> For lighting, it's impossible to fall back on grid power because I had to cut the power cords of all lamps to make them compatible with the 12V DC grid
Why not get a cheap-ass car battery charger? He's using lead-acid batteries anyway, and a charger for these is approx. 50 €.
Or bypass the battery entirely and use a 12V 200W power supply instead of the battery voltage (to avoid overloading your PSU with powering the equipment AND simultaneously charging the battery).
> For lighting, it's impossible to fall back on grid power because I had to cut the power cords of all lamps to make them compatible with the 12V DC grid
Why not get a cheap-ass car battery charger? He's using lead-acid batteries anyway, and a charger for these is approx. 50 €.
Or bypass the battery entirely and use a 12V 200W power supply instead of the battery voltage (to avoid overloading your PSU with powering the equipment AND simultaneously charging the battery).