the "traditional" way of using multiple sols is a bit strange tbh................... in practise it works (starting with 2 at 24v and adding another as you go up 12v at a time)
but, really in theory adding them in series shouldn't make any difference to the load they can carry (putting them in paralell would cut the load each one sees)
The biggest advantage is that (with them in paralell) if one sticks you dont get a fire! Every one in a string needs to stick first. You do need to check them regularly with a meter to find stuck ones and replace them tho.....................
Ideally you need 3 accurates (or accumaxes) ina string for each pump. I wouldn't use odd ones in a system.