Tom, as far as I know you can hook and should hook them in parallel to increase your input/output capacity. They are designed to be run slightly higher then their ratings, so I don't see a problem. The c60's I believe could handle 12/24/48 at 60amps each. The inputs would go to both controllers equally in parallel, and the outputs could be either separated "one as diversion load" and one as "batt charge" as far as I am aware without problems (set limits), you could also hook both outputs as diversion loads in parallel. Provided both units are fed the exact same input. I don't see a phase problem. Lets see what others say on this.