Re: Solar phone/tablet chargers
Keep the extra radios (wifi, bt, gps) turned off and the phone will last much longer. Unless you've been conned into an iphone or the few smartphones that are also user-proof, you can simply buy a couple of extra batteries and throw them in as needed.
Or buy one of the pocket chargers, that either use one or two AA cells to give your phone a 1-shot full recharge, some are only "lipstick" sized and recharge from any USB port or charger. There are also larger USB chargers for phones, basically a large rechargeable battery.
Yes, to last "forever" you need solar and the key there is that you need to either leave your phone on deck in the sun (oops) or get a solar charger with battery built in, so you recharge it and then transfer the power ot the phone. How well it works is all in the numbers, if it makes enough amp-hours to charge your phone battery, or not.