Re: Solar panel
It's a cool idea and I've always wondered why manufacturers never put a large solar panel in the roofs of vehicles.
I think the problem you'll run into is that you won't really have any benefit. You'd have to be listening to your radio for several hours and at a loud volume to actually need something like this. I've run my radio 2-3 hours while camping, listening to football games, and never had an issue.
Another problem is size. A 30+ watt panel is going to be around 2 sq ft, if not larger. You could get a smaller 5 watt panel, but I honestly don't think that will do you much good. You'd also have to park facing the sun for the solar panel to even be of benefit, which could be tricky and annoying at times.
As long as your battery isn't on the way out I think you'll be fine. I think the best and most convenient thing to do would be to buy one of those small battery back ups and keep it in the trunk. That way if your battery is failing you have peace of mind and can also help others!
Cupeez; LED Interior + License Plate Lights; Curt T Wiring Harness; Torklift EcoHitch; Weather Tech Floor Mats + Rain Deflectors; Kicker Speaker Upgrade