What happens if it’s cloudy for a week?

Three mechanisms handle it, in order.

Storage. 55 kWh of usable lithium capacity as standard, expandable in 25 kWh increments, at up to 95% depth of discharge, so the nameplate capacity is very nearly all available, rather than half of it as with a lead-acid design.

Generator backup. Where fitted, the generator starts automatically on low state of charge and stops once the battery is recharged, without site attendance. The battery management system holds the inverter’s shutdown threshold well above zero, so the system recovers rather than collapsing.

Design margin. This is the part that actually decides the outcome, and it happens before anything is installed. AS/NZS 4509.2 guides autonomy at 2 days with automatic generator control, 2–3 days with manual control, and 4–5 days for a system with no generation backup, but the number that governs is the maximum contiguous run of low-solar days at your specific site, in the worst month, at end-of-life battery capacity rather than nameplate.

Any supplier who answers “how many cloudy days?” without asking for your location and load profile is guessing. Ask what solar resource dataset they used and what year of degradation they modelled.