Private Sub RadButton1_Click(sender As Object, e As EventArgs) Handles RadButton1.Click 
        Dim _exporter As New GridViewSpreadStreamExport(Me.RadGridView1)
        _exporter.ExportVisualSettings = True
        Dim fileName = "..\..\exportedFile" & DateTime.Now.ToLongTimeString().Replace(":", "_") & ".xlsx"
        _exporter.RunExport(fileName, New CustomSpreadStreamExportRenderer())
        Process.Start(fileName)
    End Sub

    Public Class CustomSpreadStreamExportRenderer
        Inherits SpreadStreamExportRenderer
        Public Overrides Sub SetRowHeight(height As Double, inPixels As Boolean)
            Dim maxRowHeight = 409 
            If height > maxRowHeight Then
                height = maxRowHeight
                inPixels = False
            End If
            MyBase.SetRowHeight(height, inPixels)
        End Sub
    End Class