When it comes to charging our phones, plenty of options present themselves: the mains adapter is the one we’ll turn to the most, but alternatives let us pull in power from sources ranging from hand cranks to hydrogen fuel cells. Last fall we looked at one of the greenest options available, solar power, with the release of Xtorm’s GS4 Power Pack. Sporting a 1 Watt solar panel and 3000mAh battery, it might get the job done for something phone-sized, but what if you’re rocking a tablet or other power-hungry mobile device? Or what if you just want to charge your phone a [...]