Welcome to the forum
Solar is a balance of your needs, conservation, enough battery to cover your needs while the sun doesn't play nice, enough solar to recharge those batteries back up when the sun does shine again, and a back up for when the sun hides too long.
Your needs can be calculated or if you know the size of the battery bank and how long it last, you have a rough guess to start with.
Conserve with LED lighting, lower power TVs. etc.
2 or 3 days of battery depending on your appetite, space and budget.
A 1-1 ratio of solar to Ah of battery or better so that you can recharge in a day. Dependent on roof space and budget.
A MPPT controller converts excess voltage to amps but they are more expensive. You have to look at what it offers to decide if it is worth the expense. sometimes another 12v panel will do better for you. Then again the big panels are even higher volatges and require the MPPT controller to be used at all. Those panels are cheaper per watt and offsets the extra cost some.
A 10 watt panel may keep a fully charged battery from self discharging if it is disconnected from any loads.