Defaults are invented: a 200 A busbar, a 200 A main and a 48 A inverter output. The 120% rule is checked as main breaker + 125% of the inverter continuous output current, against 120% of the busbar rating, as the SolarAPP+ help pages and the 2017 and 2020 NEC checklists on this page word it. Check which edition your AHJ enforces.
Design aid only. Assumes one busbar fed by the main at one end, a load-side breaker at the opposite end, and not a centre-fed panel. It does not check supply-side connections, sub-panels, batteries, power control systems or your AHJ's rules. The result is not an engineering review.