+1 that the Solio chargers are weak and slow. That was my experience on tour Summer 2008. Not really worth carrying. Construction was not very durable either. by mid-way through the tour, the three sections were loose from one another.
My impression is that unless you spend a lot of money, solar chargers aren't ready for prime time for bicycle touring applications. I'm looking forward to the options getting better and cheaper, though, no doubt.