Data Parameter Definitions

Data Parameter Definitions

Parameter Definitions

This page provides detailed explanation on the parameters that are available within the Solcast API.

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Name
Definition
How we use this
Unit
Valid range
Defaults
Name
The user-defined name of the site.
Used to display a name for your site. Can be changed.
N/A
None, required
Latitude
Site latitude (centre of site) in decimal degrees (EPSG:4326).
Used to locate your site.
°
-90 to +90
None - Required field
Longitude
Site longitude (centre of site) in decimal degrees (EPSG:4326).
Used to locate your site.
°
-180 to +180
None - Required field
Tracking type
The type of sun-tracking or geometrical configuration of your site's modules
Used to calculate the incident irradiance for your modules
N/A
"fixed_tilt" or "horizontal_single_axis"
None - Required field
Install date
The date when your site was installed
Used to derate your module (DC) production gradually with age, at a rate dependent on your Module Type
date
1970-01-01 to present date
1 year before date at site creation
AC capacity (inverters)
Total inverter (nameplate) capacity in MW. This is the highest potential output of the system before any Site Export Limit is applied
Used to model the conversion of DC power to AC by your inverters
MW
>=0
None – Required field
DC capacity (modules)
Total module capacity in MW. Usually slightly higher than the AC capacity.
Used to model the generation of DC power by your modules
MW
>=0
1.27*AC capacity
Grid export limit
The maximum power export limit in MW that is allowed by the site's connection with the network operator
Used to place a final cap on your AC power output. Only impacts your AC power if the grid export limit is set lower than the AC capacity
MW
>=0
Disabled
Name
Definition
How we use this
Unit
Valid range
Defaults
Other losses derating coefficient
The factor by which the whole system will be derated due to causes other than temperature and degradation.
Used to calculate other system losses including mismatch, wiring and connection.
fraction
0 to 1
Inferred from AC capacity if not specified
Age degradation derating coefficient
The factor by which the whole system will be derated per year since the Install Date.
Used to calculate time dependent system loss.
year-1
0 to 1
0.0023 (mono-Si) 0.0059 (poly-Si) 0.0095 (a-Si) 0.0030 (CdTe) 0.0002 (CIGS)
Peak inverter efficiency
The peak efficiency value in your inverter efficiency curve.
Used to scale the conversion efficiency of DC to AC, as a function of the inverter load.
fraction
0 to 1
0.985
Module temperature derating coefficient
The factor by which your site's module (DC) production will be derated with increasing temperature.
Used to derate your module (DC) production gradually with increasing temperature.
K-1
-1 to 0
0.0039 (mono-Si) 0.0039 (poly-Si) 0.0031 (a-Si) 0.0026 (CdTe) 0.0042 (CIGS)
Ground coverage ratio
The proportion of the site's ground area covered by modules.
Used to calculate the incident irradiance for your modules.
fraction
0 to 1
0.36 if tracking_type is horizontal_single_axis 0.47 if tracking type is fixed
Module type
The type of material or technology used in your site's PV modules.
Used to estimate your module temperature derating coefficient (unless you specify your own coefficient) and used to estimate your module age derating.
N/A
Monocrystalline Silicon (mono-Si) Polycrystalline Silicon (poly-Si) Amorphous Silicon (a-Si) Cadmium Telluride (CdTe) Copper Indium Gallium Selenide (CIGS)
Polycrystalline Silicon (poly-Si) if install date is >= 2013 Monocrystalline Silicon (mono-Si) if install date < 2013
Name
Definition
How we use this
Unit
Valid range
Defaults
Module azimuth angle
The off-north-facing direction on the horizon in which the modules are facing for a fixed-tilt site.
Used to calculate the incident irradiance for your modules.
°
-180 to 180. South is -180, East is -90, North is 0, West is 90
Set to 0 if latitude is less than zero, otherwise set to 180
Module tilt angle
The off-horizontal tilt angle of modules for a fixed-tilt site.
Used to calculate the incident irradiance for your modules.
°
0 to 90. Zero means the modules are horizontal
Quadratic function of site Latitude
Name
Definition
How we use this
Unit
Valid range
Defaults
Tracker smart tracking
Whether the trackers move to horizontal during cloudy periods with zero DNI, for a horizontal single axis tracking site.
Used to calculate the incident irradiance for your modules.
boolean
True, False
False
Tracker back-tracking
Whether the trackers backtrack at low solar elevation angles, for a horizontal single axis tracking site.
Used to calculate the incident irradiance for your modules.
boolean
True, False
True if install date is >Jan 2015, else False
Tracker maximum rotation angle
The maximum off-horizontal angle for a horizontal single axis tracking site.
Used to calculate the incident irradiance for your modules.
°
0 to 90
50 °
Tracker axis azimuth angle
The off north-south azimuth angle for a horizontal single axis tracking site. Most commonly this will be close to zero.
Used to calculate the incident irradiance for your modules.
°
-180 to 180. South is -180, East is -90, North is 0, West is 90
0 (north-south axis)
Name
Definition
How we use this
Unit
Valid range
Defaults
Topographic horizon elevation
The elevation angle of topography (e.g. hills and mountains) surrounding the general area of your site, at a set of specified different azimuth (direction) angles.
Used to calculate the incident irradiance for your modules
°
0 to 90 for each elevation value. -180 to 180 for each azimuth value. The list must have the same number of azimuths and elevations
0° elevation at every azimuth
Average dust soiling losses
The average proportion of module production lost due to dust soiling, from 0 to 1. E.g. 0.02 for April means a 2% soiling loss will be applied throughout April. The value entered should reflect the impact of cleaning activity at your site.
Used to calculate the module (DC) production We accept either a single yearly average value, or a set of 12 monthly average values.
fraction
0 to 1
0.015
Average terrain azimuth
The average terrain slope downhill direction.
Used to calculate the incident irradiance for your modules. Terrain Azimuth is meaningful only when terrain_slope>0.
°
-180 to 180. South is -180, East is -90, North is 0, West is 90.
Average terrain slope
The average terrain slope in degrees of your site. A site with no terrain slope has a value of zero.
Used to calculate the incident irradiance for your modules.
°
0 to 90

"apply" plant condition parameters

These optional parameters exist to accommodate deviations in the actual operating condition of the plant, which can vary from minute-to-minute or day-to-day and therefore are not suitable to be semi-permanent plant specification metadata like the parameters above. When these parameters are not used, the above plant specification metadata is used. The "apply" parameters can be optionally specified in the API request, with no delay in receiving forecasts back from the Solcast API. Not all "apply" parameters need to be provided in the request, only the parameters relating to the actual changes in plant operating conditions.

Name
Definition
How we use this
Unit
Valid range
Defaults
apply_tracker_inactive
Indicating if trackers are inactive. If True, panels are assumed all facing up (i.e. zero rotation). Only has effect if your site has a tracking_type that is not "fixed".
Used to calculate the module (DC) production
Boolean
True-False
False
apply_snow_soiling
A user-override for Solcast's dynamic snow soiling, which is based on global snow cover and weather forecast data, and changes from hour-to-hour. If you specify this parameter in your API call (e.g. if snow clearing has just been performed), we will replace the Solcast dynamic hour-to-hour value with the single value that you specify. E.g. if you specify a 0.7 snow soiling, your returned power will be reduced by 70%.
Used to calculate the module (DC) production.
boolean
True-False
False
apply_dust_soiling
A user-override for dust_soiling_average. If you specify this parameter in your API call, we will replace the annual or monthly average dust soiling values for the site with the value you specify in your API call. E.g. if you specify a 0.7 dust soiling, your returned power will be reduced by 70%.
Used to calculate the module (DC) production.
boolean
True-False
False
apply_constraint
Constraint on site's total AC production, applied as a cap in the same way as the metadata parameter Site Export Limit. This will constrain all Solcast power values to be no higher than the apply_constraint value you specify. If you need an unconstrained forecast, you should not use this parameter.
To adjust the pv power value returned by the Solcast API.
boolean
True-False
False
apply_availability
Proportion of the site's total AC (inverter) capacity that is currently generating or expected to be generating during the forecast request period. E.g. if you specify a 30% availability, your returned power will be a maximum of 30% of AC capacity.
To adjust the pv power value returned by the Solcast API.
boolean
True-False
False