Simple battery model v detailed battery model

Hi there, I have been looking through the documentation for the simple (Battwatts) and detailed battery models for information and can gleam that there are far fewer user inputs for the simple model. Overall, I'd like to understand their use cases better - what can each model do that the other cannot / are both applicable to utility-scale PV-Battery systems? 

I ran the default values on the SAM desktop app for the Li-ion configuration (simple model) and LFP/Graphite + 2 other Li chemistries (detailed model) and they did not yield the same results as I would have assumed the simple model would aim to achieve. The biggest difference was in the Annual AC energy in Year 1 and some financial parameters. Are the financial models different between models? Can I calculate how much of the annual AC energy in Year 1 passes through the battery?

My original assumption was that the simple model just uses a lot of defaults the user cannot change but in looking through the code repo it seems the model is just generally different so I'd be interested in learning more about what differs mathematically and/or physically between the models.

Thank you! Trinity

Hi Trinity,

The Battwatts module in PySAM and PVWatts-Battery configurations in SAM are intended to model for behind-the-meter (BTM) batteries for peak shaving applications where the battery dispatches to reduce demand charges in the system owner's electricity bill.

The custom dispatch option is available if you have time series dispatch data from another model.

You are correct that the Battwatts module in PySAM uses the same underlying code as the Battery module, but with fewer inputs and options.

In general, unless you are modeling a battery designed for peak shaving with a BTM financial model (Residential, Commercial, Third Party Ownership), I would recommend using the Battery / Pvsamv1 modules in PySAM or Detailed PV model in SAM, which you can use with either BTM or front-of-meter (FOM) financial models.

Best regards,
Paul.

Hi Paul,

Thank you for the quick response and clarification! I have a better understanding of the modules now.

Best regards,
Trinity