mnpv6 and surge protector (600)

[nsr13]

Hello all,

This is a first time setup with our combiner box and a new surge protector (image attached).

When wiring it as we think the directions tell us, using the instructions which came with, but which do not show our exact setup, and having three (lg) panels in parallel (there are four breakers but one is a spare and is not hooked uo (the one to the extreme right), and then flipping the breaker up on the first to the left, we get the lights in the protector. when flipping the second to the left, same thing. and with both breakers up, the box still puts out about 37 volts open circuit....as I think should be as this is a parallel installation and the official number for these lg panels, depending on how one measures, is about 40.x open circuit)
HOWEVER, when we flip the third breaker (they are midnite single pole, 20amp breakers), the surge protector lights go out and the box voltage output drops to 4.x volts.
removing the protector entirely enables the box to do exactly what it should...each panel measures about 37 volts and the combined output in this parallel connection is still approx 37 volts, depending on how much sun, time and so on...so without the protector, all appears well.
in the attached photo, the surge protector is mostly unwired, but when it was fully wired to this box, the black wire went to the busbar on the left which carries the negative side of the panels, the red wire goes to the top right screw on the panel to which the breakers are attached and the green wire goes where you see it, which is the ground busbar on the right as you face the box.
what, please, are we doing incorrectly, if anything?
many thanks...we are novices and appreciate the help!

[aaapilot]

What happens to the surge protector when you just turn on the 3rd CB without the other two? 

As a separate observation, your subject line implies you used a 600v Surge Protector for a 37v system?  Midnite makes 125V and 300V DC Surge Protectors to more closely match the voltage of your system.  Perhaps a more knowledgable member can comment on whether this great a difference affects the operation.

Dave

[nsr13]

thank you kindly.

what happens when just invoking the third, is "nothing". no lights.

as to the capability of the protector, when speaking with stellavolta, who distributes so much of midnite's product (and who gave me great service), it seemed certain that nothing was to be lost by buying the biggest one...and insofar as I am one who likes redundancy and "headroom", so to say....I might have a different configuration in future and can use this.................and provided that the largest one is the most readily available (go, for example, to amazon, and that is the one that pops up), my thinking was that unless I am missing something, and provided that I could have paid a modest amount of money less for a lesser version, getting this one was the best value for me.

thanks again for your response.

[nsr13]

ps pse allow me to repeat, that with this unit off line, as it is now per the photo, that everything else works perfectly.

so it would seem that either the choice of how to wire it in was fine for what was in the instructions, but not for my simply set up here or this one is defective. I cannot think of a third possibility

[Wizbandit]

Your breaker #3 has a PV NEGATIVE wire connected.  Check polarity of the two wires, you may have them reversed.  That is the #1 cause of what you are experiencing... Or PV Module#3 is defective or the wiring has an issue...

[nsr13]

thank you very much

PV 3 works perfectly when the protector is out of the loop. it all does.

my ignorant guess is that this is a wiring issue (of the surge protector, itself) as we tried what LOOKED LIKE the right way to do this, but it was an extrapolation, as I could find nothing that idiotproofed it for me when using exactly what I have here....so my intention is to ask stellavolta tomorrow.

but they are selling all this and if there were some kind of common malfunction due to the item itself, I would assume they would know that and say "send it back"...so I will swallow hard and wait until tomorrow, since this one issue is all that is standing between me and a whole new operational system which I have been working on for a long, long time (I am not a well person....including recent lung cancer surgery, so the progress has been mitigated by finding others to help me while being in a semi-regional area....but in any event, I am excited to get on with it :-) )

[Wizbandit]

Where does that black wire you have on your ground bar in the combiner box go?  I hope it goes to a ground rod or ground lug on the inverter and not to battery negative.  Good wiring practices use a green colored wire or bare copper for all ground and grounding circuits.

[nsr13]

thank you.

it goes to a chassis ground (this is in an RV) and not to battery negative.

[nsr13]

also, a comment was made here, and I just realized it, that a pv negative wire was connected to the third breaker, but respectfully, while I did not connect the wires, myself, I do not believe this to be the case.

may I please know why you think this?

thank you.

PS yes, the wire is dark gray, but due to what we had available in large quantity at the time of the installation of the panels, we had a lot of great wire...but all gray...so we color coded it at the time of install and i remain highly confident that what is connected to the breaker is, indeed, a positive. *in*deed, with the protector out of the wiring, and putting a VOM meter for DC on the positive of each of the three breakers, while using the busbar on the left (as you face the box) where all the negative sides of the three breakers are hooked up, and each breaker shows a positive voltage.
then, with all three breakers on, and measuring the voltage coming off of the combiner box itself...which wired in parallel, should, I believe, give us the same voltage measurement that we see on each of the three panels (each panel measures a tiny difference in voltage as they are not exactly in the same spot, etc.....but if the voltages on each are approx 37 volts, and the combined array in parallel gives us that same voltage within a few tenths, anyway, I continue to assume that this is working as it should)...............AND that if there were any polarity issues, we would see it when measuring each panel at the breaker as described above and as well, we would get a weird reading from the output of the box, as well.
if anyone disagrees with this, of course, please tell me!
thank you all.

[Brucey]

Can you try moving the connected strings around to see if the problematic breaker moves with them?