A solar system should be sized from your actual electricity use, not from a panel count. Start by listing every appliance, its power rating and how many hours a day it runs. That gives you the daily energy you need to replace.
Next, decide how much of that load must keep running when the grid is off. This sets battery size and the inverter rating. Ask any supplier to show how they calculated both.
Finally, check roof or ground space, shading, and who maintains the system after installation. A written scope and a maintenance plan matter as much as the equipment itself.