Hi
I am modeling a net billing rate where a monthly minimum charge is in place. On SAM (v 2022.11.21) I observe the monthly minimum charges do not seem to be enforced for net billing.
How to reproduce the issue:
1) Start a new PVWatts residential model with default settings.
2) 'Electricity Rates': Set Monthly minimum charge to $10. Leave the default value of 'Metering and Billing' as 'Net energy metering'
3) 'System Design': Set system nameplate capacity to 100 kWdc (to model scenario with large exported energy)
4) Simulate. Annual bill with system is $120 (12x$10) as expected. Monthly minimum charge is being applied. Good.
5) Now change 'Metering and Billing' to 'Net billing'. In 'Rates for Energy Charges', set the 'Sell ($/kWh)' to 10 for all tiers (to model high value exports that will lead to a negative bill if the monthly minimum charge is not applied).
6) Simulate. The annual bill with system is a very large negative number, i.e. the monthly minimum charge has not been applied.
I've uploaded a SAM file that shows the Net Billing case.
Is this a bug or am I missing something? If the latter, is there another way to enforce this minimum bill?
Thank you very much!