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Comment by qwertox | Hacker News Reader

Found on the internet: The average efficiency of domestic solar panels is between 18% and 24%. So let's assume 20%.

20% more powerful then means a 24% efficiency.

According to Wikipedia: As of 2024, the world record for solar cell efficiency is 47.6%, set in May 2022 by Fraunhofer ISE, with a III-V four-junction concentrating photovoltaic (CPV) cell.

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The linked press release already cites an overall efficiency of 24%. Did you purposely scour the internet just to avoid reading it?

Yes. Old cells are 20%, new cells are 24%.

To me, this means that the new cells are 4% more efficient.

To their marketing team it means that they are 20% more powerful.

Edit: Got it, the marketing team is accurate.

I'm afraid you are wrong, what you are referring to are percentage points [1].

[1] https://en.wikipedia.org/wiki/Percentage_point

Perfect. Thanks!

They are certainly both 20% more efficient and 20% more powerful. Let's say that a certain size panel gets 100W of insolation. If you move from 20W to 24W then you are generating 20% more power from the same amount of insolation, so you are 20% more efficient.

People seem to treat percentages differently from other numbers, when all it means is "divide by 100." Nobody complains when you say going from 9% to 18% is "doubling in efficiency" but if you say it is "100% more efficient" or "200% as efficient" then people complain.

If you were going to buy these, you'd find you need 20% fewer panels (of the same area) to generate the same amount of power.

Sounds like the marketing team is right about this one.

Your 4% are not percent, but percentage points. The marketing team is right about this one.

4 / 20 = 0.2 aka 20 percent.

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