Is this how much i am really supposed to get from a 5kw system?

So i have a 5kw grid tie system located in Quezon City, Philippines, the panels are facing west and tilted following the slope of the roof. but i dont know if i did some installation wrong that is causing me to only get this production. i just installed it the whole system myself last Feb 8,2017. Is this production just typical?
Lowest Production:
Feb 17,2017 - 6.5kwh
Feb 18,2017 - 6.8kwh
Previous Days Production:
Mar 6,2017 - 19.7kwh
Mar 7,2017 - 18.8kwh
Mar 8,2017 - 11.3kwh
Mar 9,2017 - 16.5kwh
Highest Production so far:
Feb 15,2017 - 20.9kwh
Typical Production:
10-15kwh/day
Solar System:
Solar Panels: 20-260w trina solar panels - http://static.trinasolar.com/sites/default/files/PS-M-0323%20E%20Datasheet_Allmax_US_Feb_2017_A.pdf
Inverter: Growatt 5000UE - http://www.growatt.com/html/2014/01/10/2014011010480983423919.html
I used 4mm2 pv cable that run a length of approx 25m.

Should i also use a thicker pv cable? and is the Current from the panels a little high for the inverter?