Since info is kind of sketchy, let me tell you what I have and what it does from there. I have 4- 305 watt panels with a 40 amp solar controller. The controller is rated at 40 amps and a max of 150 volts. Anything over 1050 watts, per controller specs, will not be used or is wasted. Even though I should be getting 1220 watts at best sunlight and coolest part of the year, I have only been in the range of 600 to 900 watts at best times. I say this to let you know age of panels, shading, angle of the sun, etc, will all effect watt production and you will probably never see the same wattage that you add up from your panel array vs actual production. I average 4 to 5 KW per day of used /stored DC current. Some solar controllers like mine can be over paneled. I am running a 24 volt setup. With my controller it is rated at 150 volts and a max production wattage of 1050 but it can be over paneled up to 3000 watts. When you over panel, you will collect more energy in inefficient times of the day but the in the best times of the day it will only produce 1050 max charging wattage.
Without knowing the specs on your controller we will not be able to know how many panels can actually be attached so you will need to find that info.
As far as up grading as you go that is a good idea but bear in mind that as you add new batteries to old batteries systems, they may not play well together depending the span of life between them. LPO4 you can add up to a year apart and still be ok where Flooded or AGM batteries will need to be keep closer together as far as percentage of life left.
I know this is different that you have now but it will kinda give you some info to chew on. And oh by they way, I am an old fart too.