I’m a little wary of plug-in solar in the US. Some of the bills propose allowing 1200 watt panels which can overload wiring depending on what else is on the circuit and how in the wall wiring is run. Limiting plug-in panel wattage to, say, 400 watts might be necessary
You are correct. Excess current could exist in portions of the circuit but never be seen by the breaker, therefore the breaker could not protect against it.