Allow "Roll over net excess compensation to future bills" for Net metering with dollar credits

[brtietz]

AEP Ohio has a "net metering with dollar credits" format that never gets returned to the customer as a check, but does continuously roll over onto future bills:

(pg 1 of https://www.aepohio.com/lib/docs/cleanenergy/renewable/NetEnergyMeteringService2023-01-18.pdf)

SAM does not model this correctly currently, as net metering with dollar credits cash out at the end of the true up period. Investigate how to apply this checkbox to net billing with $ credits.