Hello,

This sample code demonstrates how to set solves from Excel API.
The example below applies an F# solve:

Dim Surface_Last As ILDERow
Set Surface_Last = TheLDE.GetSurfaceAt(TheLDE.NumberOfSurfaces - 2)


Dim Solver As ISolveData
Dim SolveFNumber As ISolveFNumber
Set Solver = Surface_Last.RadiusCell.CreateSolveType(SolveType_FNumber)
Set SolveFNumber = Solver.[_S_FNumber]
SolveFNumber.FNumber = 3.1
Surface_Last.RadiusCell.SetSolveData Solver

For further examples about how to use the Excel API, please take a look at these sample files:
ZOS-API and Excel | Zemax Community