DinoV

Hi all. Finally had some more time to tinker with my system and solve the problem. I installed a new 6mm solar DC cable and pulled out the old 4mm cable and connectors. When I opened the old male and female connectors I noted that the cable pulled out of the connectors VERY easily. On opening I noted that the cable had not been well crimped all those years ago. New cable + new connectors + good crimping means that I now have almost perfect voltage at my invertor (166V) with full sun. Today it is mostly cloudy and I am getting 135V at the invertor. Thank you everyone for your kind input. I think we can close this topic as "solved".

Greetings all. Just a quick reply to relate that I have been busy with other prioritites over the last 2 weeks and haven't done anything further about this situation. I have purchased 6mm solar dc cable (hopefully copper) and will look at changing my 4mm cable for the 6mm cable. The surge arrestor is still disconnected. I don't know how to test it. It's just one of those that has a green indicator that turns red once the arrestor has "burnt out". At present the indicator is still green.

measured all 4 panels in series = 167V at 10am (partly cloudy today) at the combiner box I disconnected the surge arrestor and had 147V at the breaker. The inverter had a reading of 117V I have left eh surge arrestor disconnected and had a mostly consistent 110V at the invertor even in complete shade.

@Kilowatt Power yup the multimeter is pretty clear. Measuring Volts definitely.

I can't definitively say that I noted polarity of each panel. I was very methodical when installing by using the manufacturers labels, so that each panel "faces up" so to speak. So the labels of each panels are on the top high end. When I looked at polarity when finally connecting them together, the poles per panel are labelled as "+" and "-". The male and female connectors are identical across all panels and the "+" with a male connector joined perfectly to the "-" female of the next panel the whole way across. There were no hiccups in that regard. Then when I tested voltage per panel, earlier this week, the leads of my multi-meter were used identically across panels - red lead to my right connecting with "+" and the black lead to my left connecting to the "-". I did this identically across all panels and all readings were in a positive range. I did not experience any negative readings during that process which may indicate reversed poles (I think). If there are reversed poles I haven't experienced anything directly related to each panel that has given me an indication that there might be a problem. Out of interest, I opened the "+" terminal on one panel (it's a little black pop out and clip in cover) over the terminal and can report that on that one panel the manufacturer has completely sealed any access to wiring, terminals etc on the inside of the panel. It's sealed in white resin or epoxy or silicon of some sorts.

Thanks @Coulomb. Unless there is some unknown definition of "under load", I'm pretty certain that I'm measuring without it being under load. I measured the panels directly while being disconnected. I think this means that it's not under load. Then at the junction box (approx 8m away from neutral of the PV series), before connecting to the breaker (breaker off, which again I think means no loads) I measured again. So each panel was in the range of 42V - 44V and then open circuit reading at the junction box was 80V (no load). The inverter itself gave a slightly higher reading (89V) than my multimeter when everything was connected, switched on and under load. I do agree, that at present, adding extra panels doesn't seem to be the solution. If the panels themselves are high resistance what would be the solution? @TaliaB I was wondering about measuring current. So I will add this to my list of "things to measure" on Saturday. Thank you so much.

Thanks @TaliaB I'm leaning towards a resistance problem on the cable. I will still try find a way of testing the total string of panels (they seemed fine individually when i measured them earlier). It's a straight run from the panels to my breaker. There is only 1 x male and 1 x female connectors besides the cable - nothing else inline. I found that voltage drop calculator earlier, after taking the measurements I posted above and noting the massive voltage drop, which also seems to point to the cables being a problem. It is an older cable that was already here previously connecting a smaller 280W panel. I removed the panel but didn't change the cable. So it could be that there is an unseen break in the cable. I'll tinker more on Saturday and see if I can test resistance across the cable. I'll be happier if it's a cable fault as it will be cheaper than buying extra PV panels.

I was also wondering about that. The problem is that the "+" of the first panel is 4m away from the "-" of the last panel. My little multi-meter can't stretch that far.

So I measured each panel this morning at 10:30am. Each one seems fine with the results ranging between 42V and 44V (It's partly cloudy today, mostly cloudy). Back at the breaker (8m cable length to the neutral end of the PV series and 4m to the Live end of the series) the voltage measured 80V. The only thing between the DC circuit breaker and the panels is cabling. If I understand this correctly, I should be getting ±160V across the panels but am only receiving 80V after the cable run to the breaker. That's a 50% drop in voltage over the distance. I'm not an electrician but this does seem extreme with my limited understanding. The other thing that confuses me a little is that it is cloudy today and I appear to have a higher voltage reading compared to the 65V I had yesterday which was perfectly cloudless.

I have a clear sky scenario here until 2pm during Winter - not factoring in clouds of course. However since starting this post, there hasn't been a cloud in sight for 2-3 days. (clear, clear, clear). I have received some input from the panels since connecting last week. It just seems very limited. I just checked the display and it said 5.5kWh. Not sure if that's today only OR since connecting (i.e. total historical production). Also, while cycling through the display, I note that the inverter also offers a voltage reading for the PV input - currently 71V at 1:46pm

Thanks good to know. Alas, the panels are all in series - positive of one to the negative of the next - all the way through. EDIT I'll make time to take more readings on my multimeter before purchasing the two extra panels. I'm certainly not keen on spending more at this stage plus the next sub-structure installation will be more difficult than the current one, so it will be a bit of a headache to add more panels.

For sure - isolator in place. Very little shading until after 2pm (Winter months) 4mm cable currently used

Thanks everyone. When I have a free moment, I'll climb up to the panels themselves and measure the VOC directly. The VOC of 65V was double checked this morning (between 10-11am, at the inverter) and confirmed. I don't have ideal orientation on my panels (closer to NE) and there is about 8m - 10m of cabling from the inverter to the panel array. So I suspect I'm experiencing more voltage loss due to those. Out of interest, let's say that 65V (55% loss) is ridiculous. What sort of inefficiency should I be expecting from poor orientation and voltage loss over distance?

Thank you kindly for your reply. The input voltage range is 120V - 450V with a max open circuit of 500V. I have 4 panels connected in series. The nominal voltage per panel is 35.93V. I have a circuit breaker inline between the panels and the inverter (about 1m away from the inverter, so it should cover most of the voltage drop due to cable length) where I measured about 65V yesterday, around the middle of the day. So I suspect that it is a voltage problem and I will need to add more panels to increase the voltage to the inverter. Unless there is some other unforeseen element that I'm missing.

Good day I have a Kodak OG5.48 off-grid inverter. I have been running it with a Hubble AM2 (5kW) lithium battery, as a power backup system. I finally had 4 x 500W Art Solar panels connected last week and have been trying to run with A Solar / Battery / Utility priority order. I noted that the inverter does not regularly accept the solar power coming in and the MPPT controller icon just flashes on the LCD display. I cannot find this scenario in the manual and therefore am not sure how to troubleshoot.