Which is more efficient? Turn on 1 FCU or turning on 2 FCU in 1 system.

If you have 2 sets of A Scenario running, you will consume 1.18kW at the start vs B Scenario which consume about 1.28kW. However, in A Scenario, the minimum power consumption will be 0.9kW vs B scenario which is only 0.6kW

Most of the time, the unit will run lower than rated power consumption in the evening and night-time, thus Scenario B in the long run will have better cost savings!