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Last year, I built DIY solar on my garden shed. I got the modules for free, they had been installed on a supermarket roof for over 20 years. The manufacturer no longer exists, but the modules are still > 95% efficient. Of course new modules are smaller and produce twice as much electricity in the same space. But I didn’t care, I had the space and I really like the solar punk look of the old blue modules. Feels good to reuse them.
I’m sure they will build them to fail
The real question is, will it be worth replacing them with whatever is out after 25 years of efficiency improvements.
Most roofing in the US barely lasts 25 years.
25 years? Good luck getting even that far, unless you put solar panels on top of them…
(Replaced roof after 15 years, and lots of repairs starting at 10 years)
25 years is still a very long time.
accounting depreciation is different from real world performance
Depreciation says a computer evaporates after 3 or 5 years in most companies.
These days computers are replaced after the 3-year service warranty in many companies, we would just toss them to the recyclers (or the back of my car sometimes if I had a project happening at home…) Occasionally they would find second use somewhere reliability didn’t matter, but a lot of IT managers won’t risk it, production downtime for a $700 PC is not worth it. My last job in a factory I had to get written permission from an IT manager to redeploy an out-of-warranty system, or could be fired when it failed.
I see. that’s good for us, since lightly pre-owned corpo laptops are cheap
With planned obselecence they might as well
“warranty” is a label that manufacturers put on the product for legal reasons. there’s no reason to assume that the product will break after that point. literally some products last 5x what’s written on the warranty.
In most industries for expensive items, manufacturers devise warranties to run out before the product is broken. Making it longer has a relatively small benefit (consumers might put a little bit more confidence in the longevity of a product with a 25 year warranty than one with a 20 year warranty), and making it too long has a pretty high cost (a bunch of warranty claims).
Especially if the useful lifetime is not well known, the incentive is for manufacturers to underpromise in their warranties. All of this applied to solar panels sold 25 years ago, and 25 years was long enough to sell people in solar panels and a line of credit as something that would pay for itself. In that context, I think it would be surprising if the panels didn’t last far longer than the warranty promised.
It’s just the time the manufacturer is willing (or forced) to be held liable for certain defects to be caused by manufacturing errors instead of expected wear and material degradation.
Unless something is mission- or safety-critical, replacing it before it breaks is wasteful.
exactly! they can last at least 2.5 decades.
At least add “more” afterwards…
They could last up to 2.5 decades or more!
How’s that?
but that would be grammatically incorrect, wouldn’t it?
Right, maybe it’s “longer” instead? Not sure!
We have some 25yo panels around, small 25-40W ones. They usually die because the diode goes (which is fixable) or one of the traces in the back gets water in it and it shorts. We’re probably down to about 2 out of 10, and those were high quality panels at the time.
And for what we paid for one 40W panel then, you could buy 2000W worth today.
The development in recent years has been insane. I’m positively astounded.
@poVoq 25 years is decades
My grandmother had an incandescent light bulb in her house that had been there since the early 1900s and still worked. But, compared to modern bulbs it was pretty dim, used very thick glass, and was pretty overbuilt. Modern incandescent bulbs are not built to last. They’re brighter, and they’re cheaper, but not as durable.
Looking at the picture, I wonder if modern panels will last the same way.
Solar panels in the 1980s were big, inefficient, chonky things. If they weren’t hand assembled, they sure looked hand-assembled.
Modern solar cells are much more efficient and clearly machine assembled. They use much finer wires, which might be more fragile:
It wouldn’t surprise me if part of the trade off to get cells that have double the efficiency at half the price you also have to give up on some durability.
Modern LED bulbs last far longer than incandescent ones
This is not news but a useful reminder nonetheless.
Advances in efficiency may cause replacing them to be viable. Still.
Possibly of relevance to this instance… my dad’s place is already in a situation where this would make senses. He did solar early, and has 235w panels. It was not quite sufficient to cover his demand, but close. Current panels of the same footprint are 400w. Replacing them would give him coverage of his needs, plus enough to charge an EV, which weren’t really a thing when he installed the solar array. His array isn’t even on a rooftop. It’s on a canopy in the yard. He designed it thinking some time down the road he’d replace the panels and inverter if need/opportunity arose.
Unfortunately our electric utility changed their net metering and permitting rules, and he can’t replace the panels and inverter. They’ll only permit it as a new system, which would mean dramatically more expense than just panels and inverter. He’d get a markedly worse rate plan, and would need to install batteries as well.
Replacing them would be a financial no-brainer, and a quick job if not for the utility.
They continue to work, even if output is degraded. Newer planels installed in the same location overheated and their elements cracked, indicating inferior manufacturing quality, but the oldest batch is not showing this symptom.
If he’s going to have to install batteries, would it make sense to shove all that permitting money into more batteries and go completely off-grid instead?
At least around here, you can just tell the utility company to fuck off if you are off-grid
I wish we could still install the old panels somewhere. They might not be good enough to be rooftop solar anymore, but in the field, why not take all they can still give?
Because solar panels are dirt cheap to produce and your time and construction materials and land has value. Recognizing trash is vital for an eco friendly economy.
Edit: some red necks do use old solar panels for off grid, low cost setups.
a grid-tie inverter could get the last bit of juice out of them
Yes. But they don’t produce power by themselves. They need light. Hence mounting, countryside etc. That’s effort.
But that relies on the capitalist assumption that producing trash and CO2 is free because you can dump it withouth having to pay for it, and destroying nature to stripmine for the raw resources only costs the purchasing price because the environment isn’t monetized.
Plus the imperialist assertion that providing decentralized electricity to poor people in developing nations is net negative because it increases the cost of labor from those regions because they can do other productive things than work in your factory.
No. It relies on the assumption that newer panels produce more energy hence are more eco friendly.
Plus: I explicitly mentioned them being a great opportunity for the poor.
Also Pakistan is rapidly building out solar panels without that.
Depends on how you define eco friendly.
The old panels already exist so if you can use them without having to transport them across the world (like the parent comment suggests), continuing to use them is eco-friendlier than producing new ones, which requires additional CO2 from manufacturing
Not doing anything at all has the lowest emissions. But it is obviously not the best way to curb impact while preserving lives and quality of life.
Your adversity to investments that do pay off would be a great hinderance to society as a whole.
Solar panels can be recycled, take very little materials and manufacturing and are usually not the limiting factor when it comes to transitioning into a low damage economy.
Throwing away great amounts of cheap solar power because you would have to lift a finger to achieve it is not… Great.
Using something that still works as long as it doesn’t produce emissions…. Is actually the single best way to curb impact, yeah.
Like literally the best use is long-term. If it still works and you can eek some power out of it rather than toss it, there’s no harm doing so.
Assuming you can recycle it now, you can also recycle it down the line when it genuinely isn’t worth keeping anymore. Until then, if you’ve got space, might as well. Because recycling isn’t free, in energy, emissions, or labor.
preserving lives and quality of life.
ROFL what? Continuing to use old panels in addition to new ones harms lives and quality of life? Ridiculous.
Solar panels can be recycled,
Most can’t, especially the old ones are glued shut.
I mean if you’ve got a low power thing at distance further than you want to run conduit. Or if you are in a hurry.
You’ve got to have space you want to use for them. Just because I have 10 200w panels for free doesn’t mean it makes sense to mount them on my roof (which is the only space I have facing the sun), because 400+w are available now and it costs money to mount them.
But it might not make sense to take down my 20 year old 200w panels and replace them, or maybe I can sell them to someone with more space.
Sure! That’s why I talk it might be critical for rooftop, but maybe useful somewhere else.
I’m pretty certain it may make economic sense to install something like this in a large open area. If the panels were meant to be thrown away, the price must be tiny.
Anyhow, I expect this to be more common once the mass-produced solar of the last decade gets old. We may just not be there yet to have plenty of used solar to offer.
My goal one day is to have enough yard space to do an on ground set up. Insanely cheap if you pick up some used panels. The average person would only need an electrician to hook it up to the house.
I understand not being comfortable with diy roof mounting, I know I’m not. The costs scale quickly when it goes on the roof
Ground mount has to address wind load which can be significant. I think the standard is around 500kg wind lift per standard panel. I’ve got a number of 200w panels I haven’t set up because I don’t have an inverter but also because they’re a pain to anchor.
I’ve never lived in areas with high winds. I’ve seen some people with very simple plywood frames to hold their panels. They’ve held for years without issue. Totally regional though
People get away with a lot, but as you note it’s regional. All it takes is one gust of wind.
But I do have a steady average 8kt wind (I mean average over last 5 years day and night), but gusts and storms push 50kt. I wish wind power was more accessible like solar has become; I live in an area that’s frequently the windiest in the country. I’d be able to use it as primary generation and solar for top off.
Looking at six solar arrays in Switzerland that have been running since the late 1980s and early 1990s, the team found most panels still produced more than 80% of their original power after three decades.
Temperature turned out to be a major character in the story. The study reports that lower-altitude systems faced higher thermal stress, with module temperatures reaching about 20 degrees Celsius warmer than high-altitude sites, and those hotter panels tended to degrade faster.
Some of the wear mechanisms were very specific but easy to picture. The encapsulant, the clear plastic layer that helps protect and hold the solar cells, showed more breakdown in hotter conditions, and the researchers linked that to chemical byproducts that can contribute to corrosion over time.
I wonder if new panels last even better, since there’s been more R&D done and manufacturers should have more experience now
Or worse because how to make.money selliing more panels, aka the enshitifcation of solar.panels.
That said I had some installed on my off grid solar cabin 20 yrs ago, 220w per panel, had some new panels installed on my small rural cottage late last uear, 370W per panel, same size panel, so that was sweet. I retired decades ago and run my home through the day on solar (hot wayer system only switches on to use solar thru the day, induction cooktop etc). and sell the excess solar to the grid, including charging my ecar off solar only.
I am not sure how this is new though, i’ve always worked on a 1%-2% degredation per year for panels, not a cliff like degradation.
Proofreading never killed anyone.
I highly suspect so. Chemicals are just so much better than they were in the past.
examined six grid-connected solar systems installed between 1987 and 1993 across different Swiss regions
tldr, ambient heat makes a huge difference. Switzerland doesn’t get that hot anywhere, and even less so in mountains.
But these are extremely old panels. Panels in 2020 started shipping with 40 and 50 year warrantees. But even panels that drop to 50% of original capacity, 60-100 years later, the best strategy for adding more power is more panels rather than ripping out and replacement. For a house, that can mean balcony solar, east/west, solar sheds, driveway awnings or solar RVs.
Three decades, three climates: environmental and material impacts on the long-term reliability of photovoltaic modules† https://pubs.rsc.org/en/content/articlelanding/2025/el/d4el00040d
the paper
