Used Solar Panels

[CCHQ]

I read MMM's most recent article on installing a heat pump, which sent me down the rabbit hole of his DIY solar installation. I went and priced it out for my own application in central Ohio, but the ROI just didn't make sense.

But then it occurred to me "Couldn't I buy the panels used?"

Has anyone around here done that before?

[dandarc]

There is this guy on Ebay selling used 250W panels:
https://www.ebay.com/itm/372614945473

Note the shipping adds quite a lot to the cost - if you bought 20 of them still looking at at least 25% over the base price with shipping. Still quite low $per watt, but there's a bunch of other stuff you'll need to install them.

[Watchmaker]

Degradation of PV panels is real, so it's important to understand how used the panels you're buying are. Two years old and never put into the field would be very different than 10 years old and having just been pulled from someone's roof.

[uniwelder]

In a diy setup, new panels will probably be half your total install cost. If you got used panels at half price per watt ($0.25 vs $0.50), you’re only looking at a 25% total savings for something with no warranty that will take up more square footage due to lower efficiency, which can be important.

If you want to do some easy price comparisons, go to altestore.com
Their pricing is very transparent and have good educational videos and tools.

[zolotiyeruki]

Paging @Syonyk ......

[CCHQ]

In a diy setup, new panels will probably be half your total install cost. If you got used panels at half price per watt ($0.25 vs $0.50), you’re only looking at a 25% total savings for something with no warranty that will take up more square footage due to lower efficiency, which can be important.

If you want to do some easy price comparisons, go to altestore.com
Their pricing is very transparent and have good educational videos and tools.

But 25% savings on a $12,000 system is $3,000. That’s not nothing. Just looking at alternatives.

[Syonyk]

I went and priced it out for my own application in central Ohio, but the ROI just didn't make sense.

What did you end up with for pricing on the system?  Should be in the range of $1.25-$1.50/W for a DIY install with new panels.

But then it occurred to me "Couldn't I buy the panels used?"

You could, but it's far from clear that it will actually save you money when you factor in balance of system costs.

In general, used panels are cheaper, but they're also degraded (to some unknown and unlikely to match each other extent), and tend to be far lower power than a modern panel.

For strings of panels in series (not using per panel optimizers), the string will operate at the current of the lowest panel in the string - so if one has degraded a bit more than the others, that will limit the power of the whole string.  If you have optimizers, you can get around that, but are now buying per-panel electronics at a significant chunk of change.  If you go with microinverters, you're now having to buy quite a few more for a given system size, and will be running them a good bit lower than rated power, which means you're paying for inverter capacity you're not using.  Nothing wrong with that, I don't like running power electronics at full output (my 6000VA inverters rarely pass more than about 4500VA), but it adds cost with microinverters.

A few other possible concerns with used panels, depending on the source:
- If they're not UL listed to current standards, they may not meet code requirements - which may make them not legal to install on a structure.
- I don't know if used equipment qualifies for the ITC credit.  Now, in practice, nobody is going to check, but if the requirements explicitly require new panels, you can't (shouldn't?) claim them for that.  I'm certain there's plenty of tax fraud around that the IRS doesn't care to catch, though - it's just a single line item.

If you can, you might want to grade the used panels - hook them up to a MPPT controller with an infinite sink (compared to the panel output) and check max output.  Also check open circuit voltage and, if you can, short circuit current.  That will let you cull out any really weird ones.

But I'm still just not convinced you'll end up much different on costs - and it may very well be higher for a set of used panels.

If you have 80% capacity 250W panels (200W panels, effectively), vs 330W panels, you'll need 65% more panels for the same system output - which, handwaving a bit, means about 65% more balance of system costs.

So do the math fully before you decide they're a huge savings.  The panels no longer dominate installed cost.

[CCHQ]

I went and priced it out for my own application in central Ohio, but the ROI just didn't make sense.

What did you end up with for pricing on the system?  Should be in the range of $1.25-$1.50/W for a DIY install with new panels.

But then it occurred to me "Couldn't I buy the panels used?"

You could, but it's far from clear that it will actually save you money when you factor in balance of system costs.

In general, used panels are cheaper, but they're also degraded (to some unknown and unlikely to match each other extent), and tend to be far lower power than a modern panel.

For strings of panels in series (not using per panel optimizers), the string will operate at the current of the lowest panel in the string - so if one has degraded a bit more than the others, that will limit the power of the whole string.  If you have optimizers, you can get around that, but are now buying per-panel electronics at a significant chunk of change.  If you go with microinverters, you're now having to buy quite a few more for a given system size, and will be running them a good bit lower than rated power, which means you're paying for inverter capacity you're not using.  Nothing wrong with that, I don't like running power electronics at full output (my 6000VA inverters rarely pass more than about 4500VA), but it adds cost with microinverters.

A few other possible concerns with used panels, depending on the source:
- If they're not UL listed to current standards, they may not meet code requirements - which may make them not legal to install on a structure.
- I don't know if used equipment qualifies for the ITC credit.  Now, in practice, nobody is going to check, but if the requirements explicitly require new panels, you can't (shouldn't?) claim them for that.  I'm certain there's plenty of tax fraud around that the IRS doesn't care to catch, though - it's just a single line item.

If you can, you might want to grade the used panels - hook them up to a MPPT controller with an infinite sink (compared to the panel output) and check max output.  Also check open circuit voltage and, if you can, short circuit current.  That will let you cull out any really weird ones.

But I'm still just not convinced you'll end up much different on costs - and it may very well be higher for a set of used panels.

If you have 80% capacity 250W panels (200W panels, effectively), vs 330W panels, you'll need 65% more panels for the same system output - which, handwaving a bit, means about 65% more balance of system costs.

So do the math fully before you decide they're a huge savings.  The panels no longer dominate installed cost.

Hey @Synoyk - thanks for that very thorough reply.

I figure I’d have to use microconverters anyway. Local codes say I can’t use string converters on the roof of a house (at least as I read them), and I have a fair amount of shade to deal with.

So, let’s compare these two:

New Phono Solar 400W @ $276 - https://www.gogreensolar.com/collections/solar-panels/products/phono-400w-144-cell
Used CSUN 250W @ $48 - https://store.santansolar.com/product/csun-250w-snail-trail/

I’d need roughly twice as many used panels as the new ones, but I’m still paying a $176 premium for those new panels. So, for 16 panels, that’s a price difference of about $2,800.

I’m sure I’m not calculating things correctly somewhere.

[RWD]

So, let’s compare these two:

New Phono Solar 400W @ $276 - https://www.gogreensolar.com/collections/solar-panels/products/phono-400w-144-cell
Used CSUN 250W @ $48 - https://store.santansolar.com/product/csun-250w-snail-trail/

For starters the new panels have a 12/25 year product/performance warranty versus 1 year warranty for the used panels...

[uniwelder]

Syonyk brought up a good point--- used equipment doesn't qualify for the 26% federal tax credit.

Also you mentioned string inverter vs micro.  In Virginia, there's a new regulation that requires some kind of de-energization of panels if power goes down at the house.  This is different than the safety that prevents power going to the grid to protect linemen.  Its purpose is to protect firefighters or other emergency personnel that might be on your roof.  Any string inverter system now needs an additional module added to each panel, so they're supposedly not as cost effective anymore vs micro inverters.  Is it possible this is why you mention string inverters not being allowed in your area?

The panels you're pricing out in your last example are probably more expensive ($0.69) per watt than necessary.  Here's a diy system from altestore--- https://www.altestore.com/store/solar-power-systems/grid-tie-solar-power-systems/grid-tie-528kw-solar-power-system-with-enphase-p41503/  Total cost is $7,100 and has 16 panels you mention in your previous example that purchased individually cost $0.59/watt.  They're lower wattage than the panels you mention, but the micro inverters are going to cut off their output anyway, so you'll get almost equivalent power with 365 watt panels vs 400 watt.

edited to add--- if you're using micro inverters, you're also paying for all those extra modules for each panel.  Add in another $150 or so to each used panel to account for the module plus extra racking.  For the example you gave, the $176 premium now becomes $26 for new panels.

edited again to fix some formatting and wording

[CCHQ]

Syonyk brought up a good point--- used equipment doesn't qualify for the 26% federal tax credit.

True, and it's a very good point. But after the EIC and other tax reductions, there's not much left in my tax return to get a credit on.

Also you mentioned string inverter vs micro.  In Virginia, there's a new regulation that requires some kind of de-energization of panels if power goes down at the house.  This is different than the safety that prevents power going to the grid to protect linemen.  Its purpose is to protect firefighters or other emergency personnel that might be on your roof.  Any string inverter system now needs an additional module added to each panel, so they're supposedly not as cost effective anymore vs micro inverters.  Is it possible this is why you mention string inverters not being allowed in your area?

Maybe? I'm not sure on the specifics. I know there's now power optimizers, which might be what you're referring to. I feel a bit like I'm grasping here.

The panels you're pricing out in your last example are probably more expensive ($0.69) per watt than necessary.  Here's a diy system from altestore--- https://www.altestore.com/store/solar-power-systems/grid-tie-solar-power-systems/grid-tie-528kw-solar-power-system-with-enphase-p41503/  Total cost is $7,100 and has 16 panels you mention in your previous example that purchased individually cost $0.59/watt.  They're lower wattage than the panels you mention, but the micro inverters are going to cut off their output anyway, so you'll get almost equivalent power with 365 watt panels vs 400 watt.

Hmm... yeah, you're right. I think I just pulled the cheapest per watt panel from a random solar company and didn't take the time to look further.

edited to add--- if you're using micro inverters, you're also paying for all those extra modules for each panel.  Add in another $150 or so to each used panel to account for the module plus extra racking.  For the example you gave, the $176 premium now becomes $26 for new panels.

edited again to fix some formatting and wording

Oh, right. So, it's not just the cost of the panel, it's the cost of the panel + microconverter...

[dandarc]

The solar tax credit can carry forward, plus with planning you might be able to do something like a tax-free Roth conversion if you don't think you can claim the whole credit. Of course do draft tax returns to see if there are any other "gotchas".

[Ripple4]

I read MMM's most recent article on installing a heat pump, which sent me down the rabbit hole of his DIY solar installation. I went and priced it out for my own application in central Ohio, but the ROI just didn't make sense.

But then it occurred to me "Couldn't I buy the panels used?"

Has anyone around here done that before?

I bought used solar panels from santan, and am in Ohio, also have a heat pump, and am on this forum. The santan links so far in this thread are for panels with the labels removed and have oxidation damage inside the EVA layer. some of the 'best' deals are for ones with the vinyl backing with splits in it, they wont last. That store also sells better panels, sometimes new ones.  keep in mind that no-label panels cannot be used for grid-tie, they need a label for this. no-label panels fine for off-grid like what I did. I like double glass bifacial panels now, with what I have learned after 2+ years of solar power. i suggest looking at these: https://realgoods.com/canadian-solar-hiku-solar-panel-440w-cs3w-440ms

I don't understand if there is a limitation on solar tax credits. deductions have limits, because it reduces the net income that your taxed on and can't go less than nothing, but as I understand it, credits are 1:1 to your refund.

 

[BudgetSlasher]

It seems everyone has done a good job of mentioning issues that used panels will more than likely have, so I'll just add this.

I would be wary of used, in the sense of installed and removed panels. These are systems that are meant to sit quietly and generate power for decades (typically warranty is something around output of 90% @ 10yrs and 80% @ 20yrs), so why are used panels on the market in the first place? There first installation was a failure, what says their second will be any better. There may be some "used" panel that were bought and never installed, such as purchased by the pallet and had a partial pallet leftover, or purchase but never installed.

Back when I was considering solar there were options for "B" stock panels with some form of imperfection.

[gooki]

One source of used panels is leased solar systems. The home gets sold, and the new owner doesn't want to take over the lease, so the solar system is removed.

The unfortunate reality is the source of the used panels isn't always known.

[NorCal]

I may or may not have ~3kW worth of panels with Enphase micro inverters to sell in a year or so in the Denver area.

Our roof is nearing the end of its life.  Enphase is offering us a 50% discount on materials to upgrade our old panels and inverters to their newer technology.  It may pencil out to sell the old panels (if they don't require me to give them back as part of the deal) if I have to take them off the roof anyways.

I'd be open to parting with them relatively cheaply for someone local if I end up going for the upgrade.