There is a convention on consistent variable names throughout the library:
.. glossary::
airmass
Airmass
airmass_absolute
Absolute airmass
airmass_relative
Relative airmass
albedo
Ratio of reflected solar irradiance to global horizontal irradiance
[unitless]
aod
aod500
aerosol optical depth [unitless]. Measure of aerosols (e.g., smoke
particles, desert dust) distributed within a column of air from the
instrument (Earth's surface) to the top of the atmosphere. The AOD
value indicates the level of extinction of sunlight in this column, and
when followed by a number (e.g. AOD500), indicates the extinction at
this wavelength (500nm).
aoi
Angle of incidence. Angle between the surface normal vector and the
vector pointing towards the sun's center. [°]
aoi_projection
cos(aoi). When the sun is behind the surface, the value is negative.
For many uses, negative values must be set to zero.
ape
Average photon energy
apparent_zenith
Refraction-corrected solar zenith angle. The solar
zenith angle describes the position of the sun relative to the vertical
and is defined as the angle between a vector pointed straight up and a
vector pointed at the sun, from the observer. [°]
apparent_elevation
Refraction-corrected solar elevation angle. This is the complement of
:term:`apparent_zenith` (90 - apparent_zenith). [°]
bhi
Beam/direct horizontal irradiance
clearness_index
clearness index [unitless]. Ratio of global horizontal irraidance to
the extra terrestrial irriance. The clearness index ranges between
0 and 1, with values closer to 1 indicating clear skies.
clearsky_index
clearsky index [unitless]. Ratio of actual global irradiance to modeled
clearsky global irradiance.
dhi
Diffuse horizontal irradiance
dni
Direct normal irradiance [Wm⁻²]. Irradiance received per unit area by a
surface perpendicular (normal) to the sun's rays that propagate in a
straight line from the sun.
dni_clear
Clear sky direct normal irradiance
dni_extra
Direct normal irradiance at top of atmosphere (extraterrestrial)
effective_irradiance
Effective irradiance
eta_inv
Inverter efficiency
eta_inv_nom
Nominal inverter efficiency
eta_inv_ref
Reference inverter efficiency
gamma_pdc
Module temperature coefficient. Typically in units of 1/C.
ghi
Global horizontal irradiance
ghi_clear
Clearsky global horizontal irradiance [Wm⁻²]
ghi_extra
Horizontal irradiance at top of atmosphere (extraterrestrial)
gri
Ground-reflected irradiance
i_sc
Short circuit module current
i_x, i_xx
Sandia Array Performance Model IV curve parameters
latitude
Latitude in decimal degrees. Positive north of equator, negative to
south.
longitude
Longitude in decimal degrees. Positive east of prime meridian, negative
to west.
pac, ac
AC power
pdc, dc
DC power
pdc0
Nameplate DC rating
photocurrent
Photocurrent
poa_diffuse
Total diffuse irradiance in plane [Wm⁻²]. Sum of ground and sky diffuse
components of global irradiance.
poa_direct
Direct/beam irradiance in plane [Wm⁻²].
poa_global
Global irradiance in plane. Sum of diffuse and beam projection [Wm⁻²].
poa_ground_diffuse
In plane ground reflected irradiance [Wm⁻²].
poa_sky_diffuse
Diffuse irradiance in plane from scattered light in the atmosphere
(without ground reflected irradiance) [Wm⁻²].
precipitable_water
Total precipitable water contained in a column of unit cross section
from earth to top of atmosphere
pressure
Atmospheric pressure
relative_humidity
Relative humidity
resistance_series
Series resistance
resistance_shunt
Shunt resistance
saturation_current
Diode saturation current
solar_azimuth
Azimuth angle of the sun in degrees East of North. The solar azimuth
angle describes the sun’s position along the horizon relative to the
observer. Azimuth is defined as degrees East of
North, so North = 0°, East = 90°, South = 180°, West = 270°.
solar_zenith
Zenith angle of the sun in degrees [°]. Zenith is the angle between is
between a vector pointed straight up and a vector pointed at the sun,
from the observer. Zenith is the complement of solar elevation, i.e.,
zenith = 90 - elevation.
spectra
spectra_components
Spectral irradiance (components) [Wm⁻²nm⁻¹]. The amount of energy
incident on a unit area per unit time and per unit
wavelength. As with broadband irradiance, global spectral irradiance
is composed of direct and diffuse components.
surface_azimuth
Azimuth angle of the surface in degrees East of North. Surface azimuth
is specified by the horizontal projection of the normal vector from
the surface. Azimuth is defined as degrees East
(clockwise) of North, so North = 0°, East = 90°, South = 180°,
West = 270°.
surface_tilt
Tilt from horizontal [°]. The surface tilt angle
is defined as degrees from the horizontal
such that a surface facing up would have a surface tilt of 0°, and one
facing the horizon would be 90°. [°]
temp_air
Temperature of the air
temp_cell
Temperature of the cell
temp_dew
Dewpoint temperature
temp_module
Temperature of the module
tz
Timezone
v_mp, i_mp, p_mp
Module voltage, current, power at the maximum power point
v_oc
Open circuit module voltage
wind_direction
Wind direction
wind_speed
Wind speed
For further explanation of the variables, common symbols, and units, refer to the following sources from SoDa Service:
Note
These further references might not use the same terminology as pvlib. But the physical process referred to is the same.