Backcountry Power + Charging
Modern times call for modern measures. Go ahead and 'rough it' if you wish, but technology often plays a role in our outdoor adventures these days. Bringing extra AA or AAA batteries is almost considered old school now, so grab yourself a power brick or solar panel and get to recharging with the times.

Categorize Your Adventure
Moving Around or Staying Put
How Much Do You Wish To Carry?
When looking to bring power and charging into the outdoors, you can basically put your adventure into two different categories.
1. Hiking: This would be any adventure where you're going to have to carry your gear. Whether your gear is on your back or in your canoe / kayak, or even traveling to a new city, you probably won't have a ton of space so you'll need smaller options for charging.
2. Car Camp / Base Camps: When you have a central hub or base camp, you can bring out the larger power options, as you're often bringing in gear by the car-load. Adventures are done daily and you won't have to carry around piles of gear. Charge your stuff overnight or during rest days.

Length of Time
I'll miss you.
How long will you be gone?
It's important to think about the length of time your trip will take before deciding on what type of power and / or charging to bring along with you. Shorter adventures probably don't need the whole kit and caboodle, while longer ones may need more powerful solar panels or larger power bricks to properly charge all the electronic devices that you're also bringing along. Categorize your trip length:
Day-Long or Less: Consider bringing just a small, emergency power brick. Just enough to re-charge your phone or GPS device in a pinch.
Weekend: If you're looking to go light on gear, you can still get by with a smaller emergency power brick. If you've packed more electronic devices for a bit more luxury however, consider a medium sized power brick. If you just can't live without your tablet for watching movies at night instead of the sunset, throw a small solar panel into the mix.
Week-long to Months: If you're carrying your gear for a week or longer, you can get away with a small to mid-sized power brick and small to mid-sized solar panel, but you'll probably want both items. If you're not carrying your gear and staying out for this long and have a car or boat to lug equipment, you can think about bringing a portable power station and rigid solar panel.

Harness the Power
It's gonna take a minute. Or a bunch of minutes.
Electricity vs the Sun
Your devices are experts at draining their own battery. Just remember, these little (and big) expert power suckers won't just magically regain power, it'll take some time before they're all juiced up and ready to go again. So set in for some wait times, but relax, you don't have to stare into the sun for it to work, just the solar panel does.
Solar Panel Attached to Pack: Smaller solar panels often feature attachments so you can hook 'em right to your backpack and voila! Gather that sun power as you hike to your next camp. If your solar panel didn't include hooks and loops, feel free to use that safety pin and paracord you've got hidden within your gear and MacGyver that solar panel onto your pack instead. Be aware of this method if you're in dense forest or on a cloudy day, it won't gather quite as much power as it will on a bright, clear day. Plus, you never know when the sun may reappear. IMPORTANT. When using this method, you probably need to hook up a power brick, which will store the gained power for you, even if interrupted. Solar panels DO NOT store power. Some panels allow you to charge directly to your device. Pro Tip: Read the instructions on your specific panel before use!
Sit n' Wait: Sometimes there just isn't a better way to harness some sun than sitting and waiting at camp. With this method, you can watch that solar panel soak in the sun, while you catch some rays yourself. Make sure you get a good angle and avoid all that shade. This method can allow you to charge your device directly from the solar panel. Remember to keep your device itself out of the sun, as items like smartphones don't enjoy the heat.
Pre-Charging: Don't leave home without a full charge on your device. That being said, you can also pre-charge a power brick at home via outlet, so you still have some extra power out in the backcountry. Bringing along a pre-charged power brick is a great option for short trips and weekends, as you can ditch the hassle of waiting on a solar panel.

Whatcha Chargin’?
Technology isn't very smart without power.
Make sure your charger is able to power the tech you pack
Items that need charging can be anything from smartphones, lighting / headlamps, cameras, to GPS devices, watches, and tablets. Don't forget your laptop and boom box and other non-USB devices will need some power too if you've brought them along on your trip. I could probably sit here and list a whole bunch of other stuff, but c'mon people, you know what needs charging and what doesn't. Now let's categorize those items into size:
Small: Phone, mp3 player, headlamp
Medium: Tablet, laptop, DSLR camera
Large: TV, small fridge, boom box
The reason you need to categorize your devices into size is because you'll need to know what size of solar panel and / or power brick to get. If you go with a panel / brick that is too small, it won't charge the device properly, if at all.

Sources
What Are All These Things? And which ones should I buy?
Power Up Tech Properly
SOLAR PANELS - A solar panel is how you collect the power. Open up the panel and put 'er directly in the sun. Work the angles, avoid shade and hope there won't be any clouds, tree cover or tall buildings to ruin your chances of sucking the power from the sun. You can go ahead and plug some devices in to power directly from the sun, but be aware it may not be as effective and if there is an interruption (such as a cloud layer), your device may stop charging without warning.
• Folding - Folding solar panels.... fold. They pack down small and travel well. Plus, they're lightweight
• Rigid - Rigid solar panels are quite large and don't usually fold, but do in some cases. They're a bit more durable and are meant for temporary or more permanent set up, such as outside your camper.
• Power Brick - A power brick is for storing the power. These guys can range from fitting in your fist to the palm of your hand to maybe two hands worth. Think small or medium size. The smaller ones typically offer 1 or 2 recharges of your smartphone, but won't charge larger items like a tablet. The medium ones can obviously offer more charges of your smartphone, or charge larger items like a tablet or laptop.
• Solar Kit - A kit typically includes a solar panel and a power brick. Picking them up in a bundle can save a bit of cash so you can spend the extra on a few ice creams. If you're gonna get both anyway, probably a good idea.
PORTABLE POWER STATIONS or GENERATORS - Heavy duty devices call for heavy duty power. You won't want to carry these on your back or anything, but it'll charge up all you need when you're car camping, RV-ing, on expedition (if gear is being brought in, think yaks/cars/helicopters), or even at home in an emergency situation. You can charge them via home outlet, car, or large solar panels. The best thing about these are they often include quite a few USB ports, 12V power ports, as well as AC wall outlets. Charge a whole buncha stuff, no adapter necessary. If using them at home, these are especially cool, as you can use them indoors, unlike a gas-powered generator.
Now Let's Get Charging Already!
Solar panels, power bricks and power stations are the latest and greatest when it comes to technology. Since the sun is a renewable energy, the energy you harness from it will replenish itself. I'm up for anything that'll minimize the hurt on the earth that you wish to spend time in. Plus, you get to use whichever electronic device you've charged up in return.