Credit: Lyra Pierotti">

Checking out the Instapark Mercury 10 on the rocky shores of Icicle Creek, in sunny eastern Washington. This is a durable yet portable monocrystalline panel.

Until folding panels were developed, the rigid form of the monocrystalline panels could be too cumbersome to consider useful for backcountry use. Now, with rigid panels taking all kinds of useful forms, the difference is becoming moot.

The CIGS panels are typically a little less efficient than monocrystalline panels, except in low light and cloudy conditions, where the CIGS panels are purported to have a slightly higher low-light performance.

Polycrystalline

Polycrystalline panels have a bluish hue, whereas monocrystalline panels appear more black. The performance differences, however, are slightly more significant for the discerning consumer. Both types of cells are made of silicon crystals; but as the names suggest, a monocrystalline cell is made up of a single crystal ingot whereas a polycrystalline cell is made up of a growth of multiple crystal ingots. Intuitively, we are drawn to "purity" over "growths" (gross?), and it turns out that inclination holds true when buying solar panels. The monocrystalline panels, being more pure, are more efficient (22%) than polycrystalline (18%).

"By using a single cell, monocrystalline based silicon allows the electron greater freedom to move, so less energy is lost and higher efficiency is created, " explains Renogy, an American solar energy company.

For small-scale consumers, monocrystalline is the way to go. It is more expensive, but worth it for the small-time user who is less concerned about the added cost on a (relatively) cheap personal-sized solar panel. Bigger solar manufacturers may use polycrystalline panels to save money on a bulk-scale. This is reflected in the current market, with most backpacking-sized panels now using monocrystalline panels and discarding the less-durable CIGS or less efficient polycrystalline panels.

Solar Chargers vs. External Battery

In many cases you may be better served by an external battery, charged up at home or by a solar panel. An external battery the size of your smartphone will typically provide four to five full smartphone battery charges. They also store power and operate anytime of the day (not just when the sun is shining), and are usually significantly less expensive, bulky, and heavy.

If you use a power-hungry iDevice (especially iPhone 5 and newer), smartphone, or tablet, a high quality battery pack is likely the way to go. You can charge it up, stress-free, at a lower amperage, and then get several smartphone charges or a full tablet charge (or more!) out of the fully charged battery. You can also leave home with it charged up already, giving you a decent buffer against cloudy days and shady campsites.

If you will be without power for four or more days, however, a panel will likely serve you better than a battery, if you had to choose between the two. But for most weekend ventures or mountain escapes, an external battery may be the logical choice.

The ultimate solution, however, may be to pair a panel with an external battery, which is the current trend in the backpacking-sized solar market. It all comes down to what you need to power and how long you'll be without a wall socket.

Connections

All of the solar chargers we tested came equipped with USB ports; several of them, in fact, charged exclusively via USB. And most panels even provided at least one USB port with higher amperage to meet the greedy power needs of the latest model smartphones and tablets.

A close-up of the pocket to store devices, protecting them from blowing sand or snow.

While having a USB port meets the needs of most users, since smartphones and tablets charge via USB, do recognize that this doesn't mean you can charge any device when off the grid. A camera that plugs into a wall outlet, for example, will need an adapter, and a USB solar panel itself will not work. Also, any devices that need a 12-volt cigarette charging port will not work with many of these devices.

Integrated Batteries

Some solar charging devices include a battery so that you can leave your device unsupervised (save for a few angle adjustments throughout the day) in the sun for hours on end, charge up the battery, and then plug in your devices at night when you're back at camp. These solar kits are leading the charge on efficient and effective personal solar charging.