Self-contained, All-in-one, or Custom-made electrical systems?
In the very basic and rudimentary form, an electrical system needs to have a battery, a way to charge that battery, and a way to tap into the battery to draw power and use it for other devices or uses.
If we look at a mobile power bank (the small handheld ones, for mobile phones), then we can see exactly that – a device that can charge off of any available USB socket, store a certain capacity inside its battery, and then deliver that power back when needed, again using the USB outlet. In between, it has to regulate the voltage and current while charging and discharging, it has to make sure the batteries stay within a set of parameters, and it usually has a main on-off switch and a basic display of battery level. all of it is contained inside a premade package, the user never has to design, choose, or handle it in any way – it just works, out of the box.
In much of the same way, there are “Boxes” that do and handle everything inside, at much larger scales. These boxes are also essentially big batteries, with a way to charge them and a way to tap into them and power other devices in the van. In our camper van use scenario we can expect to have 12V charging and 12V outlet at the very minimum, with many such boxes also capable of charging off the grid, charging off of a solar panel, having a built-in power inverter delivering 110/220V AC output, various display or gauges and some even with Bluetooth or wifi connectivity for monitoring/set-up via mobile phone.
Since boxes are designed as a complete system, you are assured that all of the components housed within them are sized correctly, that they are built to the appropriate code/standard and that they are space/weight-optimized. For smaller builds, car camping, Minivans, and smaller vans without power-hungry devices, they will usually prove to be the most efficient, although they might appear more expensive at first glance.
In some cases, it is also possible to use a self-contained box, along with another battery box from the same brand, in a matched system, doubling the capacity (or more).
When scaling up, for larger vans, when using electricity as the sole power source for space-heating, water-heating, and cooking (as opposed to propane or diesel for instance), then going for an all-in-one charger-inverter solution makes better sense, especially when paired with a 48V battery.
These all-in-ones are a cost-effective way to get all of the usability that we can expect when living in a van, without too much of a sacrifice. You will usually find an inverter capable of at least 3KW, meaning that you can run just about any household appliance, you will most likely find a solar charge controller (MPPT) with a capacity far greater than what you could place on the roof of a van, you will find at least some level of app connectivity, allowing you to get a current status, error reporting, and system maintenance.
In some cases, you may find that your use case is a bit different and will need a certain component that is different. One possible case is when using a fairly small solar panel (in residential terms), and having a voltage too low for the built-in MPPT to work properly.
Another scenario could be when using an extremely power-hungry device, like a winch on a 4×4 vehicle, and needing a specialized connection capable of safely handling that load.
In all these cases, it is always possible to tailor an exact combination of discrete devices, and they can all be made to match and communicate with one another, but it does require planning, and sizing accordingly, and will usually prove to be a more costly option.
Below is a list of leading brands and products in each segment. It is not a complete list and they are not ranked by any particular order, it is simply here to guide you as to what is available and help you narrow down your search.