Error in System Parameter When Using a Y-Connector for Parallel Strings

[Shibin Paulose]

Hello,

I am planning to use a Y-connector wherein I will be combing two strings in parallel using this and then connecting the string to the inverter input. So effectively in one input I shall be connecting two strings in parallel. This is a standard practice. But I face a problem when I try to put in these as my system parameter in PVsyst.

I am using a 100kW inverter with 9 MPPTs (Sungrow SG110CX) and 355Wp modules. My string configurations are as follows: MPPT 1: 19*3 (two strings are connected using Y-connector), MPPT 2: 18*3 (two strings are connected using Y-connector), MPPT 3, 4 & 5: 20*2 each, MPPT 6: 20*1, MPPT 7: 19*2, MPPT 8: 19*1, MPPT 9: 20*1.

When I try to assign 3 strings into one MPPT input (for MPPT 1 & 2), PVsyst shows an error saying the inverter is strongly undersized since the Pnom ratio becomes 1.72.

I am attaching a screenshot for reference. Please suggest a way to circumvent this problem to simulate the system parameters.

Thanks in advance!

[André Mermoud]

You should use the "Power sharing" option for distributing the available Nominal power ont several MPPT inputs.