Best suggestion is to verify with the Utility Service Engineer / Planner, as to what data is satisfactory for the SCA submittal; i.e. Manufacturer's Cut-Sheets, or Actual Field Test.
The Service Planner should tell you specifically where to obtain the Data (Mfg. or Field Test), along with submitting relevant ESR Pages to you, for reference.
Contact the Service Planner, and verify where the SCA Data is to be derived - Spec. Sheets, or Field.
If a Field Test is required (sounds unlikely, but....), then you will need to perform the Test as indicated in the ESR Manual (Electrical Service Requirements), as well as per the MFG. Specifications.
Typically, such a Test involves connecting the entire Array together (as would be for normal running conditions), "Bolt" the Output together via an adequately sized jumper, then measure the Current Flow through that Jumper - either via a Clamp-Type Ammeter, via a CT piped into a Multimeter, or via a Series-Type Ammeter (most likely a Shunted Approach).
Testing would be performed with the Sun at the most effective angle (time of day -vs- latitude).