Currently, the definition of module efficiency (passed out of the module model as out.Efficiency and accessed as subarrayX_modeff) when using the mlm module model is inconsistent with the definition of all the other available module models.
In the mlm model, efficiency = output_power / (collector_area*poa_eff), where poa_eff is the total irradiance after module cover effects (in keeping with the output definitions in the latest release). In all other module models, efficiency = output_power / (collector_area*poa_shaded_soiled), such that the given module efficiency includes module cover effects.
A simple solution would be to change the implementation of the mlm model, but I think this brings up the larger question of how module efficiency should be defined in ssc/SAM. When I first used ssc I was surprised to find that efficiency was defined relative to poa_shaded_soiled, since other software (namely PVsyst) defines it relative to poa_eff. Also, defining it relative to poa_eff aligns with the way the name plate rating of a module is defined (it also does not consider angle of incidence effects).
I am sure there are good reasons to define it relative to poa_shaded_soiled, but I hope this request will eventually result in a standardization of the calculation.
Currently, the definition of module efficiency (passed out of the module model as
out.Efficiencyand accessed assubarrayX_modeff) when using the mlm module model is inconsistent with the definition of all the other available module models.In the mlm model, efficiency = output_power / (collector_area*poa_eff), where poa_eff is the total irradiance after module cover effects (in keeping with the output definitions in the latest release). In all other module models, efficiency = output_power / (collector_area*poa_shaded_soiled), such that the given module efficiency includes module cover effects.
A simple solution would be to change the implementation of the mlm model, but I think this brings up the larger question of how module efficiency should be defined in ssc/SAM. When I first used ssc I was surprised to find that efficiency was defined relative to poa_shaded_soiled, since other software (namely PVsyst) defines it relative to poa_eff. Also, defining it relative to poa_eff aligns with the way the name plate rating of a module is defined (it also does not consider angle of incidence effects).
I am sure there are good reasons to define it relative to poa_shaded_soiled, but I hope this request will eventually result in a standardization of the calculation.