Use this battery calculator to convert Ampere hour to Kilowatt hour etc.
You can only change the RED cells.
Discharge time is basically the Ah rating divided by the current.
Example: Battery AH X Battery Volt ÷ Applied load.
So, for a 110Ah battery with a load that draws 20A you have: #110÷20 =5.5 hours.
The charge time depends on the battery chemistry and the charge current. For NiFe, for example, using Solar this could typically be <65% of the Ah rating for 4~6 hours. Other chemistries, such as LiFe & LiMh batteries will be different.
Say, 1200Ah x 48V÷1000 Watts =12 hrs (with 40% loss at the max = 48x40÷1000 =1.92 hrs).
For sure, the backup may lasts up to 4.8 hrs at 100% efficiency.
#1200mAh is the same as 1.2Ah. 300mA is the same as 0.3A
Wh = Ah x Voltage, where 1kW = 1000W.
"C" Rating is the Battery Charge or Discharge Rate.