The C# version of the N balance model is in the ModelCSharp dirrectory.
To use the prototype, you first need to build the solution. This will create several files in the bin directory, including the Excel add-in SVSModel-AddIn64.xll, which contains the model code.
Next, open Microsoft Excel and click on the File tab in the top toolbar. At the bottom of the tab, you will see an Options button. Click on it to open the options dialog box.
In the options dialog box, choose the Add-ins tab. At the bottom, there is a drop-down menu called Manage. Select Excel Add-ins and click on the Go button to open the Add-ins dialog box.
In the Add-ins dialog box, click on the "Browse" button, navigate to the ..\SVS\ModelCSharp\bin folder, and select SVSModel-AddIn64.xll. Click OK to add it to the list of available add-ins.
Still in the Add-ins dialog box, make sure the checkbox next to SVSModel-AddIn64 is checked, and click OK.
Now you can open the Prototype_V2.0.xlsm file in Excel, and you should have a working copy of the tool prototype.