Florida is a net metering at retail pricing state if the internet is not misleading me, so think of your electricity like water. When your house is using more than your panels are producing, the electricity flows into your house from the grid, and you rack up a bill for that energy. But when your panels are producing more than your house needs, the electricity flows out to your neighbors, and you earn credit for that energy.
Your house will use a certain amount of power each day, and your panels will produce a certain amount. Over the course of the month, all that matters is the total at the end of the billing period. You don't have to care about when you're using vs producing. Therefore you only need to consider Powerwalls if you either want to protect against grid outages or you want your home to be 'truly' solar-powered at all times rather than just on a net basis. But beware that adding Powerwalls will drastically increase the total system price and likely extend the payback period. That's not to say don't do it--I think it'd be awesome if money were no object for me.
The specifics of how long it'll take before the system 'pays for itself' will depend significantly on what you pay currently for power, whether your utility actually does pay retail rates for net-metered power, and whether you can get on a time-of-use power plan (where you pay more at 'peak' times during the day, and less at night--these tend to work out spectacularly well for EV owners with solar, since you produce at the peak times and can easily schedule your biggest power consumer-your cars-to charge at the cheapest time overnight).
So let us know those specifics. I would also
put in an order with Tesla, as it's a refundable $100 that will get you an actual design on your actual roof's specifics and a consultation with someone who knows your local situation. My experience with the solar folks at Tesla was quite good. Make sure to use someone's (or your own!) referral code if you do move forward, as they're offering 2k Supercharger miles.
Tesla's site shows their 'large' system in FL at $30k before incentives, $21k after. That's for an 11.4 kW system producing on average about 45 kWh/day--well under $2/W after tax credit. I think you'd want a system a bit bigger than that if you want to zero out your usage. Even tho Tesla offers those three sizes on their site, they will work with you if you want or need something a bit bigger or smaller than any given tier. (The tiers are 12/24/36 panels, and I just had 15 installed last month, for example.)
Also keep in mind that barring any speedy action by the federal government, the ITC that grants the 30% federal tax credit on panel installs begins to sunset on 1/1/20, so if you are going to make the move to solar, doing so this year makes sense.
Good luck, whatever you decide.