Describe the bug
The "dispatch hours" parameter does not account for the zero index of ppa prices, and leads to the battery charging at times that are more expensive than necessary.

To Reproduce
Steps to reproduce the behavior:

1. Run the SAM file attached to https://sam.nrel.gov/forum/forum-general/3979
2. See that the battery charges immediately, instead of waiting for the low price period in hours 5 and 6

Expected behavior
A 2 hour battery should charge during the lowest cost 2 hours