Hi Chandiranselvam,
The solar panels are rated as per their capacity. A solar panel typically is rated at 120W. A 5 HP pump needs 5 * 745.7 = 3728 watts of power to run.
Hence you can calculate the number of solar panels needed for your 5 HP pump.
The cost usually will be about 40 - 50 rupees per watt "only" for the solar panel and hence only for the solar panel the approximate cost will be 3728 * 50 = 1,86,000 rupees.
Additional cost will be for batteries and other infrastructure.
Subsidy is available in TN, but I am not sure how much. Not sure about other states.
Regards
Shanmugasundaram.M