Hitachi claims a more moderate 30% power saving for inverter ac as compared to 50% claimed by panasonic. Both are in comparison to a 5 Star rated ac. There is no dispute on whether inverter ac will save power, question is how much?
Let's assume the lower 30% energy saving rate for our calculation. I could find the following online prices for Daikin A/c's..
Daikin 1.5 ton invertor split ac Rs 44,700
Daikin 1.5 ton 5 Star Split ac Rs 42,200
Daikin 1.5 ton 3 Star Split ac Rs 34,750
Let's assume a 1500 watt power input for a 1.5 ton 5 star split a/c (Typical). That comes to 1.5 Unit per hour of operation. Hp's usage is 8 hours a day for 6 month a year. Assuming Rs 7 Per unit rate in Maharashtra, the energy cost per month comes to Rs 2,520. With 30% saving in inverter ac, it will be Rs 1,764. So a saving of Rs 756 per month. Incremental cost of Daikin invertor ac compared to 5 star is Rs 2,500. So the payback period is approx 3.3 months after which savings actually start.
Further assuming DK's cost of Hitachi 1.5 ton 5 Star at 34K and HP's Panasonic invertor 1.5 ton at 45K, the difference is Rs 11,000. Payback period for an inverter ac in this case for HP's usage should Rs 11,000 / Rs 756 = 14.5 Months after which actual savings start.
Since ac's are used for atleast 5 year by normal people, prima facie, inverter ac does make sense and should save good amount of energy cost.
HP, calculate the above figures with actual price of models you are considering and you have the answer.