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Comment by QAPereo | Hacker News Reader

Does anyone have any information on how efficient these are how long they last and that kind of thing? All I got for the article was a lot of hype and $10 a meter.

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> "In terms of efficiency, the solar cells are currently showing around a 2-2.5 per cent power conversion rate" [1]

Since you can probably get 250-350 watts of sunlight (avg) per square meter, it means 1 sq m generates 5 to 8.75 watts. Which is 0.5 to 0.875 watts per dollar (or $1.14-$2 per watt).

I don't think that's cheaper than the current offerings, especially if you don't consider these printed panels take 10X more space. Also the lifespan isn't known.

But consider that the price of these new panels will likely fall, if mass-produced.

[1]: https://cleantechnica.com/2017/05/17/researchers-australias-...

EDIT:

Other people say it's $0.40 per watt. [2]

[2]: http://www.thefifthestate.com.au/energy-lead/energy/cheap-an...

I'm not sure where you are getting the 250-300W/m2 of irradiance. The standard value used in all solar industry calulations is 1000W/m2, but in practice, you should expect to see 800W/m2 at sea level and moderate lattitude.

Average capacity factor for solar cell is about 25% (night, clouds, seasons, etc).

1000W/m2 * 0.25 => ~250W/m2.

1000W/m^2 is average daily peak irradiance. That number is useful for designing system capacity, but doesn't reflect output throughout the day.

1000W/m2 is at noon at the equator without clouds/haze/dust.

1000W m^2 is actualy closer to high noon at Kansas on a fully clear day (this is equivalent to 2,000 umol/cm^2/s-1) Equatorial solar irradiance is actually higher (closer to 1,050W/m^2) because the equator is just a bit closer to the sun.

>Equatorial solar irradiance is actually higher (closer to 1,050W/m^2) because the equator is just a bit closer to the sun.

No, no, no. Equatorial is higher because the sun is more directly overhead on average than in Kansas.

That's not how the inverse square law works for photon flux density.

Maybe that's the 24-hour average?

Woild like to know normal panel's efficiancy and costs for comparison

You can buy solar cells off aliexpress at ~$0.33 / watt (this is the lowest price atm). The most efficient cells are at 23-25% efficiency, but these are a bit more expensive (closer to $0.5).

Here's the first example I could find (https://www.aliexpress.com/item/10-Pcs-17-6-125-x-125MM-Mono...).

In the real world you cannot expect to need less than around 5 square meters for 1kW of peak power (using the most efficient panels), the standard "rule of the thumb" being 7 sq meters per 1 kW, some lower efficiency panels (not used anymore) will stretch that up to nearly 9 square meters per 1kW.

This puts the efficiency in a range between 1/9 and 1/5, i.e. between 11 and 20%.

So if this new panel has a 1/10-1/8 of the best above, it plainly means that you will need in your typical single home installation more space than your roof has.

Let's take a 6 kW installation, with best current panels it will be 30 square meters or however at the most 45, with these printed thingies more like 240-300 sqm or more.

And 2-3 years of expected life!

Maybe the principle is fine but it must be modified/bettered to raise the efficiency and to increase the durability.

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