March 16, 2008
Thinner Silicon Photovoltaics For Lower Cost
A pair of articles from MIT's Technology Review report on prospects of lower solar photovoltaics manufacturing costs. First, Solaria is developing cheaper ways to make cheaper silicon-crystal based photovoltaic using thinner cells and lower cost fabrication techniques.
Solaria, a startup based in Fremont, CA, intends to cut the cost of solar panels by decreasing the amount of expensive material required. It has recently started shipping its first panels to select customers. This spring the company will begin production of solar panels at a factory built to produce 25 megawatts of solar panels per year.
Current high costs for the type of silicon used in photovoltaics have significantly driven up the price of conventional solar panels. Solaria's cells generate about 90% of a conventional solar panel's power, while using half as much silicon, says Kevin Gibson, Solaria's CTO.
The eventual expected cost reduction is only 10 to 30 percent.
Gibson says Solaria's first products will be economical enough to compete with panels produced by much larger companies, and that successive product generations will cost between 10 and 30 percent less than their competitors.
We need a much larger drop in photovoltaics cost. But 30% would be very substantial.
An approach using titanium oxide nanocrystals and organic dyes has the potential for much larger price reductions.
Cheap and easy-to-make dye-sensitized solar cells are still in the early stages of commercial production. Meanwhile, their inventor, Michael Gratzel, is working on more advanced versions of them. In a paper published in the online edition of Angewandte Chemie, Gratzel, a chemistry professor at the École Polytechnique Fédérale de Lausanne in Switzerland, presents a version of dye-sensitized cells that could be more robust and even cheaper to make than current versions.
Dyes made out of organic material could be very cheap.
New dyes are also being investigated. In commercial cells, the dyes are made of the precious metal ruthenium. But researchers have recently started to consider organic molecules as an alternative. "Organic dyes will become important because they can be cheaply made," Gratzel says. In the long run, they might also be more abundant than ruthenium.
Costs of new nuclear and coal power plant construction have skyrocketed. So the price point that solar has to get down to in order to compete has risen. Competitive photovoltaics probably require at least a two thirds price cut to below $1/Watt capacity. When will that happen? Your guess is as good as mine.
Nanosolar claims to be at $.50/kwh, and First Solar says they've reached $1.12/kwh. First Solar is verifiable - they're making money hand over fist: $500M in sales, 50% gross profit margins (of sales).
I've yet to see a suitable organic dye that was actually cheap to make compared to silicon. I've also yet to see one that doesn't bleach out within days.
For thirty years I've heard that solar cells will be competitive if their cost drops by some percent. For thirty years solar cell cost has dropped, sometimes dramatically. Yet solar cells remain uncompetitive. Sounds like Brazil, which has the economy of the future--and always will.
"solar cells remain uncompetitive"
Not at all. Prices are just high because of overwhelming demand - PV sales continue to double every 2 years.
Ruthenium runs about $425/t.oz. A lot cheaper than Rhodium which is now about $9250/t.oz.
A potential source of Platinum group metals is nuclear waste:
"One metric ton of spent fuel, at a burn up of 33 GWd/t (gigawatt days per metric ton) contains > 1 kg palladium (Pd), > 400 g rhodium (Rh) and > 2 kg ruthenium (Ru)."
"Potential Applications of Fission Platinoids in Industry" by Zdenek Kolarik and Edouard V. Renard in Platinum Metals Rev., 2005, 49, (2), 79-90
$1.12 per peak watt works out to roughly $0.03/kWh amortized over 25-years in California. You also have to add in the ancillary costs (frames, inverter, etc.), but I think it is save to say that thin-films are the tipping point. Prices may remain high for awhile, however, since demand is high and companies need to make a lot of money to sustain 35-40 % annual growth.
Robert, you're right - they are at the tipping point.
I'd quibble with the calculations: you have to include the cost of money, so $1.12 gives about 5.2 cents per KWH (assuming 7% interest, 30 year life). Add in Balance of System costs on new construction or industrial/commercial rooftops (thin film requires more sq meters/kw, which raises BOS a bit, especially for residential retrofits), and you're probably up to 10 cents, but that's competitive with retail average pricing (half of rates in many places, like Southern CA or Japan), and much lower than retail peak pricing.
PV panel pricing won't fall to $1.12 anytime soon, due to runaway demand, but it points where pricing will go eventually. Costs continue to fall (First Solar says their costs are falling 12% per year), and supply has to catch up with demand eventually.
Non-Si thin film can be expected to help pull down the cost of silicon, though there's room for all at the moment.
Fun times, especially if you've been following solar for 30 years, as I have.
Cost of money: Yes, for home solar that's pretty easy to calculate: The 30 year mortgage interest rate. But will the solar equipment last 30 years? In particular, will non-Si thin film last 30 years? My impression is that silicon lasts longer than other photovoltaics. No?
First Solar and falling costs: Why are their costs failing? What is their process?
In 2007 residential retail electric prices averaged 10.64 cents/kwh nationally. California was higher at 14.37 cents/kwh. So between California's greater amount of sun and higher electric prices solar becomes cost competitive here sooner.
But given that you can't buy installed PV at near $1.12 per kwh what does it actually cost at retail today fully installed?