If you enter a DC degradation rate > 100% in the detailed PV model, you get nonsensical degradation outputs. (Granted, a degradation rate > 100% is a nonsensical input, but it's not prohibited in any way at the moment). Need to add a check to cap the degradation at 100%. The outyears energy still appears to be correct, as DC performance isn't calculated to be negative.

To Reproduce
Steps to reproduce the behavior:

1. Open a Detailed PV/Residential Case
2. Go to the "Lifetime and Degradation" page
3. Enter 105%
4. Click simulate
5. View the "Annual DC Degradation Factor" output to see nonsensical results.