Indeed. With a polarised breaker you always have to think: Which side is MORE positive. When it sits between a PV array and an MPPT, the positive from the PV array is more positive than the positive of the battery, so the the PV side connects as labelled, and the battery side connects straight through, but with the labeling on that side reversed (which can be confusing).
Similarly, the battery negative is MORE positive than the PV negative… so there will be a + on the battery side where the black cable connects. Confusing, but that’s how it works.
With a non-polarised breaker it doesn’t matter. I like to stick with some kind convention, eg I might place positive on the left (always), but that’s a personal choice.