The turbine specifications are controlled by the turbine types dialog box. If you want to preserve the existing turbines, create a new one (Settings->Turbine Types->New). Use the dialog box that pops up here to set your rotor and hub height.
You can add turbines to your layout in a couple of ways:
- Manually - add a layer by right-clicking in the TOC pane and selecting 'New Layer->Turbine Layout'. Make the layer editable by selecting your new layerr and clicking on the Edit button (squiggly line + arrow icon to the right of the info button). The point and click in the main main window to add turbines.
- Using an existing point shapefile: File->Open Vector Layer and then
right click on the point layer in TOC and choose to 'Turbine Layout' in the pop up menu. This will make a Site Layout layer (in addition to your original point layer, but it uses the point layer to create the turbine locations.
In either case, once you have the locations, double click on your Site Layout layer and you can then either set all the turbines in one go (using the Set All Turbines button on the Site tab) or set turbine specifications individually (using the Turbines tab and iterating over them).
To calculate the ZVI (ZTV), right click on your DEM layer and select Properties. Go to the 'Interpretation' tab and select 'Terrain Elevation' from the 'To be Interpreted As' drop down dialog and check the units are correct. Now make the Site Layout a child of the Terrain (drag and drop it on top). Next go to Operations->Calculate ZVI. If the Site layout is not parented to the DEM your ZVI will show all turbines visible everywhere.