Battery subhourly custom time series dispatch

Hello everyone,
For battery merchant project with 15 min custom time series dispatch, SAM 2022.11.21  finishes with the following notices:
"exec fail(battery): Invalid custom dispatch length, must be 8760 * steps_per_hour
Simulation battery failed :exec fail(battery): Invalid custom dispatch length, must be 8760 * steps_per_hour
monthly_grid_to_batt not assigned
Simulation merchant plant failed : monthly_grid_to_batt not assigned".
Dispatch length 35040 is automatically set by SAM and it looks correct.
How to correctly configure battery dispatch with suhourly custom time series? Thank you
 

Hi Danichkov,

SAM does not automatically adjust the length of the custom time series dispatch array. If you choose a weather file with 15-minute time steps on the Location and Resource page, you have to set the time step for the battery dispatch to 15 minutes:

1. On the Battery Dispatch page, choose Dispatch to custom time series.
2. Under "Dispatch to Custom Time Series," click Edit array.
3. In the Edit Array window, click Change time step, type 15 for the time step in minutes, and click OK.
4. Use the Paste or Import buttons to set the 35,040 values in the table, and click OK.

 

If you did follow these steps, please attach a copy of your .sam file so I can help troubleshoot.

Best regards,
Paul.

Hi Paul,Thank you for your prompt reply. Please see attached project.Best,Dmitri 

Hi Dmitri,

Thank you for sending the file.

This is a bug for standalone front-of-meter configurations with custom time series dispatch and sub-hourly time steps that we will fix in an update to SAM 2022.11.21. We are currently finishing up work on Revision 1, so this may have to wait until Revision 2.

github.com/NREL/ssc/issues/994

The problem is that the Standalone Battery / Merchant Plant configuration assumes an 8760 simulation. PV-battery configurations use the weather file to identify the simulation time step. Behind-the-meter standalone batteries use the load data to identify the simulation time step. The front-of-meter standalone battery configurations (Merchant Plant and PPA financial models) do not have weather data or load data, so they are unable to identify the correct time step.

As a workaround, you can model the standalone battery using the PV Battery / Merchant Plant configuration with a 15-minute weather file, AC-connected battery, and DC losses set to 100%. I have attached a modified version of your file that demonstrates this workaround. (On the Losses input page, you can either set the DC losses to 100%, or the constant "availability" loss to 100% -- both methods are demonstrated in the file.) I also attached a 15-minute weather file for this workaround -- its only purpose is to identify the simulation time step.

Best regards,
Paul.

Paul,
Thank you for your help
Best,
Dmitri