DC degradation check flags degradation less than 100% as error

[cpaulgilman]

Describe the bug

For the Detailed PV model with Annual DC degradation rate specified as an annual schedule, SAM displays a simulation error "Degradation calculated to be greater than 100%, capped at 100%" when degradation inputs are valid.

See https://sam.nrel.gov/forum/forum-general/3772

To Reproduce

Steps to reproduce the behavior:

1. Create a default Detailed PV / Single Owner case.
2. On the Lifetime and Degradation page, click Val/Sched, Edit and set degradation for Year 2 to 6.
3. Click Simulate. Note error message and, on Cash Flow tab, electricity to grid for Year 2 is zero.