Inverter unbalanced load

[spionkop]

When trying to match an inverter to a PV array I come across figures for 'Unbalanced Load'.
What causes an unbalanced load and how critical is this.

 

[Markc]

Different number of panels on each string. For example a 11 panel system on two strings. I have always avoided unbalanced and reverted to a different inverter.

 

[robbobnbill]

the other way around it is to use 2 smaller inverters

 

[spionkop]

Thanks for that guys. I can see that strings with different numbers or sizes can give an unbalanced load but when I put eg. three strings of equal size capacity and manufacture into my software it shows an unbalanced load of 3.3kVA and I just wondered how this could be and if it is acceptable?

 

[Markc]

Thanks for that guys. I can see that strings with different numbers or sizes can give an unbalanced load but when I put eg. three strings of equal size capacity and manufacture into my software it shows an unbalanced load of 3.3kVA and I just wondered how this could be and if it is acceptable?

I have know manufactures software to allow three strings but their inverter only has two? What is it you are using and on what panels & inverter. I can run it through PV-sol if you give the details. Number of, make and model of panels and inverter make and model? I wouldn't do your design just see what it throws out.

 

[spionkop]

Hi MarkC.
I am planning a 6.6kWp array using Kyocera KD185GH-2PU panels which conveniently split into three strings of 12 panels, through a Fronius IG Plus 70-2 inverter.
Look forward to your findings.

 

[dansk]

You can also do 2 x strings of 18.

 

[Markc]

Hi MarkC.
I am planning a 6.6kWp array using Kyocera KD185GH-2PU panels which conveniently split into three strings of 12 panels, through a Fronius IG Plus 70-2 inverter.
Look forward to your findings.

Hi Spinokop

18 Panels on 2 Strings produce a better result on the same inverter. See pic's

 

[spionkop]

Thank you Markc. I see what you mean so I will go with 2 strings. Apologies for the delay in replying, I have been away.

 

[Markc]

Thank you Markc. I see what you mean so I will go with 2 strings. Apologies for the delay in replying, I have been away.

No problem glad to help. Let us know how you get on and Pictures are always welcome.