Picked up a cheap 200W panel from Facebook Marketplace — worth it or a gamble?

Facebook Marketplace panels are basically the Schrodinger's Cat of solar — you don't know if it's alive until you plug it in. 🐱⚡

Done this twice myself for the cabin setup and honestly the hit rate is better than you'd think, if you know what to look for before handing over the cash.

Few things I always check on collection:

• No hotspots — grab a thermal camera app on your phone (not perfect but catches the obvious horrors)
• Check the junction box — if it's been left outside for years, that seal cracks and moisture gets in, and then you've basically bought an expensive garden ornament
• Test the Voc on the spot — chuck a cheap multimeter in your bag, sunny day should give you a reading close to the panel's spec sheet
• Frame integrity — bent or cracked frames from dodgy mounting are a massive red flag

My second one had a slightly iffy junction box seal but I resealed it with some self-amalgamating tape and it's been happily feeding my Victron MPPT for 18 months without a moan.

The real gamble isn't the panel — it's whether the seller actually knows what they're selling. "Hardly used, belonged to my dad" could mean anything from pristine to "sat in a field since 2009."

Worth it? Usually yes at 200W for under £60. Just don't go in blind.

Anyone else got a Marketplace horror story or a bargain triumph? Genuinely curious whether the luck holds across the board or if I've just been fortunate. 🤞

@SolarNut bought three "200W" panels off Facebook and turns out two were closer to 140W — my Victron MPPT told no lies, even when the seller did. 🔍

@RetiredNurse49 ha, the Victron never lies, brutal but useful 😄

Done this with my narrowboat setup — grabbed two panels off Marketplace last spring. One was legit, one was clearly a degraded ex-commercial panel, proper scratchy cells underneath. Still works but nowhere near rated output.

Top tips if you're buying:

• Check the frame — bent corners = rough life
• Shine a torch across the surface for microcracks
• Test Voc immediately with a cheap multimeter, should be close to the sticker spec
• Haggle hard — anything over £40-50 for an unknown 200W is risky money

For emergency backup or a garden office it's honestly fine as a gamble. For a narrowboat where you're depending on it? I'd mix with at least one known-good Renogy or similar alongside it.

@RetiredNurse49 that's the classic Facebook "optimistic wattage" problem — sellers often just repeat whatever the previous owner told them, Chinese label and all 😄

Before I commit to any marketplace panel I always do a quick open-circuit voltage check with a multimeter in decent sunlight. If a claimed 200W panel isn't showing roughly 20-22V Voc on a bright day, I'm walking away or renegotiating the price sharpish.

Also worth checking the junction box on the back — cracked or water-damaged ones are a red flag, especially up here where panels spend half their lives rained on.

That said, even a genuine 140W panel at the right price can be solid value. Just go in with realistic expectations rather than the seller's optimistic specs. 👍

@SolarNut great thread! I'd add that before you even plug it in, a quick visual inspection tells you a lot — look for microcracks by holding it up to bright daylight at a low angle, and check the junction box for any signs of water ingress or dodgy DIY soldering. Also worth noting the cell colour consistency; badly faded or mismatched cells are a red flag.

If you've got a basic multimeter, measuring open-circuit voltage in full sun takes about 30 seconds and immediately tells you if something's seriously wrong. Won't catch every issue but it filters out the obvious duds before you've wired anything up properly.

Bought a couple of marketplace panels myself last year — one was genuinely cracking value, one was borderline. Swings and roundabouts really, but going in with a checklist rather than blind faith makes the gamble considerably more manageable. 👍

@ILK_Marine good point on the visual inspection — I'd extend that to checking the junction box on the rear. Delaminated or cracked junction boxes are a red flag; moisture ingress there kills panels slowly and you won't see it in the IV curve until it's already degraded significantly.

Had one on the motorhome that tested fine initially but the J-box seal had failed. Two seasons later the output had dropped noticeably. Pulled it off and the bypass diodes were corroded through.

Worth noting: a basic clamp meter and a sunny day will tell you a lot, but for proper verification you really want to measure Voc and Isc separately and compare against the datasheet. Most secondhand panels won't come with one, so search the model number — manufacturers usually host them.

Budget panels can absolutely be worth it. Due diligence isn't optional though.