Thanks for the suggestion, but I do actually have a solar charger - and it's a good one, made by Exide. It seems that my car just consumes so much current when it is left that the charger, which I had placed on the rear parcel shelf to get the maximum amount of sunshine, still could not produce enough current to keep the battery topped up (and yes it was connected directly to the battery terminals). Having wrecked two batteries in two years, it seems the only answer is for me to disconnect the battery when I leave - although that does cause its own set of problems. Apart from the fact that the alarm automatically goes off when I reconnect it, there are more things than you could imagine that are controlled by the engine management computer and which need to be manually reset or recalibrated, not just the radio but also including all the door locks, all the windows and the even seat positions.