The space used by the smallest solar charger I’ve seen on Amazon seems to be similar to 6 or more batteries in the format the N900 was taking - so if you look at space, slow charging from solar charger, and reliance on sun conditions taking individual batteries seems to be the better option for a few days hike. It’s also easier to stow individual batteries to wherever you still have space left.
The space used by the smallest solar charger I’ve seen on Amazon seems to be similar to 6 or more batteries in the format the N900 was taking - so if you look at space, slow charging from solar charger, and reliance on sun conditions taking individual batteries seems to be the better option for a few days hike. It’s also easier to stow individual batteries to wherever you still have space left.