Use solar energy to keep a back-up power source for your tablet or phone! I have one of these myself and one good solar charge can easily charge up my iPad and still has juice to charge my phone. You can’t beat that! Groupon Goods has them for $11.99 (less than I paid… ugh), down from an original price of $99.99. Shipping will add $3.99, or it’ll ship free if you get your cart over $24.99.