Efficiency of electrical circuit
Generally speaking, one larger electrical machine will be cheaper and more efficient than N smaller electrical machines when running at full load.

However, there are many more considerations that might tip the balance in favour of several smaller machines. Flexibility, and efficiency at part load, you can just use one or two. Redundancy, a single failure won't take you completely offline. Installation space, you might be able to reuse small amounts of space rather than build a new room or foundation. Installation growth, spend money in smaller installments.

Specifically with solar installations, if groups of panels face in different directions, then it's more efficient to run each direction into its own MPPT inverter.