Also a much bigger timeframe for testing and development. This isn't something you slap together in a weekend and call good. More like building an experimental drone than putting together a 3d printer kit or building a PC
No idea what you're talking about here. Solar charge controllers are quite mature and do exactly what is needed. You're literally putting a few wires on the right terminals, and a few connectors.
Only the low-battery signal would require a bit of work, but that is option and isn't found on ANY devices available off-the-shelf so it's not possible to buy your way around that.
