Steps for SketchUp: http://www.sketchup.com/download

1. First download and install SketchUp
2. Open SketchUp 2016 file from desktop shortcut
3. First time when you open SketchUp, it'll ask you to choose a template.
4. Select: Simple/Basic template (m)
5. Then click on 'Start using sketchup' to open the software.
6. Once open, close the software, as you've to install the Skelion Plug-in

Steps for Skelion: http://www.skelion.com/

1. Now install the 7-Zip software, this is needed for extracting Skelion file
2. Then, right click on skelion .rbz file, select 7-zip, and click on 'extract here'
3. You'll see 1 file and 1 folder being extracted
4. Select both file and folder and copy them to paste in the following destination:
   C:\Users\......\AppData\Roaming\SketchUp\SketchUp 2016\SketchUp\Plugins
5. After pasting both the extracted items here, restart the SketchUp software
6. Now go to Window->Preference->Extensions
7. Select the Skelion checkbox
8. A new window will appear in the side, click on Accept, to accept the terms and condition
9. Then click ok
10. Again restart the sketchUp software
11. You are good to go from here.

7-Zip extractor: http://www.7-zip.org/download.html

The PVSYST can be downloaded from: http://www.pvsyst.com/en/