Inverter Isc DC Input Ratings
Inverter short circuit current (Isc) rating is required to verify that the PV module string short circuit current under high irradiance does not exceed the maximum input current for the PV inverter's MPPT for compliance with NEC 690.8(A)(1)(1) and the inverter listing. Inverter Isc might not be reported consistently across manufacturers, if you are having trouble finding the required information on your equipment or interpreting manufacturer documentation please refer to the following examples:
The Sunny Boy inverters have a maximum short circuit current of 18 A and “Maximum DC Voltage” of 600 V:
The Delta Mario inverters have a “Maximum System Voltage” of 600 V and max MPPT current of 15 A M4 to M8 and 25 A for the M10:
The Tesla inverter has a max MPPT current of 15 A and a maximum input voltage of 600 V:
The Fronius inverters have a maximum short circuit current of 18 A and a maximum input voltage of 800 V
Delta E6 has a “DC Max System Voltage” of 480 V and a "Maximum input current per MPPT" of 12 A which makes the maximum input short circuit current of 12*1.25 = 15 A
For Enphase systems, the contractor may find this Enphase website helpful. First, you can enter the module brand and model number to determine eligibility with Enphase products. This tool will also show the Max Isc, based on your temperature inputs and equipment. An example, is shown below.
The contractor can then enter the DC input voltage and current within SolarAPP+. In this case Max Isc is 15 A and the contractor would enter 15 A for the maximum input DC short circuit current (Isc).