AC-Coupled PV + Battery with Grid IX Limit

Hello!
I'm attempting to model a Tesla Megapack-sized AC-coupled battery (1200kW |  with a 7.5 MWdc | 5.0 MWac PV system with a 4.0 MWac Grid Limit. I've set the FOM Storage Dispatch options to Automated Dispatch -> Charge from Grid-Limited System Power. I'm trying to understand why in the second screenshot it's not using the curtailed energy to charge the batteries in Hour 2552-2561, but it is for hours 2576-2580? Thank you- appreciate your expertise that I don't have in higher-level SAM analyses!

Hi Dave,

Please attach a copy of your .sam file if you would like me to help troubleshoot.

Best regards,
Paul.

Thank you Paul!

Hi Dave,

Thank you for sharing your .sam file.

The front-of-meter (FOM) automated disptach option in SAM includes a cycle degradation penalty in the dispatch decision. This is a way to account for the cost of potential battery replacements in the dispatch decision. In this case, SAM calculates the penalty and reports it in the time series results as "Battery computed cycle degradation penalty ($/cycle-kWh)" because Cycle degradation penalty option on the Battery Dispatch page is set to "Calculate automatically."

The calculated penalty is $0.0227405/kWhdc, which, based on a roundtrip efficiency estimate of 92%, is equivalent to $24.717/MWhac, so the automated dispatch algorithm only charges the battery if the "Power price for battery dispatch ($/MWh)" is greater than that value for one hour in the next 18 hours based on the 18-hour Look ahead period on the Battery Dispatch page.

You can get the battery to charge around Hour 2552 by setting the degradation penatly to $0.02/kWh, slightly lower than the calculated value: On the Battery Dispatch page, for Cycle degradation penalty option, choose "Enter penalty," and for Cycle degradation penalty, enter 0.02.

Best regards,
Paul.