Cleaning those solar panels is super important, as mentioned earlier. But one thing I've observed is that the angle of the panels can greatly impact efficiency. Adjusting the tilt to match the seasonal position of the sun can maximize sunlight exposure, thus optimizing energy conversion. A bit of work, but it pays off, believe me!
Now about rainwater collection, it's indeed a valuable resource, but as hinted before, it does come with its challenges, contamination being key among them. If you've got a filtration system, that's fantastic, but don't forget about regular cleaning of the collection area and tank – standing water can be a hotbed for bacteria.
Also, in some areas, there could be legal restrictions on rainwater collection, so a quick check with local authorities never hurts. Anyone around here ran into any legal issues with their off-grid setups?