Which PV inverter ratio should I choose

DC/AC ratio refers to the output capacity of a PV system compared to the processing capacity of an inverter. It’s logical to assume a 9 kWh PV system should be paired with a 9 kWh inverter (a 1:1 ratio, or 1 ratio). A PV to inverter power ratio of 1.15 to 1.25 is considered optimal, while 1.2 is taken as the industry standard. [pdf]

Huawei PV Inverter Installation Instructions

This document describes the SUN2000-115KTL-M2, SUN2000-110KTL-M2, and SUN2000-100KTL-M2 in terms of their installation, electrical connections, commissioning, maintenance, and troubleshooting. [pdf]
[FAQS about Huawei PV Inverter Installation Instructions]