Instead of hunting for electrical outlets to power up my laptop on the road, I'd love to have my own power source. The Voltaic backpack has three solar panels that can generate as much as 4 watts of power, which is plenty. There are 11 adapters, plus built-in pouches for charging devices and slots for storing excess wires. What if it was overcast and my bag was sapped of energy? No problem: It can also be juiced with a car charger.