Retail Rates Dispatch has trouble with high load, low cost periods

[brtietz]

Describe the bug
A user reported a case where the retail rates dispatch fails to take advantage of a price differential because of differences in load - the largest load is at the lowest cost times and this prevents the battery from charging.

To Reproduce
Steps to reproduce the behavior:

1. Download and open the attached case
   BTM Battery Examples.zip

2. Run the file

3. See a lot less battery charging and discharging than expected.

Expected behavior
Retail rates dispatch was written before we had a stand-alone battery model. Re-examine the charging and discharging assumptions with a stand alone battery in mind.

[brtietz]

#1354 included commits that solved this issue.