Can I upgrade the SSD of my Asus K551LN laptop?

[fiddle_1_]

So my laptop came with a 24 Gb ssd and I am planning to upgrade it to 240 gb. Question is, it is possible to do so and do I need a caddy bay in the process?
P/s: The backpanel can be detached and you could install 1 extra bar of RAM

 

[fiddle_1_]

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[RetiredChief]

1) The 24 GB SSD is NOT used like a normal SSD, instead it is used as a cache for the HDD.
SEE: Johnny's comment: http://www.tomshardware.com/answers/id-2738459/asus-k551ln-ssd.html
2) I saw a site that offered a upgrade to a 500 gig HDD which makes me think you could upgrade the HDD. would it work with out the SSD and Just a SSD (inplace of the HDD) ???
3) Me - I would pull the HDD and check to see if a SSD is compatible (ie size/and interface).
4) if OK from #2 then I would. A) Clone HDD -> SSD first. B) remove HDD, replace w/SSD check, If OK then try removing the SSD and recheck. OK then Done. If it worked with the 24 G SSD, but Not without, Then still OK, a slight slowdown from True SSD speed But still faster than a Cached HDD. Plus Most SSDs are More reliable than a Mechanical HDD.