The backup time mentioned is 8 hours for 5 fans + 5 lights + 2 TV. But what is the battery capacity needed for this? The power output should be (5 fans = 5x80W) 400 W + (5 lights = 5x30W CFL) 150 W + (2 TV = 2x100W) 200W = 750W. For 8 hours it should be 750x8 = 6000 Watt Hour. Considering the effeciency of 80% as stated in the product specification, the battery capacity needed is 6000 / (12 x 0.8) = 625 Ampere Hour. That means if we consider each battery of 150 AH capacity, we need over 4 batteries to give such a backup. Hence this 8 hours of backup time is purely misleading without specifying battery capacity. I am giving a 5 star as the product is good, but you can be easily fooled if you do not understand the basics and just go by the description of specifications.