1 MPPT with 2 string of modules

[elisdown]

Hi,

 

Some of the market inverter is available of 2 strings per MPPT but there is always a warning in the software "You should define at least one string per inverter or MPPT Input".

 

What should I do if I am going to do the following layout?

- Sub-array # 1 : 1 MPPT with 2 string of 15 modules

- Sub-array # 2 : 1 MPPT with 2 string of 16 modules

- Sub-array # 3 : 1 MPPT with 2 string of 16 modules

[elisdown]

1 hour ago, elisdown said:

Hi,

 

Some of the market inverter is available of 2 strings per MPPT but there is always a warning in the software "You should define at least one string per inverter or MPPT Input".

 

What should I do if I am going to do the following layout?

- Sub-array # 1 : 1 MPPT with 2 string of 15 modules

- Sub-array # 2 : 1 MPPT with 2 string of 16 modules

- Sub-array # 3 : 1 MPPT with 2 string of 16 modules

FYR. I am using the Sunny Tripower CORE2 which has 12 independent MPPT and 2 strings per MPPT.

https://files.sma.de/downloads/STP110-60-AFCI-DS-en-20.pdf

 

Should I create an inverter config and set mannually to 3 MPPT? And the Max PV Current becomes 120A (40A Isc x 3 MPPT)?

[Muhammed Sarikaya]

Dear Elisdown,

You have to contact SMA if your modification will take into account the power sharing between each MPPT.

If you want to connect only 3 MPPTs out of 12 MPPTs, PVsyst will not allow it.

In reality, you should contact SMA to inquire whether it's possible to configure only 3 MPPTs and if it's allowed.

Regards,

Muhammed Sarikaya

[André Mermoud]

Just a remark concerning  your doubt about the warning   "You should define at least one string per inverter or MPPT Input".

This corresponds to the SubArray you are just defining: if you define N MPPT, you should obviously define at least N strings, i.e. at least one string per MPPT defined within this subarray.

 

[shubham22sharma]

Quote

Let's suppose, I am using a growatt 50 kW inverter, that has 6 mppts. In practical the site team has used only 4 mppts out of 6, than how can I simulate this in pvsyts? 

[Linda Thoren]

If the strings have the same lengths, it is sufficient to just untick the Use multi-MPPT feature and define the total number of strings to the inverter. 

If the strings have different lengths indeed you you will have this constraint in the current version that you can not have empty MPPT inputs. To get around the constraints in PVsyst, you could modify the OND file to 4 MPPTs instead of 6, though by default, PVsyst assumes that an inverter with e.g. 2 MPPT inputs behaves as 2 identical inverters of half the power. You thus might have to adjust other parameters too to correspond to the use-case you are referring too. In the following help page you find more information of how PVsyst defines multi_MPPT inverters:
https://www.pvsyst.com/help/multi_mppt_use.htm