A car output is going to be ~12-14Vdc and the solar panel at 24V. You do not want to connect those two together. Ideally you have some kind of switch that connects the input to the bluetti only to the solar panel or only to the car outlet, and to the car output only if it is present. You can probably use a contactor or a heavy duty relay that is 12V and connect the NC contact to the panels, NO to the car, and COM to the bluetti. Add a capacitor to dampen spikes whenever the system switches and connect the grounds together. A bjt jank, and also have to check the relay ratings / coil power usage