Car forums are full of complaints about 12v batteries on hybrids discharging and not having enough capacity for the electronics to start the main systems. I have had to call for help on a couple of occasions and now carry a booster. I can't really expect my elderly wife to start lifting the bonnet and connecting up the booster. I also don't like leaving the car in "ready" mode for an hour each week to charge the battery as suggested by the manufacturer.
What is your advice on small solar panels, such as sold by the AA, on the dashboard connected to the OBD? Is this safe and effective? Can I leave the connector in place in the OBD socket and just break the connection nearer the panel for convenience before driving?