There are different factors which must be put under consideration before the size of Solar PV System is determined. The physical size of the house, number of people living in it, star rating of the appliances, number of appliances, usage habits, swimming pool, air conditioning, heating system and many other factors.
Electricity bill needs to be analysed and number of unit consumed during a period needs to been seen. Other factors like weather and seasons are also significant factor in the decision making process. It is highly recommended to see a consultant before deciding which system should be installed.
Below are some approximate sizes of the system and their relative costs. These figures and values are on approximate basis and may or may not be true for an individual household.