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Comment by go37pi | Hacker News Reader

This solar cell has a "conversion efficiency of 9.6 percent, which is 40 percent higher than previous attempts to create a solar cell made of similar materials."

Current solar cells have approximately 20 percent efficiency. Unless this solar cell is extremely cheap, I think this is a long way from practicality.

http://upload.wikimedia.org/wikipedia/commons/a/a4/PVeff%28r... - graph of best research cell efficiencies

EDIT: "The researchers estimate that if the technology can be taken beyond its basic state right now and achieve 12 percent efficiency, it could be an economically viable alternative to current products." - from CNET news http://news.cnet.com/8301-11128_3-10451641-54.html

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Is efficiency really the #1 criterion for practicality? I thought cost (per watt) was.

That's a good point, I was implicitly assuming that the lost power due to efficiency losses would be greater than the gained power due to cheaper costs.

#1 enough.

My roof has finite surface area. If the efficiency is too low, even zero cost isn't competitive.

That's true even of commercial facilities. Various enviro groups are already trying to kill solar farms.

Somewhere in here, wire and other infrastructure (such as the frame) costs matter too.

It's a sliding scale for priority. More space per watt takes up more space for sun-power farms, and they often cause more heat, making the eco people go nuts, what with migrating geese turning into popcorn chicken above them (</exaggeration>).

For many individuals, who just have roof-space (for instance), space is really at a premium, and increased output means more money saved / made per time period, so it can pay for itself and more over time. Power companies could go either way, as they need a LOT of space. Doubling the area they need may not sound too good to them, as land costs money every year in taxes. If land is cheap enough though, cost per watt likely wins out.

The point isn't that it's close to being efficient as our current technology, it's that the materials are cheaper. Indium and gallium are a lot more expensive than tin and zinc.

I think there's a lot more surplus sunshine than surplus Ga or In.

Depends on where you are. Sunshine is a little harder to box up and ship to where it's needed.

Indeed. That's why they put the best solar panels on space probes and satellites, and why they use those with the best performance/price ratio for solar farms in the desert.

"Current solar cells have approximately 20 percent efficiency."

Not the vast majority of commercial ones (closer to 10-15% range, afaik - the ones that get around 20% (for non-concentrating) are in the lab or on satellites), and certainly not the cheaper thin film (GICS) kind with which this will compete.

Conversion rates aren't as important as with fuel driven electricity generators since the sun has unlimited fuel. Making hydrogen by burning gas however is much more crucial, why aren't we fueling cars and power plants directly instead?

Solar cells have different metrics, like cost/square meter

IF they can make them cheap enough, you can basically afford to put them everywhere. Also from a manufacturing standpoint, it will be easier to get financing to build a factory, as you are not dependent on commodity swings in scarcer metals affecting your ability to make a profit.

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