Hi NY. Solar is IMHO, the best upgrade you can do on a sailboat, along with upgraded batteries, if you anchor. I will include the pics, these are the only ones I have, but you can get the picture (so to speak). You can determine how many controllers you will need by keeping it simple and answering these questions. If all your panels are alike, and I mean the SAME, watts, voltage, etc, you can use one controller that can handle the max amps your panels can generate.. For example, my number one controller is a 30 amp MPPT Epever. I like this brand because it is has a USER function which allows you to set up for Lithium, a remote readout panel, and is great bang for the buck!. I have 4 100w flex panels. After I installed davits, I put a small panel on, which you see in the pic, but then upgraded to a 175W panel. This required another controller because of the difference. So its pretty simple if you dont make it complicated.
Edit. I dont believe your Perko switches will come into play with solar, unless your boat came with a solar Perko from the factory. Solar will bypass your boats electrical system completely. To make a simple installation, think of it this way. Panels create and pass to controller directly. Controller passes juice directly to house bank. No other wiring necessary. Unless you want to be fancy, its just that simple. Fuses included of course. They are your on/off switches.
I am no expert, just saying here is what I did after some research. The wrench turning is the easy part!