Subarray 1 String short circuit DC current

Hello,

I would like to know how is SAM calculating "Subarray String short circuit DC current"?

Does SAM uses ISC (short-circuit current) equations from the Sandia “Photovoltaic array performance model” to calculate short-circuit current? IF so, I am seeing different results. I took hourly irradiance and cell temperature output from SAM and calculated the hourly ISC. My calculation for the maximum current value came as 17.65 Amps whereas in SAM I am seeing 17.9 Amps. 
could you please share the helpful resource if the calculations are different from the PV performance model?

Also, since we are using a Bifacial module, is there a way we get rear side or total irradiance before IAM losses? I don’t see this option available in the Lifetime hourly data tables.
 “Subarray 1POA rear side total irradiance (W/m^2)”  before reflection (IAM)
“Subarray 1POA total irradiance (W/m^2)”  before reflection (IAM)

Thanks
NG

Hi Naga,

How SAM's photovoltaic model calculates the short circuit current depends on the option you choose on the Module page. If you choose the Sandia module model, then the calculations will use the empirically-derived equations you show below. Otherwise, if you choose the "CEC" module model, the calculations are based on a different single-diode model.
 
These models are described in the Photovoltaic Technical Reference Update, which you can download from the SAM website at sam.nrel.gov/photovoltaic/pv-publications.html .

Best regards,
Paul.