I just finished a long solo expedition and I used the Scotty Sea Light. It works really well and uses two AA batteries.
The best solar charger is the Solio (make sure you get the right model for your needs). I actually run two different models for all of my electronics. One interesting option are the special AA batteries which can easily be recharged with this unit. Also many other light attachments can be used with the unit.
Be careful at night, especially when in shipping lanes. No music should be played and keep your wits about you on long night crossings.