Sizing with redundancy

A modular system is usually specified as N+1 or similar: enough modules to carry the load, plus one more. The frame also has to have room for the redundancy and for expected growth, otherwise the architecture delivers less than it promised.

What to establish

Present load in kW and kVA, and the power factor

Required redundancy and whether it must be maintained during maintenance

Growth expected over the life of the installation

Battery autonomy and whether batteries are internal or in a separate cabinet

Whether the modules are genuinely hot-swappable in the supplied configuration

The advantage worth paying for

The value of a modular system is not the ability to add capacity — it is the ability to service one part of the system without interrupting the load. If the configuration does not allow that, the modular premium buys very little.