wa alaikum salam wa rehmat ULLAH ,
im sorry i dont have n idea about that , but its a suggestion to consider a USED , APC on 24 volts . that will b much better than the Chinese or local one .
at olx there are many . i recently bought one for TESTING
regarding the data you provided 700 watts and 1200VA this means
700 / 1200 = 0.58 or 58 percent efficiency . that seems very bad . To understand this , lets suppose it will take 100 watts form your precious battery and then give you 58 watts only at 220 AC . So 42 percent of your battery current will b wasted into Heat . and you will only b able to get 58 watts against 100 watts input .
in case of pure sine wave , APC ups it is around 83 to 96 percent efficient !!!!! 96 percent efficiency at full load and 83 percent to 90 percent on half load (data taken from APC site) .