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Cheap Plastic Solar

plasticsolardenmark.jpgResearchers at the Danish group Risø have developed a polymer photovoltaic technology that would cost about 2% of current silicon PV panels: Risø claims that their new polymer pv should run about $15/square meter, as opposed to the $800/square meter they list for silicon. Moreover, this plastic solar cell has a useful lifespan of about two and a half years, which Risø claims to be a record duration for plastic pv.

So what's the downside? Efficiency. These cells have a conversion factor of 0.2% to 5%, as compared to common silicon pv at 12%-15%; photovoltaics in development have achieved up to 50% or so in the lab.

What can you do with 0.2%-5% efficiency? At first blush, not much, which is with Risø is now devoting its efforts to increasing the power output of their plastic solar.

But the tremendous price reduction changes the equation a bit. At $15/square meter, it becomes much more economically feasible to add a solar boost to otherwise unused external spaces. 50 watts for $15 (assuming the high end of the efficiency scale) isn't too bad; I could imagine homeowners wanting to put this material on south-facing walls, rooftops, even patio umbrellas. (As I think about it, it seems to me that this material as part of a beach umbrella would be great -- the power production from the typical 2m-diameter umbrella would be about 150-170 watts, enough to keep a phone or radio charged.) You're not going to power your entire house with this stuff, at least not at this level of efficiency, but even low-efficiency solar can be helpful.

Get it to 10% or 20% and keep the same price and durability, though, and you have the makings of a revolution.

(Via Sustainability Zone)


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Comments (14)

Craig Smith:

I think it’s worth pointing out, as Jamais has done before, that the real issue isn’t the efficiency or initial cost, but the installed cost per watt. Part of the downside with these is efficiency, but also the relatively short life span. Current silicon PV panels come with a 25 warrantee, meaning you’d have to replace these polymer ones ten times to get a comparable lifespan. However a system that is only 5% efficient in turning sunlight into electricity, but can do it at $0.05/kwh over the life of the product is a guaranteed winner. Once we get a photovoltaic system that is cost competitive with existing non-renewable energy sources sustainability becomes a downhill battle (I hope).

This isn't at that level yet, but it's not too far off. Assuming 50 watts power for an pessimistic average of 2 usable hours/day x 200 usable days/year, for 2.5 years and $15, the result is (by my calculations) thirty cents/kilowatt-hour. A place with better sunlight patterns would be close to competitive (e.g., 5 usable hours x 300 days/year, otherwise the same, equals 8 cents/kwh).

This seems like a change of topic, but perhaps not. It's interesting to think about the cost per kilowatt-hour and the longevity of *batteries*. If this could power a laptop, digital camera, iPod or cell phone, it would be very competitive.

I came up with the idea of solar awnings; you use them to keep unwanted heat out of your windows, and they convert some of it to juice to run your air conditioner.

The cost is the interesting part.  Assuming a mid-Kansas insolation of 1550 kWh/m^2/year, a 5% efficient panel would yield 77.5 kWh out per year.  Assuming 30 months of operation at 5% (how fast does performance degrade?) for $15, you'd get 7.74¢/kWh.  This is extremely competitive.

It's even better when you consider that the short life is an advantage in this situation; if the cost of electricity falls due to even more efficient versions flooding the grid with solar watts, you are not locked into a long-term investment.  After 30 months you replace the degraded material with new and start over.

Could you power your house?  Time to haul out the virtual envelope....

If your house is 40 feet E-W (call it 11 meters) and you put up a 2-meter wide awning along the full width to shade all the windows from summer sun, you'd have 22 square meters of awning.  At 1000 W/m^2 insolation and 5% conversion, you'd have 1100 watts; about enough to run a window A/C, and close to the average consumption of the house.  If you unrolled another 2 meter width along the south-facing part of the roof and it was perpendicular to the summer sun, you'd get another 1100 peak watts.

Yes, you could power your house with this stuff.  You'd be replacing it regularly, but it would do the job.

Excellent to have some numbers on this, E-P -- thanks!

The other advantage to its relatively short lifecycle is that you aren't locked into an obsolete version for too long. By the time a couple of years have passed, the replacement version should be even better.


Even though I must confess that I know little of solar panels and such, I still find this very fasinating. Even though powering a house with these seems plausible, IMHO it seems as though a very cheap "gadget-juicer" would easily become popular. (Charging Cell Phones, iPods and perhaps even laptops.) And at a price that would most likely be largely cheaper than current, similar, solutions. :)

So when can we start to buying a few meters sunpower for that patio wall?

I like E-P's idea very much. This would be especially useful on low-rise commercial buildings, which have high internal heat gains and need efficient shading. I say "low-rise" because wind and maintenance issues would make this an expensive option for high-rise buildings.

Costs need to include inverter and grid inter-tie, or inverter and batteries: the output of the PV arrays can't be directly fed to equipment like air conditioners.

It'd be great if the PV sheets were recyclable at the end of their brief lives.

Look at the cost of a 400 W computer power supply and consider that a 400 W grid-tie inverter would probably not cost very much more in the quantities that these panels would demand.

It's not quite true that PV output can't be fed directly to equipment like A/C's.  There is at least one freezer unit which has a variable-speed compressor designed to operate directly off a PV panel (IIRC, it uses phase-change materials to stay cold overnight).  If demand charges for electricity got high enough, it would be worth doing the same kind of thing for air conditioning.

Sami Grover:

The UK Environment Agencies new building is actually using a solar awning of sorts to keep the building cool in sunny weather and generate electricity simultaneously. It's using standard PV units, rather than plastic or other type of flexible, lightweight materials as discussed above, but I guess the principal is the same. Great minds...

More info here:

Any way we can get this company to talk to Konarka and maybe they could trade patents creative commons style and start The Revolution...please?

I have to wonder if this isn't at or near the point of signaling a change in the general use and perception of solar power. There have been some interesting materials developments over the past few years and there's no reason to believe this option will not become more compelling in the very near future. The mere fact that people are now to the point of discussing the possibility at the levels shown in the above comments, suggests that we may be at a significant tipping point. I certainly hope so.

Perception?  The perception has been that solar was far more expensive than conventional sources, and rightly so.  For many years the market for solar PV has been in off-grid applications from repeaters on mountains to space probes.

People are ready to switch to solar whenever it becomes cheaper.  It looks to me like this stuff would do it in huge swaths across the world; at $15 for a 50-watt area, you could power a 5000 BTU/hr air conditioner with an EER of 12 for about $135.  Forget California; you'd have all of Baghdad beating your doors down.


So if this has a 2 year life span, then are the landfills going to be inundated with this plastic? Is it biodegradable? How long is this stuff going to sit in the ground and how many extra dumps are we going to need if a significant portion of society adopts this? Or can it be melted down and reformed into new panels?

Those are excellent questions, Perigrini, and worth pursuing. Ideally, the material should be recyclable into new panels. I expect that we'll learn more as this moves from the lab to prototype development.


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