Solar Battery Charger

[Peterkin]

My Verso is being little used at the moment and there's a risk that the Battery may discharge to the point that the car won't start when I need it.

I have a solar charging panel that - in good sunlight - can deliver 0.5A, which is plenty enough to keep the Battery topped up. I'd like to put it on the dashboard (the car is parked facing south) and feed it to the Battery.

And there's the problem.

I know that the cigarette lighter socket is only connected when the ignition is on, so it's no good plugging the solar panel into it. I need to connect it directly to the battery. But I park on the street, so routing the cable through a window and into the bonnet - i.e. going outside the car - feels like asking for trouble, even though I live in a relatively low-crime area. So, is there any point inside the cabin that I could connect the panel to, or any possible route through the firewall? I don't want to remove the battery from the car if I can possibly help it.