[RE-wrenches] Positive grounded arrays

[August Goers]

Hi Louis,

As Marco mentioned, this is a pain point for long term SunPower "friends."
First, we are still able to source isolated (transformer based) inverters
through SunPower. I think the last few we got were SMA Sunny Boys. That
seems like your best bet. I believe Enphase has a device that can ground
the positive DC conductor with their microinverters, but the last I checked
they weren't selling them.

I was told by a SunPower engineer a long time ago that when these old
modules are run ungrounded that they tend to produce about 50% less than
they should. The condition takes weeks or months to get worse and
eventually plateaus. If you then ground the array properly (to the positive
DC conductor) it will take a few weeks to start running well again, just as
Marco mentioned.

August


On Wed, Oct 14, 2020 at 1:05 PM <louis at solarcowboyz.com> wrote:

> Looking for feedback on the following, any help would be appreciated;
>
> Positive grounded arrays(Sunpower systems) what is being used as an
> Inverter replacement?
> Hard to get SMA's SBxxxxUS older style units that have the built-in
> POS/NEG grounding capability...
> As far as I know the newer line of Inverters from SMA will not work ; they
> are TL's and are not compatible.
>
> It would be tempting to "Un-Ground" the array and use the newer line of TL
> Inverters from SMA.
> The Discon would need to do both POS/NEG lines;OK
> I know of this being done with Arrays that are NEG grounded.
>
> How much of a Power loss from the array would be expected due to removing
> the POS ground on Sunpower panels and run them Un-grounded ?
> Guessing say 15 to 20% ?
>
> This may be a solution that the customer would go along with short of
> replacing the entire system.
>
>
>
>
> Best Regards
> Louis Segarra
> Tech Department/Field Operations
> Solar Cowboyz
> (530) 273-4895
> (916) 212-0282
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