I really like your nice and compact setup, but please keep in mind that there’s quite some energy stored in the battery which it can unleash into any conductor that touches the terminals. This might be you sitting something on the window edge, or some conductive plastic (think: metallized plastic foil) being swept around by wind.
So, instead of the clamps shown in the picture, please think about a proper termination of the cables to the battery (screws and a cable lug) and adding an inline fuse holder. And then add insulating covers (heat-shrink tubing with cutouts, and I’m sure there are commercial products).
This greatly reduces the possibility that any mishap results in unpleasant consequences.
That aside, I really like the idea of researching ones own power consumption and exploring how self-sufficient one can live regarding electrical energy!