Subarray Module Efficiency Calculation

  • gustavorch
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11 Dec 2022 15:16 #11770 by gustavorch
Subarray Module Efficiency Calculation was created by gustavorch
Dear SAM team, 

I'm trying to find the formula which calculates the subarray module efficiency (subarray1_modeff) but I can't find it on SAM documentation. Could someone shed a light on this? I can see there is a variation on module efficiency when albedo and POA rear side irradiation are at very high values, but I'm trying to understand why this variation is happening. Appreciate your feedback on this topic.

Best Regards,

Gustavo Rocha 

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  • pgilman
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04 Jan 2023 16:46 #11804 by pgilman
Replied by pgilman on topic Subarray Module Efficiency Calculation
Hi Gustavo,

SAM calculates the module efficiency after calculating the power output to report as a model output. The efficiency is not used to calculate the power output. For more detail about SAM's PV models, see the PV technical manual referenced here: sam.nrel.gov/photovoltaic/pv-publications.html.

For the CEC Module model, the module efficiency is calculated using the equation

eff = P / ( A * G )

Where:

eff = module efficiency
P = array DC output in W
A = array area in m2
G = array POA irradiance in W/m2

See the attached Excel file for an example.

The source code for this calculation is here: github.com/NREL/ssc/blob/4cbf27085c17d39140ea444c514431907d072a15/shared/lib_cec6par.cpp#L199

Best regards,
Paul.

 
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