System Restore is for restore points. Those are cleared by a clean install, even just an upgrade-install will clear them. As Igor Leyko said, make a Windows system image backup. Then, you'll see how to restore it in the links below.
It makes a backup of all the Windows partitions required to boot & run Windows: EFI, MSR, Windows (C:), & Recovery. If you've got additional partition(s), they will also be offered for inclusion. A 2 TB external HDD is large enough to never fill with images. An 8 GB flash drive should be large enough to hold a Recovery drive (used to restore an image).
I make one after each new OS Build comes in & runs well, & I keep the last three...
I rename the computername folder which is inside the WindowsImageBackup folder (by adding the OS Build to it) in order to keep them separate & distinct. All three will be offered during the restore process.
Make it at "START, Settings, Update & Security, Backup, Go to backup & Restore (Win 7), Create a system image". Afterward, make the Repair Disc or (even better) ask Cortana for Recovery Drive to put it on USB. That can be used to do a restore. Then see the following to know how to restore one...
How to restore a Windows 10 system image to an existing or larger storage device
https://www.winhelp.us/restore-a-system-image-in-windows-7.html
Restore a System Image Backup in Windows 7, 8, 8.1 and 10
Note: That is an informative 3rd-party site, but I know nothing (good or bad) about any downloads or links that are there (or anywhere else).
If your external hard drive (or the internal one I guess) is a Seagate or Maxtor, there will be a free version of Acronis True Image at their site. Seagate calls it DiscWizard. Macrium Reflect, AOMEI Backupper & others also offer free versions of their image makers. These 3rd-party apps are quicker, make more compact images, & are more flexible in use. But the Windows version works in under 15 minutes on my small & uncomplicated system. I must add, DiscWizard's Bootable Media (to restore an image when Windows won't boot) requires a Mouse to operate. Plug one in, & it is instantly recognized.