Comment by defrost | Hacker News Reader

Comment by defrost | Hacker News Reader

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In the case of GW scale solar farms that's essentially true.

Polycrystalline panels last 20 years, sometimes longer (the sales pitch is "up to 25 years") but the 20% fall off in deliverable power after 10 years is real.

Monocrystalline last longer, they also gradually fall off and they cost more.

Now it's a game of Backblaze storage stats only with solar panels - how does an at scale solar farm balance purchase costs and maintainance costs, where's the optimal sweet spot for buying new and rotating out on a schedule | reacting to failure.

I'm not opposed to solar, I'm in Australia in one of the states with large amounts of residential solar and heavy mining industries that dwarf anything in the US currently going electric - we're costing out massive farms to run solar power to asia via HVDC cable.

The supply side of all that is sourcing the copper, the lithium, the aluminium framing, the long list of other raw material inputs, the processing to get from concentrate ores to usable elements, etc.

> Polycrystalline panels last 20 years, sometimes longer (the sales pitch is "up to 25 years") but the 20% fal

Your numbers seem off by atleast a facotor of 2. Average degradation is .5% per year so panels are guarantees are usually that you'll have 90% capacity after 10 years and 80% after 20 years.

> Now it's a game of Backblaze storage stats only with solar panels - how does an at scale solar farm balance purchase costs and maintainance costs,

The failure mode for solar is unlike traditional spinning hard drives. There isn't a "data loss" downside to waiting to replace. There won't be any risk mitigation, just calculations of when the opportunity costs become high enough to warrant replacement. I suspect in areas with cheap land, it'll be easier to build additional capacity than to replace existing degraded panels.

As I mentioned in a peer comment I'm more interested in tropical | equatorial performance and the vast majority of PV performance studies are in temperate climates - it's not currently clear whether monocrsytalline deliver peak power in such climates .. quoting a study I have here:

     His work has shown that in this tropical climate, with high ambient temperatures and high humidity during the wet season, the a-Si array produces up to 20% more energy than ...

(It's an ongoing bit of work ATM)

The optimisation issues include other factors, the cost of panel cooling techniques Vs their benefits for one.

Your average degradation figures are the figures from big meta studies such as the US Dept of Energy NREL lab Photovoltaic Degradation Rates https://www.nrel.gov/docs/fy12osti/51664.pdf which you'll notice is dominated by temperate climate studies at the latitudes of Perth | Melbourne | Germany | Arcata, California etc.

> As I mentioned in a peer comment I'm more interested in tropical | equatorial performance

Perhaps you should qualify your statements, because this:

> Currently panels drop to 80% efficacy after 10 years and are doorstops in 20

This is an unqualified factual statement and is simply not true.

> Your average degradation figures are the figures from big meta studies

The big meta studies do show that degradation is a bit faster in higher temp environments for some kinds of panels. There is however zero evidence that solar panels will be "door stops in 20".

> There is however zero evidence that solar panels will be "door stops in 20".

If you're building a large area solar farm to ship power to Singapore would you keep a panel after 20 years or door stop it?

What if the peak power output for particular climatic conditions comes from lesser used cheaper PV types that degrade faster than common ones at temperate latitudes?

The people studying this are coming at this with mindset of those that move 800 million tonne of iron ore per annum.

My original comment was framed to indicate the interest was hyper efficient at scale deployment in specific environments .. not running a beer fridge in Melbourne.

> My original comment was framed to indicate the interest was hyper efficient at scale deployment in specific environments

No, it wasn't. If that was your intent, you should go reread it to see why everyone else sees you making a clearly false claim that does not contribute to the discussion.

> If you're building a large area solar farm to ship power to Singapore would you keep a panel after 20 years or door stop it?

That's gonna depend on land value, non-panel infrastructure costs and replacement costs. If replacement costs are high then and land value and other infrastructure costs are low, then solar farms will be expanded and replacement will be delayed. If the opposite then you'll see existing panels replaced sooner.

I do expect that in a couple of decades we will see solar panel reconditioning and recycling becoming increasingly important.

> the 20% fall off in deliverable power after 10 years is real

If it's real, why don't you provide evidence?

It's a wildly exaggerated figure. Maxeon cells are rated for 0.25% degradation per year which works out to about 8% in 30 years. An inferior cell might be rated for 0.75% which works out to 20% in 30 years rather than 10 years. I believe a lot of the panels rated for 0.75% are seeing around half that actual rate of degradation.

Yup that's what I found with a cursory google, I kind of hoped OP would at least have the courage to post some reference even if it wasn't accurate, but no.

Unfortunately this is par for the course in discussions with nuclear power cultists. It honestly is that bad.

> If it's real, why don't you provide evidence?

Because I went to bed, it was late in my time zone.

> nuclear power cultists.

Say what now? Are you an idiot?

The vast bulk of PV performance studies are dominated by relatively short term studies in temperate climates - the latitudes of California and Germany eg:

https://www.nrel.gov/docs/fy12osti/51664.pdf

references Australia and links to papers from Perth and Melbourne which are cooler climates.

See my comment above re: my region of interest - equatorial tropical regions with harhser temperature cycling and probable requirements for cooling to maximise returns (still part of an open study).

I'd be happy to provide more details but I'm afraid your comment above doesn't warrent engagement.

Calling someone a cultist because they went to bed and didn't reply in a timeframe you considered proper is not suitable discussion for HN.

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