Are secondhand solar panels worth it?

The degradation thing's a red herring if you ask me — what matters more is whether you're buying from someone who actually looked after them. I've had my Fogstar panels on a static for five years now, picked up a pair of 250W Renogys secondhand when I expanded, and they're performing within spitting distance of spec.

The real killer is mystery panels. You get some dodgy 100W Chinese units off Facebook Marketplace with zero paperwork and you're basically guessing. Whereas @CotswoldNomad's Canadians? That's a known quantity. Those panels have proper datasheets and a reputation.

For emergency backup or off-grid living where you're not grid-tied, degradation is honestly less critical — you're not chasing peak output, you just need something reliable. I've got older panels doing perfectly adequate duty on a Victron setup in a caravan, running fridges and essentials. They're maybe 10-15% down on original output but that was baked into my system design anyway.

Just inspect the glass yourself, check for delamination, and if you can't find the installation history

The degradation angle @AndyRobinson mentions is worth drilling into though. Most quality panels lose about 0.5-0.8% annually anyway, so buying used doesn't fundamentally change that trajectory — you're just inheriting someone else's first few years of losses. What does matter is the panel's history. Were they installed in a harsh environment? How were they stored before sale?

I've got a mixed array with some older Canadians alongside newer stuff, and honestly the performance difference is negligible on my Victron monitoring. Where I'd be cautious is degradation beyond the normal curve — if you can get actual test data (IV curve measurements) from the seller, that's gold. eBay's a minefield for that though.

The real win with secondhand isn't the panels themselves, it's the money saved redirecting into a decent MPPT controller and battery bank. A £1,500 Lifepo4 setup will transform your system more than £500 worth of new panels. That's where people go wrong — they cheap out on panels but then run an undersized inverter or dodgy charge controller.

@Cot

Been through this myself — got a mixed batch of older Renogys for my static caravan setup three years back. You really need to know the panel history though. One batch I picked up had been sat in a damp barn for two years, and they're performing noticeably worse than the others.

The degradation @SueThompson mentions is real enough, but @FellKev's got a point about provenance mattering more. I'd rather buy secondhand panels with documentation showing they've been properly stored than roll the dice on mystery units.

What I'd add: check the frames for corrosion, look for delamination around the edges, and honestly, use an app to actually measure output if you can. Some "bargains" aren't if they're already on their way out. That said, for a cabin or static where you're not dependent on peak performance, secondhand quality panels from known manufacturers beat cheap new stuff every time.

The sweet spot seems to be panels 5-8 years old from established makers like Canadian Solar or Trina. Older than that and you're gambling.

Worth it if you're careful about sourcing. I picked up some Victron-adjacent bits secondhand and saved a fortune, but I'd always get a visual inspection first—dodgy frames or junction box damage aren't worth the headache. The real win is on budget builds like my narrowboat setup where new panels would've been prohibitive. Just factor in replacement costs if something fails.

The real gamble is whether you're buying ex-commercial stock (usually solid) or panels that've been sat in someone's garden for five years (dodgy). Insist on a degradation certificate if possible — cheap panels losing 2% annually ain't a bargain, they're a tax on your patience.

The degradation is usually minimal after the first year or two anyway. I've got a mix of secondhand 250W Canadas and newer stuff — the older panels perform about 80-85% of spec, which honestly isn't terrible given the price difference. Main thing is checking for delamination and microcracks before buying. @RetiredChef's right about sourcing; ex-commercial beats garage finds every time.