Power flows out on the live wire and back on the neutral. The two amounts always match. An RCBO in your fuse box quietly watches both.
If power escapes, through a damaged cable or a fault someone touches, less returns than left. The RCBO sees that gap instantly.
Sense a leak of around 30 milliamps and the RCBO snaps the circuit open in a fraction of a second. It trips on overload too, the built-in breaker doing its job.
A plug-in solar kit feeds power in through an inverter. Current can now move both ways, and the inverter is electronic, so your protection has more to handle.
A Type AC RCBO only catches smooth AC leaks. A Type A RCBO also catches pulsing DC leaks, the kind inverters and modern electronics can produce.
For a home with plug-in solar, Type A is the sensible minimum. UK wiring rules now steer away from Type AC on everyday circuits. A registered electrician confirms your setup.
Estimate what a kit could save you, then read the plain-English safety and standards guides built for UK plug-in solar.