Erroneous PPA model warning message with battery replacements 

Forum post:

https://sam.nrel.gov/forum/forum-general/3315

![image](https://user-images.githubusercontent.com/6498311/106273244-90d6b400-61ef-11eb-8eb3-de38d2fa6921.png)
![image](https://user-images.githubusercontent.com/6498311/106273259-97652b80-61ef-11eb-9383-109c7f86d749.png)
