SAM does report the operating DC string voltage for each subarray and the inverter DC input voltage, which you could compare to the inverter MPPT limits to determine when clipping would occur.
For systems with one subarray, the subarray DC string voltage is the product of the module maximum power point voltage and number of modules per string: The inverter input voltage is equal to the subarray string voltage.
For systems with more than one subarray, when the subarrays have different orientations or tracking options, SAM estimates the inverter's input voltage by averaging each subarray's string voltage. The cell temperature of modules in each subarray will be slighlty different because each subarray is exposed to different incident irradiance levels.
If you use the CEC module model option, you can enable the subarray voltage mismatch calculation option on the System Design page to use a more accurate method to estimate the inverter's input voltage.
Best regards,
Paul.