IAM method

What it is

Selects the angular-response curve: the share of the light the glass lets through at each angle of incidence, relative to normal incidence. It acts on the direct light, and on the sky and ground light through the diffuse integration.

Typical values and how to get it

Chosen on the Model tab.

Values

Auto = auto (default): the module's own table when it has one, else the Fresnel AR table · Fresnel, AR coating = fresnel_ar: a fixed table computed from the Fresnel equations for glass with an anti-reflective coating · Module IAM profile = module_profile: the module's own table, read by the rule its file declares (IAM table rule on the Module tab) · Fresnel, direct = fresnel: the Fresnel equations evaluated at every angle, for coated or plain glass as the AR switch says · ASHRAE b₀ = ashrae: the one-coefficient ASHRAE formula with b₀ · De Soto cover = desoto: refraction, reflection and absorption through the glass, with an anti-reflective coating when the AR switch is on · Tabulated = tabulated: linear interpolation of the table given in this section, or of the module's table when this section has none

References

1. Duffie & Beckman, Solar Engineering of Thermal Processes, 4th ed., Wiley 2013
2. De Soto, Klein & Beckman 2006, Improvement and validation of a model for photovoltaic array performance, Solar Energy 80(1) 78–88
3. ASHRAE Standard 93-2010, Methods of testing to determine the thermal performance of solar collectors (incidence-angle modifier)
4. IEC 61853-2:2016, Photovoltaic module performance testing and energy rating, Part 2: spectral responsivity, incidence angle and module operating temperature measurements

API

iam.kind