Sunpower Solar Install Help

[s/v Holiday]

Well I think I am in over my head a bit on this one.

I found a really good deal on 8 new Sunpower X21-345w panels so I jumped on it and bought them. Well I come to find out that these panels require a positive ground (apparently all Sunpower panels require this).

I also purchased 2 Midnite Classic 150 MPPT charge controllers and Midnites combiner box and all necessary breakers.

I have been researching this on the internet but have found no good solutions for an off grid 12v battery system.

Does anyone out there have experience with a similar setup? I have seen posts in the past referring to Sunpower panels on boats so there must be a safe way to accomplish this.

Any help or direction would be greatly appreciated.

Cheers,
CJ

[senormechanico]

The Midnite Solar 150 can be used with positive ground.
I have one on my house's grid intertie.
Are you going to use this for a boat or house?

After looking at the data sheet for the panel, I don't see any referral to the need for positive ground.

http://us.sunpower.com/cs/Satellite?...&ssbinary=true

[s/v Holiday]

Hi yes, sorry it is for my boat.

This is the problem as the rest of the boat is Negative grounded.

I did not see it listed on the data sheet as well but when I when to purchase the charge controller I was told that all sun power panels use a positive ground. When I started looking into it it turns out that all sun power panels use a positive ground to recover the surface charge of the cells of the panel.

Cheers,

CJ

[dlentz]

Originally Posted by s/v Holiday

Hi yes, sorry it is for my boat.



I did not see it listed on the data sheet as well but when I when to purchase the charge controller I was told that all sun power panels use a positive ground.

Cheers,

CJ

I don't believe that's the case for the newer panels. They changed a while back.
Dwain

[djmarchand]

The requirement of a positive ground is new to me. But does the controller care what the ground situation of the panel is? You do need to isolate the panel's ground from the boat's grounding system as I suspect that the controller doesn't isolate the grounds. But if it does, then you don't even need to worry about that.


If the controller does isolate the grounds, then t would be like the controller representing two sides of an isolation transformer. The ground on one side doesn't care about the ground on the other side.

[gspeak]

As I understand, earlier Sunpower panels were positive ground, & even then I have read that a few boat installations got around this with some creative wiring.

They changed positive ground requirement for the latest panels (from the E20 327W model), or they offer both versions. I would have thought that the X21-345w being the latest available, would also not have this requirement, though I can't confirm this.

We have had a E20 327w hooked up on Seabreeze for over a year now that does not have this requirement. We hooked ours up with a Morningstar Tristar MPPT 60.

The Sunpower panels are exceptionally efficient & well built. Be aware though that they do not warrant for boat installations, at least here in Oz.

Dave

[F51]

We just installed 2 Sunpower X21-345w panels with a Morningstar TS-MPPT-80 controller. Our boat is negative ground. Everything works fine. The Morningstar manual did say that you could not use their controller on a positive ground system. I don't believe the Sunpower panels would care since both positive and negative cables come off the panels-how would they know which system ground you have? Maybe someone with direct knowledge can correct me if I'm wrong. :-)

[senormechanico]

I seriously doubt the frames are connected in any way to the cells.
My twelve Panasonic 240 watt home's panels weren't.

[s/v Holiday]

Originally Posted by dlentz

I don't believe that's the case for the newer panels. They changed a while back.
Dwain

That would be great news but I have not been able to find anything that says they have changed.

I have sent an inquiry to sun power but I don't expect an answer as I am not a authorized installer.

Thanks

CJ

[s/v Holiday]

Originally Posted by F51

We just installed 2 Sunpower X21-345w panels with a Morningstar TS-MPPT-80 controller. Our boat is negative ground. Everything works fine. The Morningstar manual did say that you could not use their controller on a positive ground system. I don't believe the Sunpower panels would care since both positive and negative cables come off the panels-how would they know which system ground you have? Maybe someone with direct knowledge can correct me if I'm wrong. :-)

Great to hear they will work anyway. What kind of output are you seeing from your 2 panels?

Thanks,

CJ

[Scott Berg]

The expert on this is Bob Williams of S.A.L.T. in Marathon; I'd hire him as a consultant on a project like this… their website has some info… just my 2 cents

[s/v Holiday]

Here is what I have found so far.

From the Sunpower Safety and Installation Instructions from 2011 "Important! For optimal performance, SunPower PV modules must only be used in configurations where the positive polarity of the PV array is connected to ground. Failure to comply with this requirement will reduce the performance of the system and invalidate SunPower’s Limited Power Warranty for PV Modules."

Since they will not warranty installations on boats i Guess that will not matter.

Thanks

CJ

[gspeak]

That was 2011!

[s/v Holiday]

Finally found my answer.

- Previous generation: 2005-2011. These modules required positive grounding. One version:
o Gen 2 Maxeon cells. Module efficiencies up to 18%.
- Current generation: 2011 onward. No positive grounding required. Two versions:
o E series: Gen 2 Maxeon cells. Module efficiencies up to 20%.
o X series: Gen 3 Maxeon cells. Module efficiencies up to 22% and better shade tolerance.

Thanks for the help and suggestions. I will post how the install goes.

Cheers,

CJ

[F51]

Here is the label from one of my X21-345 panels. If you cannot read it, the fine print says" Suitable for ungrounded, positive, or negative DC systems."

I am almost always partially shaded on at least one of my 2 panels. Still, I am getting 160 to 180 amp hours per day in the Florida Keys.