XWMPPT 60-150 strange issues

hermit · August 2015

Story, have XW4024 and XW60-150 hooked up running separately Xanbus not hooked up. Works good CC charging as designed. Ordered a second XW60-150 and an SCP to tie the system together. When I hook up the second charge controller it reads no input but has 500w output and 26.5v. After about 5 mins the CC will have input numbers but they make no sense, the output watts are 30% higher than the input watts and the input volts drop off from 90v down to 50v. I tried resetting the CC and it does the same thing. When I added the second CC and brought the system up I had to reset the first CC because it would only charge at 100w. This is still with no Xanbus. The panels are cs6p200p 3 in series 2 strings to each CC. I wired all 4 strings to 1 combiner, each PV+ to its own breaker, all PV- to common bus, in combiner I have separated the PV+ breaker outs into 2, from the CC I ran 4 conductor plus ground to Midnight MNE250XW. All PV- ties together on 1 bus, on the PV+ side 1 went to PV+ bus, to breaker to CC. The other PV+ went directly to a breaker then to CC. (the MNE250XW doesn't have hook ups for 2 CC) The PV- are tied together at the combiner and the MNE250XW panel, is this a no-no? I hooked up the XW60-150 to the SCP but would not power up, tried the other CC still no power, I hooked up to the XW4024 and the SCP powered up. Should there be power for the SCP from the CC? I never hooked up the Xanbus to all devices because I didn't have the cables. If a person fries the diodes in the panels would you get any power out, or would it be lower? I`m asking because even though I put blankets over the panels before I opened the breakers I forgot once when I was rearranging the PV- in the MNE panel and I accidentally touched the PV- off 1 set of PV strings to the PV+ bus and had a small arc (the CC were off and so was the inverter) Another one of many questions when you reset the CC with the panels hooked up is it not the same as opening the PV breakers without blocking the sun first? Thanks for every ones patience.

Vic · August 2015

Hi hermit,

I am not an expert on XW systems ...

So, each CC MUST have its own PV array ...

And in the XW SCC Manual, on page 2-15, Connecting Multiple (SCC) Units, it shows that each PV array has a separate cable run for the PV Plus, AND the PV Negative from each array, and it notes that the PV Neg cable must go to the SAME CC that the PV Pos from THAT array goes to -- PV array #1 Pos AND Neg Must go to CC #1, and PV array #2 Pos and Neg must only go to CC #2. The wiring diagram shows the correct way, and the incorrect way.

Looks like you need to run separate PV negs, one for each array, and to the same CC as the PV Pos from that PV array.

The SCC measures current in the negative lead/s, and the PV Neg can only connect to the PV Neg terminal in the CC associated with that PV array.

If you are using a single Combiner for both PV arrays, you may need to add an optional second PV Negative Busbar. Some Combiners allow separation of the PV Positive busbars into two isolated busses, each with its own connection for the PV Positive output, but, some only have a single PV Neg bussbar, but have mounting provisions for the second PV Neg bussbar.

EDIT: What brand and model number PV Combiner are you using?

Re-read your post again ... and again ... According to the XW SCC Manual, your should NOT connect the PV Neg from either PV array to any neg bussbar in the MNE250XW. These PV Neg leads should connect directly to the PV Neg terminal in the correct XW SCC ie, do NOT cross the Neg from one PV array, PV Pos and Neg from one array must go the same SCC<.

EDIT2: If you are using the MNPV6 Combiner, it has no provision for the second PV Neg buss. You could mount a second insulated buss in the bottom, but it would lack the insulating sheet, if this is the Combiner that you used. This might not pass an Inspection, if that is necessary ...
Here is a MidNite busbar that could work:
http://www.solar-electric.com/installation-parts-and-equipment/midnite/brbusbatebus/mntb.html
<.

The MNPV12 includes the second busbar:
http://www.midnitesolar.com/productP...tOrder=7&act=p

<
If this is clear enough. Good Luck Vic

hermit · August 2015

Thanks for your time and input. Yes I am using an MNPV6. I will have to go over installation instructions for hooking up devices as I recall the picture for incorrectly hooking up the PV`s showed not to cross the PV- from one array to the next going to the charge controllers. It never stated not to hook the PV- common or at least I dont remember reading that statement. The array system is being used in a recreational week end setting. On the MNE250 there are PV- and PV+ bussbars dedicated for PV input meant for only 1 CC hookup.I`m not hooking the PV- to ground or neutrals or Battery-. On 1 of the CC I removed the PVGF fuse as per manufacturer. I also exhibited the same CC results when the other CC breakers were open for PV+ in and Battery+ out. The CC are set identically. There were never any faults on either CC. I didnt have the manuals on hand as the property was 1.5 hrs from my residence (yes I should have had them there for reference) I am going to seperate the PV- in the system going to the CC next time I`m out there. I disconnected the second CC and am back to using the orignal CC and all is well. I would have disconnected the first CC and tried using the second new CC but I ran out of time. Again thanks for your input.

Vic · August 2015

Hi hermit,

The Wiring Diagram in the XW SCC Manual is incomplete, as is the description ... seems that this Manual borders upon being threadbare. But, Schneider seems like a tightwad company, and every page that is not in their manuals is another penny (or less) that they can save. This chintzy-ness could well cause users to make more calls to Tech Support, and this costs them, big-time.

From your description of the site, it seems that there will be no required inspections (assuming).

To your application;
First, seems to me that you must use separate Negative busbars in the Combiner, for each of the two PV array. You can find a convenient place for this buss in the Combiner. Again it is unlikely that this added Neg buss would pass an inspection, but should still be safe. It might be difficult to find the insulator that mounts (normally) under the insulated busbar... Previously, Outback offered a busbar option for their PSPV12 that included the insulating sheet, but believe that now, the PSPV12 includes the second PV Neg busbar ... A Code-correct combiner that includes the second PV Neg buss would be the MNPV12, but, that is a much more than you need, save for the added PV buss.

Next, if should be OK to continue the PV Neg buss in the e-panel, as long as there is only one PV array's negative cable on that buss. That is, the PV neg lands on that buss, and then the PV Neg from only one CC is also connected to that buss. AND, there should be NO OTHER cables on this buss.

The PV Neg from the Combiner for the second PV array should run from the new PV Neg buss directly to the second SCC, with NO other connections.

These are just my opinions, as a non-expert on the Schneider XW system components.

Good Luck, and please let us know how you are doing on this SCC behavioral issue. Thanks, Vic

zoneblue · August 2015

Im not quite following what youve got there. But how about one combiner and home run per array, and dont use the disco PV bus, but wire direct to two seperate PV breakers. Not sure what you gain by trying to minimize extra gear with the extra CC, except a muddle.

Vic · August 2015

And, hermit,

Just to make sure;

In the MNPV6, you did cut the busbar into two segments, right? Each MPPT CC must have its own separate PV array:

http://www.midnitesolar.com/pdfs/MNPV2-3-4-6_manual.pdf

Thanks, Vic

hermit · September 2015

Bluezone, I`m not using the disco, all PV+ have breakers on every series string in combiner and have separate breakers for each CC Pv+ in the MNE250. None of the separate CC PV+ are tied together anywhere and have separate breakers. Sometimes its not a matter of minimizing but what I have at the time and still get things done safely. I may get some things wrong but that's a lack of knowledge not trying to be cheap. I would have to travel 6hr round trip to pick up another combiner which I will do next time I`m in the city and sometimes they may not have it in stock at the time.
Vic, yes I separated the bus bar into 2 on the combiners PV+ side of breakers, only the PV- were tied together on the common bus.
Thanks again for the reply`s.

Vic · September 2015

hermit wrote: »

....

Vic, yes I separated the bus bar into 2 on the combiners PV+ side of breakers, only the PV- were tied together on the common bus.
Thanks again for the reply`s.

OK, thanks hermit,

Did not want to beat you up on this, just trying to make sure that each CC had its own separate PV array.

Thanks for the reply, Vic

BB. · September 2015

hermit wrote: »

Vic, yes I separated the bus bar into 2 on the combiners PV+ side of breakers, only the PV- were tied together on the common bus.
Thanks again for the reply`s.

I may be getting lost here--But as I recall the Xantrex 150 MPPT controller--You must have the PV- side isolated too (PV+ and PV- must go to each dedicated controller).

The XW 150 MPPT measures the array current in the negative PV- lead. Do not combine the PV- buses anywhere or it will confuse the paralleled MPPT controllers.

Other controllers (such as the Outback family) do not care if the PV- of multiple arrays are tied together, or even go directly back to the battery and bypass the Outback controllers.

-Bill

XWMPPT 60-150 strange issues

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