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Opinions on Used Solar Equipment

Catsassend

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Jun 9, 2021
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What are your opinions on buying used solar equipment?
If solar panels are cheap enough and my space to use them is unlimited (so I could add more panels to produce the energy that I need), is it okay to buy someone's old and deteriorated panels? Will they still produce enough to make them usable? Is there an unwritten expiry date on panels?
Is there any chance that they have been made to produce absolutely no current? (Burned out somehow?) If so, should I test for this, with a multi-meter?
Or should I just bite the bullet and pay for everything brand new?
 
I bought some 295w panels (from Santan Solar) that had been on a solar farm for 6-7 years (as I recall). They make about 250w on a good day and will get up to 290w if cool and breezy. They were $60 each a couple of years ago. If they were "deteriorated" in performance (very much), I would stay away from them unless they were free. Mounting is just too hard/expensive. But 90% of original rating at 50% of the price...yes I would.
 
I bought 40 panels from Santan Solar - https://www.ebay.com/vod/FetchOrderDetails?itemid=373263844597&transid=1270530599024&ul_noapp=true Advertised as 9yr old - pulled from a system upgrade - so we agreed (before purchase) that they'd have at least 90% of original power left. I tested them against a brand-new 285w panel - and 39 passed at 95%'ish. The test was voltage and amps check between new and these (same sun, same angle, same time).

1 panel had a bad diode pack that was revealed by voltage check and I had to replace ($10 + hour).
1 panel had smashed glass on arrival.

39 out of 40 - overall - was pleased.
 
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Quality used is good, and can save 50% to 75% of the cost.

Some PV panels degrade faster than others, so quality counts.
Simple DMM can measure Voc and Isc. Good to cover panel or turn away from the sun when connecting/disconnecting ammeter to prevent arcs.
Imp is more difficult to measure. But it is more perceptive to degradation from "PID".
If a diode goes bad, open circuit would not be seen in these tests while short-circuit would be.

PV panels are so cheap these days, consider paying more for panels that produce power watts per unit area. That saves space, labor, mounting hardware.

There are quality inverters worth considering used or new-old-stock as well. But for grid-tie, you may be required to have one with latest features.
 
Here is a sample of what came up. "Used 2 years, 3500 watt sunny boy inverter 40 used panels and 12 new Includes some wiring" for $2000 CAD. These are Kaneka 60W panels. Would this be a good starting point for a cabin.
 
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I bought some used Astronergy panels (said to be 1 year old) for 55$ each. Wired them up and tested them with perfect alignment to the sun. I got 94% of rated output. I was thrilled! Better percentage than the Renogy panels I paid retail for.
 
I bought some 295w panels (from Santan Solar) that had been on a solar farm for 6-7 years (as I recall). They make about 250w on a good day and will get up to 290w if cool and breezy. They were $60 each a couple of years ago. If they were "deteriorated" in performance (very much), I would stay away from them unless they were free. Mounting is just too hard/expensive. But 90% of original rating at 50% of the price...yes I would.
Wish I could get panels from the USA. Great Prices.
 
Quality used is good, and can save 50% to 75% of the cost.

Some PV panels degrade faster than others, so quality counts.
Simple DMM can measure Voc and Isc. Good to cover panel or turn away from the sun when connecting/disconnecting ammeter to prevent arcs.
Imp is more difficult to measure. But it is more perceptive to degradation from "PID".
If a diode goes bad, open circuit would not be seen in these tests while short-circuit would be.

PV panels are so cheap these days, consider paying more for panels that produce power watts per unit area. That saves space, labor, mounting hardware.

There are quality inverters worth considering used or new-old-stock as well. But for grid-tie, you may be required to have one with latest features.
Thank you for the information, and for the safety tip.
 
Is it difficult to mount panels?
If they are 2nd hand and free, as they are here in Australia if you know where to look, just start standing them up against the wall or hang them from a fence and progress from there.
There are plenty of examples of frames on this site.
 
I'd have no problem buying used panels because those are easy to inspect visually and get a voltage and amp check.

If the exact voltage and AH was for sale on a single ad, I may consider those. FLA batteries are fairly easy to test with a hydrometer, and the others you can voltage check, but that may not be the most accurate.

For all the other equipment, I'd be less willing. I've seen some complete set ups for sale and some of the old inverters and converters are not what is on the market today the pics made them quite worn for their age.
 
Wish I could get panels from the USA. Great Prices.

Is it an import duty issue?

Maybe you can. I got some inverters from Canada, shipped to US. Because they were made in Canada, the free trade agreement avoided duties.
There are some US made panels. Some are either made in Canada, or are products of a Canadian company (I think) "Canadian Solar" (if that makes any difference.)
 
Is it difficult to mount panels?

Well, let's say you got 10 panels for 600 watts. Or you could get 2 panels for the same wattage. With the 60W panels you have 20 wires that need to be combined. With the second, 4 wires. Each panel needs to be supported around the edges. Draw up a grid of 10 VS a grid of 2. And while you can just lean panels against something the first time bad weather comes in you may be crying. So while mounting panels isn't difficult per se, I think with the 60 watt panels that the juice ain't worth the squeeze.
 
Here is a sample of what came up. "Used 2 years, 3500 watt sunny boy inverter 40 used panels and 12 new Includes some wiring" for $2000 CAD. These are Kaneka 60W panels. Would this be a good starting point for a cabin.

"Cabin" as in off-grid?

A Sunny Boy is a grid-tied inverter, won't make power without being fed by a grid. (Except, it may have a PV direct backup outlet that makes up to 2kW AC while grid is down, no battery storage.)

If you also get a Sunny Island (actually two of them, or one of the plus a 120/240V transformer) and a 48V battery, that will make a local grid that works with Sunny Boy.

This is what I have as a grid tie & (off grid) backup system. Very good but rather expensive. Better for building a 10kW system not just 3.5 kW.

If you are on-grid, then it would be good. So long as the Sunny Boy has the features required for permits and utility agreements (which change periodically.)

You can probably find either an older battery inverter plus PV charge controller, or maybe a hybrid PV/battery inverter new and cheap. I don't know how good the cheap ones are but there is a wide range of price points. Probably use 48V battery, unless about 3kW AC is all you'll ever need in which case 24V could be OK.


My panels are 120W (from 17 years ago), 165W, and 327W.
 
"Cabin" as in off-grid?

A Sunny Boy is a grid-tied inverter, won't make power without being fed by a grid. (Except, it may have a PV direct backup outlet that makes up to 2kW AC while grid is down, no battery storage.)

If you also get a Sunny Island (actually two of them, or one of the plus a 120/240V transformer) and a 48V battery, that will make a local grid that works with Sunny Boy.

This is what I have as a grid tie & (off grid) backup system. Very good but rather expensive. Better for building a 10kW system not just 3.5 kW.

If you are on-grid, then it would be good. So long as the Sunny Boy has the features required for permits and utility agreements (which change periodically.)

You can probably find either an older battery inverter plus PV charge controller, or maybe a hybrid PV/battery inverter new and cheap. I don't know how good the cheap ones are but there is a wide range of price points. Probably use 48V battery, unless about 3kW AC is all you'll ever need in which case 24V could be OK.


My panels are 120W (from 17 years ago), 165W, and 327W.
I saw things about "grid-tied" but didn't know it would matter, and then I didn't think about that while looking at the used equipment. We won't be tied in to the grid, it will waste a lot of money paying to bring the line in 2750 feet from the road. We definitively plan to be total off the power grid.
 
In that case "grid tie" inverter is useless for you, unless it interacts with other battery equipment as part of an off-grid system. Typically that's for larger, higher power systems.

What you want for an inverter depends on what you need to power. Something like an induction motor in a well pump requires huge surge current to start. Typically we say to use a low-frequency inverter with heavy transformer for that, but some high frequency inverters quote significant surge current for many seconds. Other loads are easy to power with cheap high frequency inverters.

We see some all-in-one inverters under $1000 with 48V battery input, PV input, 5kW rating. Some quality brands are in the $3000 to $5000 range. So there is a wide price range available, you may get by inexpensively or you might spend serious money, depending on what you want.

Got space for a car trailer? There may be some DC Solar trailers available around $8000. That gets you two 6 kW Sunny Island (MSRP $5000 each), two GNB forklift batteries (MSRP $5000 each, make sure they're still in good shape), one Midnight charge controller, 2400W of PV. That's a very capable system except relatively small PV array. I would add one or more Sunny Boy with PV panels.

You can probably spend as little as $1000 on a system with 12V battery, up to $20k or so.
If you get a deal on a used 12V off-grid inverter, consider batteries in parallel and a charge controller that supports 12V/24V/48V so you can upgrade just the inverter and reconfigure the rest.

And batteries - lead acid FLA or AGM are simple, but have limited lifespan (1 year to 10 or 15 years, depending on type and how shallow they are cycled.) Commercial lithium assemblies are expensive. DIY LiFePO4 looks quite attractive pricewise and should last 10 years, but is a project itself. Consider using a charge controller that has setting you can customize for LiFePO4 even if you start out with a lead-acid battery.
 
it will waste a lot of money paying to bring the line in 2750 feet from the road. We definitively plan to be total off the power grid.
You can probably spend as little as $1000 on a system with 12V battery, up to $20k or so.
A lot of times running that line may not be as expensive as it looks. Especially if there' frequent high wattage loads like AC to be powered.
 
If multiple parcels would share the cost of line, could be more reasonable.
If your property is large (extends to or near road) and cost to bring power to property line is affordable, you can extend more cheaply. Just 12 awg (either strung between trees or run in conduit above/under ground) would provide a lot of power 24/7 to keep a battery charger/inverter going.
 
We are not going to be able to share the cost of line, it's our land. We want to build by the ocean, the distance is over 2750 feet as the crow flies, but well over 3150' following the driveway, and traversing a swampy area (over or under), plus it is very rocky (Nova Scotia coast) and it is a well treed lot. There is already a tiny one room cabin there and we will be putting a small RV there to stay in, while we build our house. Nova Scotia Power will cover the cost of 92M (302') of line and poles and then we would be responsible for at my estimate would be at least 869M (2850 feet) of line. The last time we put power to a house was over 30 years ago (as I remember it) at $8 per meter. I expect that cost to be at least triple now, so just for that line I estimate t would cost $20,856 then we still have to either put in the additional poles or trench. Nova Scotia has one of the highest electricity rates at an average of $0.17 /kwh and I'm not even sure if that price includes the cost of delivery or sales tax! So producing our own power closer to our house is something we really need to do.

I would like to get either buy a whole system that we could use in the cabin and RV and then hook up to our house once we build. I guess ideally, with the help I am getting here, we should buy a new controller, and inverter, and we could get by with some good used panels and batteries. Our electricity needs are for electronics, washer, fridge, freezer, water heater, and electronics. We are expecting to use a shallow well pump, it would be nice to have that work with electricity but we could look at doing that with a generator. ( We are already used to transporting and storing water but that's a whole other issue. )

Is a transformer different than an inverter?
 
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