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Here it says that for an off-grid system the minimal configuration is 3 battery modules (12 KWh), while for on-grid it is 1 module. Is there a technical reason for that, or is it "just" a safety measure to ensure enough reserve capacity?
Actually, I would like to use two modules in my off-grid system and my only load is a car battery, which is only charged, when there is sufficient energy, so there is no permanent load, which has to be sustained.
The battery is sized for inverter capacity (after that it is sized for storage size to sustain loads). It is sized this way so the inverter is able to draw full current needed in order to shutdown safely in the event of for example a short circuir in the wiring. It also needs to be a good size to sink extra current from overshoot in solar production say for example if a larger load were to suddenly disconnect.
There is a small note further down that descrives "with inrush" and what that means.
If you don't need battery capacity for back up and you have much lower loads, buy a smaller inverter.
Define car battery - 12v guy in engine bay or an actual EV? I assume you mean EV. For a reliable system use the min recommendation or more if your install needs, otherwise there could be a dead inverter battery after a very short service life or worse a fire.
The Smart Solar is nearly perfect for me (3KWp solar), and I intended to have 3 modules anyway, but from a storage perspective I do not really need it, and of course, price, weight, and size are a factor. Maybe you could build a Smart Solar 5000..;-)
