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Thread: Sunpower positively grounded modules

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    Sunpower positively grounded modules

    Was wondering if anybody can help me understand the sunpower positively grounded modules?

    I am assuming it is a way they manufactured the solar cell. I understand also with the older transformer style inverters the inverter manufacturer needed to make an adjustment internally to be compatible.

    Can the positively grounded modules work with the transformerless inverters? Can they work with solaredge optimizers, does anybody know?

    Thanks ahead of time for your help and input!

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    I believe the issue is module degradation. My understanding is also that a few years ago Sunpower made a change and that newer modules really don't need to be positively grounded. I have put older modules on optimizers on an ungrounded system because, well, I had a situation with no other real option. The system worked fine, although I haven't kept track of its performance.

    You should probably just contact Sunpower for more detail.

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    Quote Originally Posted by jaggedben View Post
    I believe the issue is module degradation. My understanding is also that a few years ago Sunpower made a change and that newer modules really don't need to be positively grounded. I have put older modules on optimizers on an ungrounded system because, well, I had a situation with no other real option. The system worked fine, although I haven't kept track of its performance.

    You should probably just contact Sunpower for more detail.
    Nothing made by SunPower for at least the past 3 1/2 years has needed positive grounding. That's how long I have been in my present position, and 95+% of what we sell is SunPower.

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    SPR-320E-WHT-D is the model number. (Nothing on the name plate or spec sheet notify whether they are positively grounded or not). They may be older modules?? I don't know the manufacturing date but I'm going to find out. I gave solaredge the model number and they said they are compatible. The guy who has them says they are positively grounded modules.

    So, it sounds like you are saying Sunpower with some of their older modules manufactured them in a way that they needed to be positively grounded in order to keep the cell degradation rate down? If these same modules where connected negatively grounded they would work (?) but the cell would degradate faster?

    If that's the case I wonder (if they are positively grounded) what the degradation rate would be being connected to an ungrounded inverter.

    I'm also going to take your advise and contact Sunpower.

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    The SPR-XXXE-WHT-D is listed as a legacy module in the SunPower installation manual and it needs to be positively grounded. It says that if it's not grounded there will be reduced performance and it will invalidate the warranty. I believe the positive ground gave the modules a 1% performance boost, which at the time was a big deal.

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    Quote Originally Posted by pv_n00b View Post
    The SPR-XXXE-WHT-D is listed as a legacy module in the SunPower installation manual and it needs to be positively grounded. It says that if it's not grounded there will be reduced performance and it will invalidate the warranty. I believe the positive ground gave the modules a 1% performance boost, which at the time was a big deal.
    There was a problem with negative grounding causing "Potential Induced Degradation" on some panels. Feel free to hit up Google for more details.

    SunPower's performance boost came from how their cells are constructed -- they don't have the contact wires in the front. I had a few raw SunPower cells at one time and their construction was completely different from traditional cells.
    Julie in Austin

    Born to brew, forced to work ...

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    Quote Originally Posted by tallgirl View Post
    There was a problem with negative grounding causing "Potential Induced Degradation" on some panels. Feel free to hit up Google for more details.

    SunPower's performance boost came from how their cells are constructed -- they don't have the contact wires in the front. I had a few raw SunPower cells at one time and their construction was completely different from traditional cells.
    They got a boost from being positively grounded, with their specific design it reduced the resistance slightly and allowed more electrons to get out of the cells. It was not specifically to reduce PID, although that was a bonus. Back contacts also increased the efficiency, in a different way and in addition to the boost from being positively grounded. Sunpower had a white paper out on the effect of positive grounding at one time but since this is old technology for them it might be hard to find now, even on Google.

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    Come to think of it I wonder if the "surface polarization effect" SunPower was talking about was PID? I'm not a physicist so I get a little lost in the deeper descriptions of PID. I did find this paper on the SunPower surface polarization effect from 2005. That was when SunPower made a big announcement about discovering this effect and that they had a secret way to fix it that they were patenting. I had thought this was a separate issue having to do with their specific cell design, they certainly made it sound that way back in 2005.
    https://physics.oregonstate.edu/~het...t_sunpower.pdf
    Last edited by pv_n00b; 04-26-19 at 06:02 PM.

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