[YoungWeb]

"kWh Analytics’ most recent figures place the median annual degradation for residential solar systems as 1.09% and non-residential systems at 0.8%. The report states that over a 20-year asset life, project degradation could therefore be underestimated by as much as 14%, resulting in severaly overestimated performance and revenue forecasts produced within a P50 model."

[toomuchtodo]

A solar panel’s performance warranty will typically guarantee 90% production at 10 years and 80% at 25 years. It looks like some panels are going to come up a bit short, but at current solar PV module improvement and manufacturing rates, it’s not a show stopper to have current panels exhibit a bit less longevity than anticipated. Very similar to LEDs with longevity promises that aren’t entirely being kept but are still good enough.

Panels have gotten so much better, I know folks who replaced 10-15 year old panels with brand new panels, even though they were still producing and within warranty. Panels are also entirely recyclable and infra to do so is being spun up.

[kragen]

Indeed! However, generation companies bidding on PPAs are in a somewhat different situation from LED lighting customers; if they bid 2% higher than the competition, they lose the deal, and if they bid 2% lower than what they'll actually produce, they build the plant and lose money on the deal. So if the average panel efficiency over a 20-year PPA is 91.0% of the initial efficiency (as this article suggests), but they'd budgeted for 95.4%, that's potentially a huge deal for them; it's the difference between being 2.3% low and 2.3% high.

By contrast, there are very few businesses that will be unprofitable if their LED lightbulbs burn out 2.3% faster than predicted. (LED lightbulbs burning out is a stupid market-for-lemons market failure, but that's a different topic.)

Panels getting better is actually another potential risk for these projects—if, three years from now, low-cost PV modules cost €0.09 per peak watt instead of €0.17 like today, then PV plants built at that point will have dramatically lower costs than PV plants built today, and probably PPAs signed then will also have dramatically lower costs. When plants are built without a PPA, this could result in those plants being "stranded assets" that can't make enough money to pay the interest on the bank loan, like many coal plants today, but even when there is a PPA, the electric utilities and ratepayers (who in many cases are also taxpayers) have strong incentives to find ways to circumvent it, for example through inflation or bankruptcy.

Now, €0.09/Wp sounds like a ridiculously low price; window glass, for example, costs substantially more than that. It's hard to see how PV panels could reduce their raw material use enough to get that low. So maybe it won't happen. Or maybe we'll find a way. (In Derctuo, for example, I suggested that new solar modules could use chicken wire instead of glass, though that might drop the efficiency of low-cost panels from 16% to 15%.)

[toomuchtodo]

I don’t think they’ll be stranded assets as a gas plant would be, as there’s no marginal cost for fuel. If the project doesn’t break even, debt will be shed, someone will take a haircut, and the solar asset will continue to produce. We’re only talking a handful of basis points here.

[kragen]

That's a good point. The bank might prefer a haircut to litigating an insolvency, especially if the best-case scenario for the insolvency is that they get possession of the power plant.

[cure]

Indeed - the LG NEON-R 365 panels I got two years ago have these specs:

* First 5 years : 95% * After 5th year : 0.4% annual degradation * 25 years : 88.4%

The NEON-2 380W from this year looks roughly equivalent, and they have these specs:

* 1st year 98.5% * from 2-24th year: 0.33%/year down * 90.6% at year 25

[ArkanExplorer]

Do we have any insight on what these panels will be like 30, 50, 80 years in the future?

This is the lifespan of some homes, and power plants.

[lkbm]

The standard lifespan for a roof seems to be ~20 years, though that seems low to me.

[toomuchtodo]

That’s a reasonable estimate based on architectural shingles, although 15 years is more likely in latitudes with more solar exposure throughout the year (the Sunbelt in the US). Metal roofs last longer, but have a higher initial upfront cost. Huge fan of metal standing seam roofs for longevity (40-70 year lifetime) as well as robust mount support (clipping to the seams) for solar racking.

https://youtu.be/k6mrRUZv8Ak

[nicoburns]

This thread has loads of people talking about roofs lasting 50-100 years https://forums.moneysavingexpert.com/discussion/5575330/when...

[quickthrowman]

Yes, there are types of roofs that last a long time. Standing seam metal, slate, clay, concrete, and copper roofs all last a long time (50+ years). Asphalt shingles and EPDM flat roofs last 15-25, cedar shakes can last 30+ years.

The long lasting ones are substantially more expensive than asphalt shingles, 3x at a minimum.

[toomuchtodo]

My estimate is what home insurers use. Roofs can and do last longer.

[PaulDavisThe1st]

That's a US roof covered in asphalt shingles.

Stone, slate, tile roofs in Europe (and in some parts of the US) have lifespans measured in centuries.

[rsj_hn]

We just had to replace our tile roof for a 20 year old house. I've seen estimates of 20-50 years and I'm sure you can find some that last centuries, just don't buy a tile roof expecting it to do that. There are still Ford model T's on the road today, but we don't tell people that cars last a century.

[PaulDavisThe1st]

I had a house in Phila. with a tile roof, built in 1920. I "replaced" the roof in 1995, and by that I literally mean re-placed: the roofers carefully took all the tile off the roof, put down two layers of 80lb roofing felt, and reinstalled all the tile. They believed that the original was done with only 1 layer of 40lb roofing felt, and that this was the only thing that had actually failed other than a couple of cracked tiles. There was some expectation that the new one might last 100 years before it would need the same process again.

[laurencerowe]

What was the failure mode of your tile roof that meant it needed replacing? Coming from the UK where most roofs are tile I don’t think I ever saw one need replacing there, maybe a few tiles need realigning. Most tile roofs were the same as the house itself, so over a century for large swaths of the country. The weather is less extreme than in the US though.

[abfan1127]

how are panels entirely recyclable?

[toomuchtodo]

They are run through a shredder and the materials reclaimed. Veolia in Europe has a plant in production, Australia is building one.

[imtringued]

Entirely may be hyperbole but solar panels are mostly glass and aluminum by weight and wafers can be resurfaced.