What is the recommended wire specification for connecting solar panels?  The local engineer suggested 10mm instead of 4mm, and I am experiencing really low Amperes from the panels. Could the wires be the cause?

This will depend on the voltage of the array. The distance from inverter and the amps from the panels.

10mm is actually a very thick wire for normal solar systems. Normally one uses 4/6mm wire but as I said it depends.

28 minutes ago, Jacques Ester said:

This will depend on the voltage of the array. The distance from inverter and the amps from the panels.

10mm is actually a very thick wire for normal solar systems. Normally one uses 4/6mm wire but as I said it depends.

Thanks for your response.  The panels have Vmp of 31.6V and Imp of 17.4A.  The distance from the panels to the Inverters is about 10 metres.  But could the use of the 10mm reduce the Amperes by almost a third?  I am getting about 10kWH daily and the expected power from 16 x 550W at this time in Lagos, Nigeria is about 31kWH.

On a distance of 10 meters the voltage drop is minimal, the fact that you only getting 10 KWH out of your system maybe the fact that is all you using, the system will clip whatever is more than your load.

23 minutes ago, Alooma said:

Thanks for your response.  The panels have Vmp of 31.6V and Imp of 17.4A.  The distance from the panels to the Inverters is about 10 metres.  But could the use of the 10mm reduce the Amperes by almost a third?  I am getting about 10kWH daily and the expected power from 16 x 550W at this time in Lagos, Nigeria is about 31kWH.

Slow down there... are the 16 panels all in parallel or in series or how is this lot wired? if they're all in parallel and then you run 10mm^2 cabling 10m to the MPPT/inverter, then the cabling may be a tad too thin... so, how is this lot wired exactly?

I have tried to put loads on the system, but the batteries were used to support the solar power.  The solar power is just not being harvested enough with a maximum of about 2.8A.  The voltage has been good at about 280V.

The 16 panels are connected in series of 8 to each Growatt SPF 5000 ES Inverter.  The two inverters are connected in parallel.

The cables from each series are wired to the Combiner Box and then to the Inverters.

1 hour ago, Alooma said:

I have tried to put loads on the system, but the batteries were used to support the solar power.  The solar power is just not being harvested enough with a maximum of about 2.8A.  The voltage has been good at about 280V.

The 16 panels are connected in series of 8 to each Growatt SPF 5000 ES Inverter.  The two inverters are connected in parallel.

The cables from each series are wired to the Combiner Box and then to the Inverters.

@Alooma It makes no sense to me, I basically have a similar installation, also 2 Growatt's 5000 ES in parallel.  In my case with 6 X 450 W panels in serries on a good sunny day I get +_ 12 Amps on each string.

2.8 amps from your PV seems to be much to low. Something is not right. 

Look at my dashboard, as an example my system was idling and just for you to see I put in +_ 3 KW of load, see how my system reacted. you should see something similar.

Thanks for your response and contributions. I totally agree with you that it does not make sense.  I will have to invest in checking the entire wiring of the panels, it is possible that there is a mistake somewhere and the two inverters are reporting similar Amperes.  And if I can add, there is no shading.

On 2023/02/21 at 12:27 PM, Alooma said:

The panels have Vmp of 31.6V and Imp of 17.4A.

 

On 2023/02/21 at 1:02 PM, Alooma said:

The 16 panels are connected in series of 8 to each Growatt SPF 5000 ES Inverter.  The two inverters are connected in parallel.

The cables from each series are wired to the Combiner Box and then to the Inverters.

ok, the "combiner box" worries me, there should be no combining, if you have 8S going to the one inverter and 8S to the other... and 8 X Vmp or 31.6V = 250-odd V, so if you're seeing 280V, then presumably the inverters are not trying to draw current from the panels, hence the high voltage and very low current... check out the combiner, this should only connect each 8S string to a fuse or trip switch and a surge protection device and the two strings should not interconnect in any way shape or form...

1 hour ago, Kalahari Meerkat said:

 

ok, the "combiner box" worries me, there should be no combining, if you have 8S going to the one inverter and 8S to the other... and 8 X Vmp or 31.6V = 250-odd V, so if you're seeing 280V, then presumably the inverters are not trying to draw current from the panels, hence the high voltage and very low current... check out the combiner, this should only connect each 8S string to a fuse or trip switch and a surge protection device and the two strings should not interconnect in any way shape or form...

Just as you point out I also pointed out to a friend when a 8kW Sunsynk was quoted and the quote contained a combiner box and only 6x380W panel were fitted. This installer went further to use 4 facing NW and 2 NO????

Thanks.  The suppliers in China suggested two inputs and two outputs combiner box.  The spec is attached.  I also notice that the panels are dusty, I am planning to get these cleaned as they are on the roof, and then try to measure each panel's output into the combiner box and out of it.  The issue now is getting the local installer.  Since the two strings give almost the same Amperes, it could be the combiner or even the wiring.  I will update you as I progress.  I do appreciate your help.

 

 

 

All the panels are facing South and the roof is at an angle around 7 degrees.  The photograph of the Combiner Box is attached.

Combiner Box.HEIC

On 2023/02/21 at 12:27 PM, Alooma said:

The panels have Vmp of 31.6V and Imp of 17.4A.

 

40 minutes ago, Alooma said:

The suppliers in China suggested two inputs and two outputs combiner box.

ok, but the combiner with 15A per string is too skraal, since the panels should provide 17.4A and potentially a tad over, you should probably provide for 20A per string, not to have any nuisance fuse popping...

43 minutes ago, Alooma said:

ok 2 fuses, 2 DC Breakers, but only 1 SPD? if that is correct, then this lot is combining the output, I'd imagine... and thus won't work correctly, no 2 MPPTs want to share a bunch of panels... if this is what is happening...

Thanks.  I am are-checking the spec of the Combiner Box.  I think that there are wo SPDs, but will confirm with the installer.

13 hours ago, Alooma said:

Thanks.  I am are-checking the spec of the Combiner Box.  I think that there are wo SPDs, but will confirm with the installer.

the LHS Surge protector seems to be missing its earth connection, which means it will not be doing its work... and you should probably not use HEIC images, not everyone can view them and they certainly don't display in-line on the web page...

Edited February 24, 20233 yr by Kalahari Meerkat

Thanks.  I will check on the earth connection with the installer.  The use of right image files is noted.  I again wish to state that I do appreciate your time and effort in helping to resolve my issues.

UPDATE.

I am yet to get the installer to review the earthing of the SPD.

However, I got someone to get to the roof and shoot the video of the panels.  I found out that they are very dusty - installed about 3 months ago. I wanted to get someone to help clean them with water, but fortunately, it rained last night.  This morning, my Solar Power generation went up to 23kWH for the day, and was able to get the Amperes unto 9A midday fro the previous maximum of 2.3A.

I will continue monitoring and hope that the installer will check the earthing.

Meanwhile, I think that if the panels are properly cleaned, I could get nearer to the expected 31kWH per day at this time of the year.