Dear Thomas,
Sorry for the late reply because of Chinese Spring Festival!
For SPF 5000ES, your PV system needs to meet the requirement below:
MAX PV input voltage : 450V
MAX PV input current 18(22A, Newest firmware), if you connect more PV strings and PV input voltage doesn’t exceed 450V, even though your PV input current has exceeded 22A( Newest firmware), you don’t need to worry about that will damage inverter. SPF 5000ES will limit PV input current automatically based on MPPT algorithm.
What if you connect more PV strings, excess energy will be wasted.