kenedi, general manager of the solar unit at Sharp, one of the big silicon solar makers.

Ultimately, the two technologies could co-exist by going into different applications, said Walter Nasdeo, an analyst at Ardour Capital.

"It's a hard question to answer. If you are talking about solar on a house, you're probably better off using silicon, particularly in the near term. It's been around for a long time," he said. By contrast, CIGS might be best suited for large industrial roofs or signs. Then over time, CIGS could build out a network of home installers.

"Right now what they (CIGS makers) face are engineering issues, not technical issues," he said.

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22 comments

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Solar panels/CIGS on rooftops sounds ideal
You'll get that double whammy:

- create electricity to power the air conditioning,
- less heat from the sun hitting the surface means less heat to aircondition away inside

Plus the fact that your
Posted by jpsalvesen (31 comments )
Reply Link Flag
Solar panels/CIGS on rooftops sounds ideal
You'll get that double whammy:

- create electricity to power the air conditioning,
- less heat from the sun hitting the surface means less heat to aircondition away inside

Do they take this into account when they calculate the estimated ROI?
Posted by jpsalvesen (31 comments )
Reply Link Flag
No electricity Needed fo Solar Cooling
the peak demand for electricity is created by air conditioning loads.

Remember the referigerator in your camper that ran on propaine? There are several absorption chillers that use hot water or engine exhaust as the energy input.

The most common application today is in cogeneration, the waste heat from gas turbine or diesel generators is used to air condition buildings.

Solar heated water can also be used. Of ocurse electricity is still needed to run fans and pumps, but using solar heat directly for cooling and heating bypasses the inefficiencies of converting to electricity and then converting to mechanical motion in an electric motor, and finally to cooling.

One advantage of solar input for air conditioning, the available solar energy tracks air conditioning demand.
Posted by disco-legend-zeke (448 comments )
Reply Link Flag
Sounds like Sterling
That sounds like a Sterling engine app. That kind of stuff makes a lot of sense. If you combine a lot of these different techs and get away from things like Incandesent bulbs that are wasteful, we could do away with much of the fossil fuel issue.
Posted by MrHandle (71 comments )
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Sounds like Sterling
Sounds like Sterling Engine apps, where you can use waste heat for cooling amoung other things. It's good to see that sort of efficiency. By using the energy from sunlight (especially in a solar-concentration/Sterling design) to offset heat waste, engines can be highly efficient.
Posted by MrHandle (71 comments )
Link Flag
re: air conditioning, try white roofs, GSHP, and swamp coolers b4 u funk it up w/ anything hi-tech.
Posted by maxwellsagain (2 comments )
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False hopes for CIGS
Misguided hopes, investments and government funding appropriated to CIGS and other thin films is probably the main reason the US market share of PV module manufacturing has monotonically and precipitously fallen from a leadership position of 45% in 1995 to about 9% in 2005. The smart money is not in the US, but in Japan, Germany, and other countries that have realized silicon is "where its at" for PV.

So CIGS is 100 time thinner. So what? Our Planet's crust contains 27% silicon (outdone only by oxygen at 46%) What could be more plentiful and widely available than sand -- Si02? There is 0.007% copper, 0.00001% indium, 0.0015% gallium, and 0.000009% selenium in the crust. And these elements are not particularly easy to mine in quantities required for gigawatts of solar cells. Do the math. Just the recent upsurge in flat panel display applications threw the indium markets is a tizzy.

Silicon photovoltaic feedstock material manufacturing is merely at a mismatch in planned capacity vs actual demand. This situation will correct itself within two years and leave CIGS in the (SiO2) dust with a nano-sized market share of world PV sales.
Posted by Siliconsultant (1 comment )
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Silicon Shortage
lol. Yeah, I keep seeing about this "shortage" of Silicon, when it's the second most abundant material on Earth. I guess it requires very high heats to work with, but we'll never run out of the stuff. My guess is that they'll continue to find ways to refine the manufacture of it and improve efficiency a bit. I also think it will continue to dominate. CIGS may have a few niche apps, but that's about it in my view..
Posted by MrHandle (71 comments )
Link Flag
Silicon under pressure...?!
One thing is clear based on the rather unusual statement from T.J. Rogers: The silicon-wafer solar guys appear rather scared and on the edge...otherwise the CEO of a publicly traded company like Rogers wouldn't be losing it like this in public...! I guess with more than a dozen CIGS startups after you and investors increasingly wondering whether silicon cell production is not a cashflow black hole, the open nerves are understandable...
Posted by steph111 (1 comment )
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Solar power is a joke
Solar power is a joke. There's very little energy in a square foot of sunlight. It's never going to matter. It's just an impractical dream of environmentalists who don't want wind power in their own backyards.
Posted by lingsun (482 comments )
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a 100 sq meter house = 100 KW insolation -- even at 10% is 10KW
and for air conditioning, efficiencies could be much better.

no, solar is real. actually, petrolium is simply stored solar, after all.
Posted by disco-legend-zeke (448 comments )
Link Flag
Solar/Wind Power Hallucination
Both solar and wind power are a joke. Enter the friendly atom.

Either the Toshiba 4S or Mitsubishi APWR reactors provide more power per square foot than solar or wind power ever will.
Posted by Too Old For IT (351 comments )
Link Flag
Is it?
My solar powered calculators work just fine (during the day of course lol). And, they have more processing power than Eniac (the huge power-sucking first digital computer) did. The point is that we still use stuff like Incandescent bulbs that are extremely wasteful. If we would use energy much more efficiently, we wouldn't need so much of it. Solar alone isn't enough, but if we combine it with other things like wind, Sterling Engine, and intellingent energy management, we could be alright.

Personally, I'd like to see more effort put into developing fussion, but until that time, it doesn't hurt to try and get all we can from all possible sources.
Posted by MrHandle (71 comments )
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Solar power no joke.
30 years ago the internet was a joke too. Currently solar has a 9 to 10 year payback period, not worth it at credit card rates if you are on the grid.

But wait, solar is expanding rapidly. Why? As it gets cheaper per watt more and more uses become economical. Those solar walk lights are everywhere, as solar calculators have been for years. Now warning signs and street signs are being lit with solar. Campers are buying solar panels that roll up. Hopefully, port-a-potties will get solar fans soon.

Got a cabin in the middle of nowhere? Why pay hundreds per pole to bring the grid to you? Just buy some panels, batteries, ... for less. Want to wi-fi a city? Just put a small solar panel, UPS, and an access point on every street corner. No need for wires or meter readers.

If solar ever gets cheap enough and durable enough (a big if), how much energy would be created if all roads were covered with spray-on solar panels?
Posted by galeso (283 comments )
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Wrong
If you cover about 10% of the state of Navada with solar panels. You would have enough energy to power the entire country. That is becouse enough energy from the sun hits the earth every hour that it takes us a year to match. Don't beleve me? Watch the Renewable Energy episode of Modern Marvels on the History Channel.
Posted by DJRWolf (6 comments )
Link Flag
lingsun, you're name has no power either.
No offense, lingsun, but that's about the most scientifically uneducated BS I've read in a long time, thanks for the laugh though! :)
Posted by foremanjf (2 comments )
Link Flag
Sans atmos, downward direct solar irrad is about 1.3kw/m2. W/ an atmos, max is roughly 900 watts on a clear day. Given clouds, fog, diurnal/seasonal sun arc, sub-optimal angle of inclination/placement, etc., typical temperate zone irradiance might be in the neighborhood of 300-400 watts/m2 for 8 hours/day or 2,4-3.2kwh/day/m2, but more in the U.S. sw sun belt. Figure typical home roof area of 100m2 and maybe 1/3 of that well-positioned for photovoltaic reception. Ergo, in the sun belt 1/3 of your roof might receive a solar irradiance of 100kwh/day. So, if you could powder it w/ 35% efficient photovoltaics, you'd have 35kwh/day, which is 1050kwh/month, more than the standard home needs. With a few items like switch to fluorescent bulbs, energy-star appliances and remote shut-off power strip switches for solid state home electronics to stop dark current, average U.S. home electrical use could fall below 500kwh/month, except for air conditioning. Minimizing the latter need with white elastomeric roof paint and a ground source heat pump, you'd then have enough spare juice to charge your back-up power/load leveler aka your plug-in hybrid electric vehicle.

So, conceivably, w/i 5-10 years you could pretty much go off-grid. What that would cost is right now anybody's guess, but if it drops below a loanable $20k net initial entry above standard setup, it'll get VERY tempting. Let's see...rebuild my deck w/a fancy barbecue or go off-grid? Hmmm....
Posted by maxwellsagain (2 comments )
Link Flag
CPV, smaller expense
Perhaps fossil fuels will be cheaper and so abundant in the future that solar will never compete? However, in the mean time, CPV could make up the difference since only a small amount of expense is shared with such things as mass produced mirrors, sensors and motors.
Posted by fireofenergy (18 comments )
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Solar could be our saviour
Whichever one wins the Battle, solar is by far the best solution to all our energy problems. Nuclear is too dangerous (think terrorism) and fossil fuels will pollute us to extinction. The only good answer is solar. We just need to work together to automate the manufacturing processes so much that we can roll them out and install them by the terawatt. Cost will definitely beat out fossil fuels very soon with economies of scale. Let's all jump on the band wagon here. There is more than enough room for all of us here.
Posted by lmacmich (2 comments )
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Electroplating of solar cell conductors
Regardless of which method is used - Si or CIGS - electroplating of solar cell conductors will be used to boos solar cell efficiencies. -Rob Schetty
Posted by persimmons2 (1 comment )
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How does Dyesol's DSC technology rate against thin film and conventional silicon based solar? The market cap of Dyesol is still extremely low relative to alternative players across the field.
Posted by Impala1948 (1 comment )
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