I've redone the electrical system from last time. It's now a bit more complex, while still being pretty intuitive overall.
Basically you just have to wire stuff up. The order doesn't really matter, unless you start using splitters to section off parts of your circuit. Any circuit needs a generator and storage, and then any other equipment can pull electricity from it. You can split off parts of the circuit, which allows you to let certain pieces of equipment only pull power from certain batteries. This can act as a failsafe against high-power equipment accidentally draining all the power from, say, your oxygen systems.