System Design exceeds Inverter Maximum DC current: No Error Message

Hello Paul,
I have a the following components:

• PV Module: Short circuit current (Isc) = 9.81 A
• Inverter: Maximum DC current = 49.5 Adc

And the following System Design:

• Number of inverters = 20
• Strings in parallel in subarray = 120

Calculating the DC current:

• Total PV: 9.81 A * 120 = 1177 A
• Total Inverter: 49.5 Adc * 20 = 990 Adc
• Results: 990 Adc < 1177 A

Hence, my PV output current exceeds the maximum inverter input DC current. But SAM does not show me any error message. Is this on purpose?

My SAM simulation file is attached.
Best,
Patrick

Hi Patrick,

During the simulation, SAM limits the inverter input voltage to the min and max MPPT voltage ratings and its AC output power to the rated AC output power, but does not check the input current.

You can check the short circuit current of each subarray in the outputs to see if it exceeds the rated limit. For example, on the Statistics tab of the Results page after running a simulation, look at the "Max" value of Subarray 1 String short circuit DC current (A).

Best regards,
Paul.

Thanks, Paul!

I followed your instruction and Subarray 1 String short circuit DC current (A) = 10.8 A

How is this possible when one module hence one string has a Short circuit current (Isc) = 9.81 A ? I assumed that the Subarray 1 String short circuit DC current (A)should never exceeds 9.81 A, but it does?

In my System Design with 120 strings in parallel, this would result in 120 * 10.8 A = 1296 A. This is significantly more than the 20x inverter's max. DC input current of 49.5 Adc per inverter, meaning 20 * 49.5 Adc = 990 Adc < 1296 A. Wouldn't be a warning by SAM useful?

Thank you again for your time! Best, Patrick

Hi Patrick,

The results I get from your file show a maximum short circuit current of 9.307 A, which is less than the module's rated 9.81 A:



Best regards,
Paul.