Modeling of an Off-Grid, DC only system with SSC SDKTool

I'm hoping to model an off-grid, dc-only system using a combination of SSC SDK and Excel. It looks like I can use wfreader, irradproc, and pv6parmod to get hourly dc output, then I can use Excel to derive the battery SOC for each hour. FYI, I am also using the CEC Modules.csv file that I dug out of the SAM folders, which gives me the pv module coefficients that are needed for pv6parmod. I not able to find much documentation for pv6parmod. Assuming this is the right approach, which model does pv6parmod use for dc output? Also, does it apply a reflectance (as a function of incident angle) for the calculation of temperature and/or dc output? And, since it doesn’t ask for shading, soiling, and etc., does it make sense to derate the poa output from irradproc prior to running pv6parmod?

Dear Adam,

The pv6parmod compute module in SSC is an implementation of the single-diode equivalent circuit model described in Section 10.4 of the SAM Photovoltaic Model Technical Reference Update, which you can download from the Performance Model Documentation page:

sam.nrel.gov/performance

You should be able to find answers to your questions in the reference manual.

The model is also descrribed on the PV Performance Modeling Collaborative website:

pvpmc.sandia.gov/modeling-steps/2-dc-module-iv/diode-equivalent-circuit-models/de-soto-5-parameter-model/

SAM's shading models are separate from the module model. The approach you describe of derating the POA data from the irradproc module would account for the reduction in POA irradiance, but would not account for effects of partial shading of the array.

Best regards,
Paul.