Classic compatible with Sunpower A-300 panels?

[Gianni]

Hello, I'm asking this question for a potential customer who is looking to install the Sunpower A-300 panels in a marine envirolment where space is at a premium.  These panels need the cell positive output to be grounded.  He says that this requires a power point tracker regulator that is galvanically isolated with a transformer in the design.
Can anyone tell me if the Classic is suitable for this application.  Many thanks!

[boB]

Hello, I'm asking this question for a potential customer who is looking to install the Sunpower A-300 panels in a marine envirolment where space is at a premium.  These panels need the cell positive output to be grounded.  He says that this requires a power point tracker regulator that is galvanically isolated with a transformer in the design.
Can anyone tell me if the Classic is suitable for this application.  Many thanks!

Gianni,  Can you get some information about this particular module in regards to grounding ?  I have tried to ask Sunpower questions about this for many years now, and can not get a "positive" answer about the grounding....  I even went to their booth at Solar Power International shows but nobody in the booth knew anything about how to use their modules.  Evidently, one can not talk with an engineer there.
They do have a paper on their site that talks briefly about positive grounding of their modules and that it helps with efficiency, but it leaves way too many questions un-answered.  For instance, can one take a Faraday shield  and place it behind the modules and then ground that ?  If not, then these modules would have no use in either airplanes, space, or anywhere there is NOT a ground handy.  Just too many questions.

What I have heard through the grapevine is that positive grounding id not necessary unless the string voltage is above a couple hundred volts as it would be with a high voltage string inverter application.  This has to do with the high efficiency.

You CAN actually ground the positive leg of the PV array on a Classic  BUT if you do this, you can NOT ground either the battery positive or negative leads, which you would normally need to do.

Thanks,
boB

[Halfcrazy]

What I have heard through the grapevine is that positive grounding id not necessary unless the string voltage is above a couple hundred volts as it would be with a high voltage string inverter application.  This has to do with the high efficiency.

You CAN actually ground the positive leg of the PV array on a Classic  BUT if you do this, you can NOT ground either the battery positive or negative leads, which you would normally need to do.

Thanks,
boB

I have actually heard the same rumor on the Positive grounding and voltage of the string.

Also if the PV positive is grounded much care needs to be taken not to hook anything up to the battery that would ground the DC negative (IE a Ham radio wired to a 12 volt battery with the feed line grounded)

[Gianni]

My slightly non-technical understanding is that for some reason electrons build up on the front surface of the module due to the cells not having grid lines on the front. This build-up affects the performance of the module......but is reversible by grounding the positive leg of the array. Initial documents we read stated that it was not really necessary to ground the positive of a single module installation......but was necessary with an array of modules.

The Classic 150 Manual states:

"The System's DC Negative conductor must not be bonded to earth ground. The Classic does this with its internal Ground Fault Protection circuitry. The battery negative and ground are not bonded together directly but are connected together by the Classic's internal GFP device. All negative conductor connections must be kept separate from the grounding conductor connections. The equipment ground terminal inside the Classic must be connected to Earth Ground for the internal DC-GFP to work. Continue
• With the exception of certain telecom applications, the Charge Controller should never be positive grounded."

I guess my question is:  Do we require a specific model for use in a positive grounded scenario such as a "telecom application"?

[laszlo]

So this thread is kind of intriguing since what I understood was that electrons don't move, only the holes. So it would be hard for them to pile up on the back side of the panel. So, like Bob says, do share what you learned about these modules from their docs. 

I would experiment with either negative or positive grounding of the module, and see if there is a performance difference but to me this sounds like a bit of a snake oil.

My slightly non-technical understanding is that for some reason electrons build up on the front surface of the module due to the cells not having grid lines on the front. This build-up affects the performance of the module......but is reversible by grounding the positive leg of the array. Initial documents we read stated that it was not really necessary to ground the positive of a single module installation......but was necessary with an array of modules.

[niel]

i think the best way to answer some of these questions might be to actually obtain some of their pvs and try it. from what i understand of them is that you can't get them except through sunpower dealers and they aren't supposed to sell just the pvs.