Manual j is required to determine the load on the structure. You can get manual j and do it long hand or get software (not sure how detailed you need to be in your area-there are easy programs and detailed ones). Manual s is equipment selection to handle the load determined in manual J. Doesn't matter if it revs up and down as long as it covers the max. load.
Give a man a fish, he will eat for a day. Teach a man to fish, he will eat for a lifetime.
Give a man a capacitor, doesn't know what to do. Teach a man to install it, now he knows everything.