Dear Francisco,
Of SAM's CSP models, we have only tested the Physical Trough model with subhourly simulations. Because the models were designed to run hourly simulations, they may not accurately model thermal transient effects at shorter time steps.
Simulations for the other CSP models may run at subhourly time steps, but the results are reported in hourly timesteps and can be misleading.
We are tracking this issue in the GitHub.com repository. Please see the description there and in the support forum conversations linked from that desciption:
github.com/NREL/ssc/issues/2
Best regards,
Paul.