this post was submitted on 26 Jan 2026
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Solar panels are usually sold with 25 to 30 years of performance promises. But what happens after that, when the warranty language is long gone and you are

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[–] BodyBySisyphus@hexbear.net 17 points 16 hours ago* (last edited 16 hours ago) (2 children)

If you look at the study, this is based on an n of 6 and there was significant variation across altitude, so reporting this as an average or a definitive result seems a little weird.

Moreover, the degradation rate was highest in the low-altitude installations, which experienced up to 1.5% efficiency loss per year. Whether your system operating at 80% efficiency after 20 years is material to you depends on the original installation size and power consumption (obviously), but I imagine it would be a replacement signal for most.

On top of all that, given changes in solar panel tech over the years, it's not like current installations really resemble the ones in the study. Apparently thin-film solar panels have a shorter service life, but modern monocrystalline panels can be rated up to 40 years with estimated 0.3-0.5% efficiency loss per year.

It's a fun study but I'm not sure why science reporting keeps insisting on trying to generalize or why this information would be considered groundbreaking given that it seems in line with manufacturers' current understanding of how their products perform.

[–] chgxvjh@hexbear.net 8 points 13 hours ago (1 children)

If you replace panels, the old panels don't go away. Reuse at lower efficiency seems more viable than recycling.

[–] BodyBySisyphus@hexbear.net 9 points 13 hours ago (2 children)

Yeah, but if you're a residential solar customer with limited roof space and/or a weight limit, the old panels become a bit of a liability.

[–] chgxvjh@hexbear.net 8 points 13 hours ago (1 children)

Realistically a lot of it is going to end up in Africa on way or another.

I've also seen listings for used solar panels one Chinese wholesale marketplaces for 1/3 - 1/2 of the new price.

[–] Le_Wokisme@hexbear.net 8 points 11 hours ago

80% efficacy for 50% of the price sounds like it's a great deal if the tradeoffs don't matter.

[–] 7bicycles@hexbear.net 5 points 13 hours ago (1 children)

Could just use them for fence or sunshade on your property somewhere where they're not getting optimal sun. I mean if the other option is to throw them away might aswell.

[–] Le_Wokisme@hexbear.net 7 points 11 hours ago* (last edited 11 hours ago)

a degraded panel in a suboptimal position is probably not worth the effort to install and the resources that would go into supporting it.

a better re-use case would be one where the downsides aren't exacerbated but a new build panel isn't justified. also solar panels are supposedly highly recyclable.

[–] plinky@hexbear.net 7 points 16 hours ago* (last edited 16 hours ago) (1 children)

I think it would be expansion signal for most, non? adding 20% more capacity is still cheaper than rehauling the whole thingy, nor is it likely their efficiency will increase that much to save space or whatever reason

[–] BodyBySisyphus@hexbear.net 5 points 15 hours ago (1 children)

Depends on how much roof space you have left and how easy it would be to add panels to the array, I'd imagine.

[–] plinky@hexbear.net 2 points 10 hours ago (1 children)

Do most people go for the full grid independence tho? I think supplemental panels make just as much sense, and utilities forbid disconnecting anyway, so it’s more like if it works it works type dealio

[–] BodyBySisyphus@hexbear.net 1 points 7 hours ago (1 children)

According to Google you need about 300-500 sq ft of panels to power a single family home so it might be simple to start with a 100 sq ft array and gradually build it out to compensate for losses over time and spread the cost. But I'm not a rooftop solar installer shrug-outta-hecks

[–] rentasintorn@lemmygrad.ml 2 points 7 hours ago

My impression is that these have to be permitted before they're allowed to be operational (at least in the U$, depending on location or whatever). I'd guess you'd at least have to get a new inspection when more were added on?

Most solar installers around me seem to be concentrating on grifting financing/leases, so I'd think they would make this hard to do.

It does genuinely seem like a good idea, though!