Problems with Series/ Parallel strings not adding ampage.

[yoz7241]

Hi Guys, im hoping someone can help me.
I have recently installed 3.2kw system for an offgrid job. The problem im getting is that im only ever seeing around 300 watts solar generation for the whole system.

We have used 10 x Canadian Solar 320 watt panels Voc for the panel is 44.9 and the ISC IS 9.08A also the short circuit current is 9.26
I have used Victron energy for my solar charger (150 volts/ 70 amp along with bi directional inverter.
I have had to wire them as 2 in series/ 2 in parallel for one mppt and 2 in series/ 3 in parallel for the other mppt to meet the solar chargers perimeters.
the actual voltage i am now getting is 87 volts at 8 amps per pair, but when i add them all together it stays the same (87 volts at 8 amps) the ampage does not add.

I have tested every panel individually and the voltage and ampage per panel is correct but them i carried out a short circuit current test and my highest reading was 1.34 amps out of the 10 panels.

I have triple checked the wiring and its not that, i have also had Victron take a look at the solar charger and even replaced it for a new one but also it was not that.

Its also not because the battery bank is fully charged either because its not.

Its not the weather either as it was a belter of a day but still the same.

Is it possible i have 10 x bad panels? Its never happened to me before but theres always a first.

I am scratching my head on this and have been back and forth for the last two weeks.

Any help on this and i would truly appreciate it.

 

[Gavin A]

you've probably wired several of the strings in reverse polarity.

The answer to these types of questions is usually reverse polarity, I'd triple check that before doing anything else.

I know it sounds basic, but it happens to the best of us, so it's always the first thing I triple check even when I wired it, or whoever else wired it swears blind that it was done right 90% of the time that's what it is.

 

[yoz7241]

you've probably wired several of the strings in reverse polarity.

The answer to these types of questions is usually reverse polarity, I'd triple check that before doing anything else.

I know it sounds basic, but it happens to the best of us, so it's always the first thing I triple check even when I wired it, or whoever else wired it swears blind that it was done right 90% of the time that's what it is.

Its not reverse polarity either, our solar charger wouldnt work if that was the case. Plus i checked that first.

 

[Wilko]

Hi - just reading the thread - if it isn't wiring, then : do these panels come with individual test sheets? I'd get the light meter out to confirm what current you should get and contact the manufacturer for advice.

 

[Gavin A]

if it's dual MPPT inverter then it may well work on one side, and if you've got 2 strings the right way round, 1 the wrong way around then this would end up with it looking to the inverter as if it's got a single positive string.

I've heard too many electricians tell me it's definitely not reverse polarity I've checked, then be proved wrong - that's still what I'd put my money on.

Chances of it being the panels are miniscule.