Sunpower positively grounded modules

[electro7]

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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[jaggedben]

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.

 

[ggunn]

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.

 

[electro7]

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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[pv_n00b]

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.

 

[tallgirl]

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.

 

[pv_n00b]

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.

 

[pv_n00b]

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/~he...ower/surface_polarization_effect_sunpower.pdf

 

[spoafnooss]

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!

Sent from my Pixel using Tapatalk

As I didn't see any reply regarding whether these specific panels work or not with transformless inverters, did you find any answer? (as I'm personally interested too) I would like to replace my broken SB3000HF inverter with a new one SUNNY BOY 3000 TL and I have the same Sunpower panels
SPR-320E-WHT-D

 

[jaggedben]

I'm pretty sure they will function. Whether they will maintain performance and whether it abides by Sunpower's warranty conditions would be things to look into.

 

[spoafnooss]

I'm pretty sure they will function. Whether they will maintain performance and whether it abides by Sunpower's warranty conditions would be things to look into.

Thank you, I was thinking the same. Panel warranty is not an issue (it's more expensive to ship panels from Greece to Sunpower for inspection than replace it with a new one). As for performance issues I will install it today and post the results in time, comparing them to previous years, to see if there will be any loss!

 

[jaggedben]

Thank you, I was thinking the same. Panel warranty is not an issue (it's more expensive to ship panels from Greece to Sunpower for inspection than replace it with a new one). As for performance issues I will install it today and post the results in time, comparing them to previous years, to see if there will be any loss!

The performance problem would likely take the form of faster power degradation over time, rather than an immediate hit with a new setup. A meaningful experiment on this would probably need to compare a few years worth of production data with the old and new inverters.

 

[tortuga]

When I do telco power supply/rectifier stuff they always wanted positively grounded systems, 48VDC Nominal. I forget the reasoning but they have done that since the telegraph days..

 

[Carultch]

When I do telco power supply/rectifier stuff they always wanted positively grounded systems, 48VDC Nominal. I forget the reasoning but they have done that since the telegraph days..

One possible factor that explains the reason for one type of ground vs the other, is the configuration of N-type and P-type semiconductors within critical components that rely on semiconductor technology. Such as transistors or in this case, the PV cells. The relative costs of both types of semiconductor doping will drive the selection of one polarity varient vs the other, in applications where either kind will work. It can have further implications on which polarity therefore needs to be grounded on a DC circuit.

What that means, is that the semiconductor material (suppose silicon) is treated with intentional impurities that bias different regions of the material for positive or negative charges available to conduct electricity. This is the fundamental reason why semiconductors are so useful in our tech economy. P stands for positive, and N stands for negative. A common dopant for P-type silicon is boron. A common dopant for N-type silicon is phosphorous. Don't let the fact that phosphorous starts with a P fool you, because that is an inconvenient coincidence.

 

[StarCat]

When I do telco power supply/rectifier stuff they always wanted positively grounded systems, 48VDC Nominal. I forget the reasoning but they have done that since the telegraph days..

Isn't this what Analog Telephone runs at? I knew an EE major back at University who said people used to hook up 4, 12V batteries in series and trickle charge them off the phone line back in the day......

 

[pv_n00b]

The purpose of the positive ground was to prevent PID. SunPower was one of the early manufacturers to talk about what would later be called PID. Their later modules do not require a ground. So your modules will operate ungrounded with a non-isolated inverter, but you may or may not see PID in the modules. Now PID will not shut down your system, it might reduce the output over time by a few percent.

 

[tortuga]

The purpose of the positive ground was to prevent PID.

Refresh my memory whats PID?

 

[Carultch]

Refresh my memory whats PID?

Potential induced degradation.

Potential refers to electric potential, which is the formal term in Physics for what we call Voltage. Specifically Voltage measured with respect to ground.

 

[pv_n00b]

Refresh my memory whats PID?

Depending on the design of the cells in the module, having them ungrounded can, over time, build up resistance in the module that reduces the output. It's more involved in that but that's a working approximation. The resistance that builds up can be reduced by bonding one of the module conductors to ground. SMA used to have a device that could be installed on an ungrounded array that would impress a voltage on the array overnight to reduce the effect of PID. Modern modules are designed to limit or prevent PID so it's not an issue.