2 Orientations: Strings vs. MPPTs vs. Pnom ratio vs. Power Sharing

[Carlos Melim]

Good morning, everybody.

 

I have a PV System with 100 un  550W modules but with two orientations:

• 1 string with 20 modules, orientation 1 (20 modules)
• 4 strings with 20 modules, orientation 2 (80 modules)

The 5 strings are divided in three arrays:

Sub-array 2 with orientation 1:

PV Array and Sub-array 1 with orientation 2:

 For I have two orientations, I want to use the multi-MPPT and Power Sharing features.

I have 5 strings but I can find only 4 or 6 MPPTs inverters.

Assuming I choose a 40 kW 4 MPPTs inverter:

• If I connect the 5 strings to 3 MPPTs inputs the Power Sharing feature will not work. The inverter MPPT inputs are not complete.
• If I connect the 5 strings to 4 MPPTs inputs the Power Sharing feature will not work. The inverter doesn´t have enough MPPT inputs.

Assuming I choose a 60 kW 6 MPPTs inverter:

• If I connect the 5 strings to 5 MPPTs inputs the Power Sharing feature will not work. The inverter MPPT inputs are not complete.
• If I arrange the the 80 modules orientation 2, in 5 strings to complete the 6 inverter MPPT inputs, Pnom ratio will be too low.   

 

What am I  missing?

 

Any help will be greatly appreciated.

I am looking forward to hearing from you.

Best regards

 

Carlos Melim

 

Edited September 5 by Carlos Melim

[Muhammed Sarikaya]

Dear Carlos,

 

I can't see the step where you define the power sharing, so I assume that you have mastered the subject.

I can suggest the following steps for the 40 kW inverter with 4 MPPTs:

1. First inverter input: connect 2 strings
2. Second inverter input: connect 1 string
3. Third inverter input: connect 1 string
4. Fourth inverter input: connect 1 string

This requires you to create 4 sub-arrays where you define the previous inputs. That means you will have:

• Sub-array 1: 2 strings
• Sub-array 2: 1 string
• Sub-array 3: 1 string
• Sub-array 4: 1 string

This method will allow you to create and use power sharing effectively.

If you need more help, don't hesitate to reach out to us.

 

Regards,

Muhammed Sarikaya