Model step
Perez settings
Coefficients and inputs of the Perez model
Inputs used: Direct normal irradiance, Station pressure, Altitude
What it is
Each option of this step fixes the inputs and constants the Perez equations leave open: the solar constant and its eccentricity factor, the source of the direct normal irradiance, the air-mass formula of the sky brightness, an altitude factor and three limits on intermediate values. The equations and the coefficient table are those of the Perez 1990 transposition. The step has no effect unless the transposition model is Perez.
Options
- PVsyst 8 settings: 1361 W/m², the direct normal irradiance computed from the global and diffuse values, a 0.9 cap and the Kasten 1966 air mass
- Published settings: the published form, with the file's direct normal irradiance and a solar constant of 1367 W/m²
- NREL SSC settings: 1367 W/m² with no eccentricity, the file's direct normal irradiance and the Kasten 1966 air mass
References
- Perez, Ineichen, Seals, Michalsky & Stewart 1990, Modeling daylight availability and irradiance components from direct and global irradiance, Solar Energy 44(5) 271–289
API
array.perez_settings = pvsyst_8 | published | ssc