Windows files taking up a lot of space

Try clearing your temp folders first :3

It requires more detailed instructions but CCleaner has helped me tons. Try reading about it.

I have no clue which version of Windows you are running but I have Win10-64 bit running here and my total disk usage on my SSD is 17.4GB.

Sounds odd but if you've updated to windows 10 your previous windows is still there in case you change your mind. Win10 will eventually prompt you to get rid of it but...
Click in Windows' search field, type Cleanup, then click Disk Cleanup.
Click the "Clean up system files" button.
Scroll down the list until you see "Previous Windows installation(s)."
Check the box next to the entry, then make sure there are no other boxes checked (unless you do indeed want to delete those items).
Click OK to start the cleanup

If you haven't then you could use treesize to find out what the offending folder is and then google for a solution

Look at the temp dir in the windows folder and empty it. Can fill with crap so will get you some space back

try this tool, which will show what exactly takes space

Windows save all the updates backup in System32-softwaredistributionfolder. You can run windows update cleaner software to clear that folder, or you can also use disk clean up utility in advance mode to clean up backup files.
If you have not installed windows 10 yet then system might have downloaded the required files for upgrade on your system it should be a hidden folder in C drive by the name Windows BT (you can delete these files from disk clean up as well, there would be a check to remove installation files) but it will re download it if updates are set to automatic.

Ive been using SSD's for years now and every time i do a clean install of windows the page file is set way way to high and uses about 48 GB up on me because i have 32 gigs of ram sucking up tons of free space on your ssd,windows by default sets the page file/virtual memory to 1.5 x the amount of ram you have installed,if you have 16gigs of ram or more there really is no need to even have a page file running but i usually recommend setting it to 2-4 GB just to be safe,if you have 8gigs of ram i would set it to like 8GB and if you have less then i wouldn't mess with it, but im assuming you have 16 based on
http://windows.microsoft.com/en-us/windows/change-virtual-memory-size#1TC=windows-7

Maybe just reinstall Windows 10 if it gets too big. Takes like about 10 minutes for the install plus another 15-30 minutes for apps and softwares for an SSD.

Just to be sure, you've already right clicked on your C drive, gone to Properties, and used Disk Cleanup?
(This is the same approach as listed by Talgaby above, just a different access point.)

It must be Windows ghost files..like the ones used for System backup & restore.