Hi Sha,
The snow loss percentage shown on the loss diagram is the annual loss in year 1 as a percentage of the nominal DC electricity in kWh, which is also shown on the diagram.
You can also display these values on the Data Tables tab by searching for "Annual DC energy nominal" and "DC snow loss". The time series output "DC power loss due to snow" is the snow loss calculated in each time step.
Best regards,
Paul.