We’re often asked about wiring a solar panel to a battery and charge controller for an off-grid compost toilet (to run the fan or some LED lighting).
UK solar experts AKT solar have produced a handy little video that shows you the basics. Charge controllers can be slightly different from the one shown, but all have the same basic connections – usually a input pair (from solar panel), battery pair and load (ie items that need power) pair.
The most important thing with 12V DC solar is ensuring you always maintain the correct polarity, i.e. that positive wires go to positive connectors and so on.