In this document
You'll learn how to use the 3rd component calculator to compute a missing solar parameter from the ones your dataset already has: choosing the parameter to calculate (GHI, DNI, DIF or ALB) and naming the new output column, selecting the input parameters, choosing flagging options (copying invalid flags from the reference parameters or running radiation QC on the new parameter), applying postprocessing with a low sun-elevation threshold, and saving the calculated column(s) to the dataset.
Prerequisites
An active Solargis Analyst account.
Installed an Analyst desktop application.
An available dataset in the Solargis Analyst application.
3rd component calculator
The 3rd component calculator computes a solar parameter from the other parameters in your dataset. It supports GHI, DNI, DIF and ALB. If your dataset contains only two of the three irradiance components, use this tool to calculate the third; if it contains GHI and RHI, you can use it to calculate albedo.
The methods the components are calculated are in the table.
Parameter | Calculated as |
|---|---|
GHI | DNI × sin(sun elevation) + DIF |
DNI | (GHI − DIF) / sin(sun elevation) |
DIF | GHI − DNI × sin(sun elevation) |
ALB | RHI / GHI |
Calculating the 3rd component
From the main menu, select Tools/Calculate 3rd component.
Select the parameter you want to calculate (GHI, DNI, DIF or ALB) and state its name. A new column with this name will be added to the dataset upon execution.
Select input parameters from the dropdowns. Some datasets may contain more columns of the same parameter type. Ensure you are selecting the correct ones. When you select ALB, an additional reference RHI dropdown becomes active. Use it to choose which RHI column to pair with GHI for the albedo calculation. This dropdown is inactive for the other parameter types.
Parameter flagging:
Copy flags from reference parameters: If selected, the related flag column is created and the invalid flags from the input parameters are copied to the calculated parameter. Only valid flags in the new parameter are overwritten, so flags already marking bad data are preserved.
Run radiation QC for calculated parameter: Runs a subset of the automatic radiation checks on the new parameter — invalid values, sun below horizon, and physical minimum and maximum — and flags values accordingly.
Choose postprocessing methods:
Limit for low sun elevation (deg): state the sun elevation threshold (in degrees) under which the values will not be calculated to avoid outliers.
Remove values (replace with NaN): Will remove outliers from the calculated parameter.
Flag values with flag: Values with a sun elevation between 0° and the threshold you set are flagged with the selected flag. Values with the sun below the horizon are not affected, so their existing sun-below-horizon flag is preserved.
Execute the calculation using the "Run" button, which is highlighted as the primary action until you run it for the first time. Once the run finishes, "Save" becomes the primary action and the results are ready to be written to the dataset.
Note: When you combine the options in step 4, they are applied in a fixed order — flags are copied from the input parameters first, then the automatic QC runs, then the sun-elevation check. At each stage, existing invalid flags are preserved and only the remaining valid values can be flagged.
Key points to remember:
You can calculate multiple parameters in this tool and save them all at once later. Names of already calculated parameters are listed in the orange text to avoid duplications.
New parameters are saved only after clicking the “Save” button. Clicking “Cancel” will discard the changes.
Input parameters must share the same unit. If they don't, the calculation is not performed and an error is shown.
If you close the window with unsaved calculations, a confirmation dialog appears first.