Transposition models split the diffuse irradiance into several components, including circumsolar, isotropic and horizon brightening. The main output of a transposition model is the irradiance on a tilted surace, poa_global, and its component, including poa_direct, poa_diffuse, poa_sky_diffuse, poa_ground_diffuse.
pvlib's general purpose transposition function (get_total_irradiance) attibutes the circumsolar irradiance in poa_sky_diffuse.
In contrast, pvlib's two view factor models infinite sheds and ANTS-2D attribute the circumsolar irradiance to poa_direct.
The argument for including circumsolar in poa_sky_diffuse is that it is measured diffuse irradiance. The argument for including circumsolar in poa_direct is that the irradiance originates from around the sun disk and thus is treated as direct irradiance when transposing irradiance or estimating angle of incidence losses.
Transposition models split the diffuse irradiance into several components, including circumsolar, isotropic and horizon brightening. The main output of a transposition model is the irradiance on a tilted surace,
poa_global, and its component, includingpoa_direct,poa_diffuse,poa_sky_diffuse,poa_ground_diffuse.pvlib's general purpose transposition function (get_total_irradiance) attibutes the circumsolar irradiance in
poa_sky_diffuse.In contrast, pvlib's two view factor models infinite sheds and ANTS-2D attribute the circumsolar irradiance to
poa_direct.The argument for including circumsolar in
poa_sky_diffuseis that it is measured diffuse irradiance. The argument for including circumsolar inpoa_directis that the irradiance originates from around the sun disk and thus is treated as direct irradiance when transposing irradiance or estimating angle of incidence losses.