Annual Degradation Schedule mode error

I seem to have hit a bug in the software. I am running a Detailed PV model, PPA, single owner.

I would like to input a Annual Degradation Schedule (rather than a value) and no matter what values I enter in the table (including 0, 1, 100 for each year) I always get the message :
Degradation calculated to be greater than 100%, capped at 100%.
and my simulation provides zero energy after the first year.

A few follow up questions:
- I am not sure if I am supposed to be using % or fractions, but any number fails.
- My PV panel loses 2% in the first year, then 0.25 in all other years.  Is there a better way to capture this 2% initial loss. First year value must be zero, but I have to put in the second year.

Hi Andrew,

Yes, that's a bug, and unfortunately there is not a good workaround solution except to use a single value for degradation instead of an annual schedule.

We will fix this for the second update to SAM 2021.12.02.

github.com/NREL/SAM/issues/957

Best regards,
Paul.

Paul,

Do you know the most recent version where the annual degradation schedule feature is working, in case we need that feature before the next update rolls out?

Thanks.

Will

Hi Will,

This problem was introduced in SAM 2021.12.02, so SAM 2020.11.29 r2 or earlier should not have the bug.

Best regards,
Paul.