Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

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HX_Guy
HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
in Solar Beginners Corner #1
Hope I'm not clogging up the forum with all my posts, I apologize if I am.

I'm not (seriously) considering these but I ran across an ad on Craigslist for SunPower panels, X20-327 panels for $200 and 425E panels for $260 and figured I'd bring it up for discussion. Called the guy and met with him earlier today, his business is basically refurbishing all sort of electronics and reselling them, including solar panels. He said he gets the laminated solar cell "sheets" directly from SunPower, that they are surpluses, which he then puts them into frames and sells. I took a look at the inventory he had...had tons of sheets stacked up and a few frames, which were a little scratched here and there (the frames) but overall looked good.

No factory warranty, obviously, but he said if a panel goes bad, he would replace it. I assume one can test the panel to make sure it's performing within specs prior to buying with a voltage meter?

I don't think the cost savings are worth the peace of mind of new + factory warranty, but it intrigued me. What are your guys' thoughts on it?

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
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    Re: Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

    Not a problem asking questions... We got lots of server capacity.

    Referb... I am a little surprised to see the full Sunpower label on the back. I would guess that the UL Listing would include the frame and any "factory" repairs (if needed). NRTL marks are usually removed/not useful on substantially modified/changed product.

    This may make the panels "legally" questionable for GT panels. Practically speaking--It is probably not a big issue for an off grid install.

    The other issue--Sunpower (if this is the same "Sunpower")--They have very high efficiency modules (relatively speaking). Their design caused them to be "sensitive" to charge build up based on reference voltages to earth ground:

    http://www.ftp.tognews.com/GoogleFiles/SunPowerPanels.pdf
    Introduction
    In August, 2005 SunPower announced the discovery of a new performance effect observed in
    high efficiency silicon solar cells. This new effect, called “surface polarization,” creates the nondestructive
    and reversible accumulation of static charge on the surface of high-efficiency solar
    cells such as the company’s all back contact A-300.
    The high efficiency of SunPower’s A-300 solar cell is obtained in part by covering its front
    surface with a proprietary coating which prevents the loss of the charge carriers generated by
    sunlight. This layer performs much like a transistor that is turned off, preventing current flow. If
    a large enough voltage is applied to the front of the cell, the “transistor” effectively turns on,
    allowing charge carriers to recombine at the front surface. When this happens, surface
    polarization reduces the output current of the cell. Also, like a transistor this effect can be fully
    reversed and current returned to the original level.

    Some of their panels say positive ground is not required... This manual referencing the "SPR" series seems to indicate positive grounding on Figure 5, page 9:

    http://us.sunpower.com/cs/Satellite?blobcol=urldata&blobheadername1=Content-Type&blobheadername2=Content-Disposition&blobheadervalue1=application%2Fpdf&blobheadervalue2=inline%3B+filename%3DManual%2BSPR-4600-5200.pdf&blobkey=id&blobtable=MungoBlobs&blobwhere=1300259004747&ssbinary=true
    WARNING: The SPR-4600-208 and SPR-5200-240 are configured for positive ground
    fault

    Does this requirement (if it is a requirement) apply to your panels? I do not know.

    For GT Inverters, positive grounding is "very easy". For Off Grid power systems, pretty much most systems assume negative ground and setting up as a positive ground may cause issues with electrical safety/grounding of signals, etc.

    I am not sure, but I believe that the higher the module is from negative ground reference, the "worse" the surface charging is... It is possible for a low voltage (one or two series panels, negative ground) may not have as much performance hit.

    -Bill "devil is in the details" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • HX_Guy
    HX_Guy Solar Expert Posts: 296 ✭✭✭✭✭✭
    #3
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    Re: Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

    The pictures I posted are from the Craigslist ad, I did not take them myself. The panels I saw in person had the same sticker, but the SunPower logo was cut off, so only 90% of the sticker was there showing the model number and specs. Some of the panels didn't have any stickers at all, but the panel itself looked the same.

    Like I said, I'm not really considering them...I doubt any installer would even want to get involved. These could be a good option for an off-grid system or DIY if someone knows what they are doing.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #4
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    Re: Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

    If you look around you can find new panels at this price, panels that you could also receive a 30% tax credit and connect to the grid... No Deal on these in my eyes!
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • jcheil
    jcheil Solar Expert Posts: 722 ✭✭✭
    #5
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    Re: Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

    I tend to agree. You can get new panels for about this same price with at least the "hope" of a warranty.
    Not to mention the positive grounding issue with off-grid can be difficult, especially if you are trying to add these to existing non-positive grounded panels or want to add some in the future. Not worth the hassle IMO.
    Also, not saying a big solar company is going to be in business longer than the guy on craigslist, but who knows. Warranties now-a-days are not worth the paper they are written on half the time.
    Off-Grid in Central Florida since 2005, Full-Time since June 2014 | 12 X Sovello 205w panels, 9 X ToPoint 220w panels, 36x ToPoint 225w panels (12,525 watts total) | Custom built single-axis ground mounts | Complete FP2 Outback System: 3 x FM80, 2 x VFX3648, X240 Transformer, FLEXnet-DC, Mate-3, Hub-10, FW500 AC/DC | 24 x Trojan L16RE-B Batteries 1110ah @ 48v | Honda EU7000is Generator and a pile of "other" Generators | Home-Made PVC solar hot water collector | Custom data logging software http://www.somewhatcrookedcamp.com/monitormate.html
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  • drraptor
    drraptor Solar Expert Posts: 218 ✭✭
    #6
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    Re: Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

    In Pakistan, Chinese panels without labels are available for as low as Rs 30/watt ~ $0.31 in winter. Obviously we don't have don't have Net metering enabled as of yet.
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  • ZoNiE
    ZoNiE Solar Expert Posts: 100 ✭✭
    #7
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    Re: Thoughts on refurbished solar panels? (SunPower for 61¢/watt)

    I came across a good price on these panels as well. New, SPR-240e-WHT-d panels for $0.75 per watt. I only need two, and will be putting them on a Trailer with basically a rubber roof on a wood frame. Nothing up there is grounded except the TV and Radio antenna's, and the Heat Pump is all plastic on the outside.

    The seller didn't know if they were Positive GND or not. I guess I can check that myself with a volt meter by measuring +V to the frame and -V to the frame and see what the polarity is? Or do the frames float? Are they connected that way, or is it up to me to ground the frame to ...something

    I looked at the link to the manual above, and yeah, the cheesy schematic shows +V to the GND bar.

    Does anyone here have experience with these panels? for $380, I can get the 480W in two panels which will fit perfect on my RV and have no shading whatsoever from all the other junk on the roof. The whole setup will be about $1.80 per watt with the charge controller, fusing, brackets, etc. Not a bad deal overall, and this includes a Midnight Kid.

    Cost does not reflect the GC2's which are already present, and good quality wire and cable which I already have gotten for free.
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