What will be the minimum quantity of solar panels needed for a pantahouse?

This question overloaded with a series of "It depends".

But, given the available information, I say about 15.

It's a trick question. You can't use solar panels on Pantahouse clothing.

You need 4 solar panels of 300KW capacity per 1 KW solar PV system. Now just calculate the power consumption per month of your penthouse. You can do it by calculating average units consumption of electricity from last 12 months utility bills. Lets assume your penthouse consume 20 units of electricity per day, so you need 4 KW solar PV system installed on your penthouse(1 KW solar panels system produce 5 units per day approximately).