It is intended to improve tolerance when demand is not evenly divided across the three phases. In a real building, one phase may temporarily carry more single-phase appliances than the others. The HESP platform is specified for 150% single-phase unbalanced-load output, which gives the 3 phase hybrid inverter more flexibility than a system that expects near-perfect balance. It is not permission to ignore phase planning; panel design and load distribution should still be arranged sensibly so one phase is not continuously overloaded.
