In the past, energy in remote areas was all related to calories, and how many calories we needed to keep our bodies active and active. However, as the use of personal electronic devices outdoors continues to change from ugly to ubiquitous, people are increasingly turning to keep our mobile phones alive. Calories are now sharing energy conversations with milliampere hours (mAh).
The rise of navigation applications such as Guthook, onX Backcountry and GaiaGPS has made backpacking more convenient and safer. Rechargeable headlights and camera batteries keep disposable batteries away from trash and our backpacks, helping to reduce waste. Portable speakers are perfect for keeping bears and future friends away. As our reliance on these key tools continues to increase, it is becoming increasingly important to keep them charged. Fortunately, this is not difficult or expensive. Advances in portable solar panels and battery pack technology are in parallel with our growing demand. Now you can pack all the energy you need in your pocket, or you can draw energy directly from the sun while you are moving. But how do you know if solar energy is right for you?
When I was preparing for the PCT hike in 2015, I thought about hiking with solar panels for the first time. At that time, I had been happily backpacking for many years without collecting juice directly from the sun. But the PCT is too long, I told myself. Is it really possible to recharge in the city only occasionally?
In my research, I found that carrying external battery packs instead of solar panels is a strong argument. At the time, batteries were smaller, cheaper, and lighter than decent solar panels. In addition, the battery can charge my phone anytime, anywhere, even under a tree or at night. Due to the least power consumption (only my phone is used for checking emails and blogging), I decided not to use solar energy and bought a 6,400 mAh battery. It works very well and I never lack charging. Since then, I have been tempted many times to risk buying portable solar panels. It was not until this year that I successfully resisted this urge to resurface.
When I hike the CDT in 2019, I still have some things to charge (add headlights and cameras). My mobile phone has also become an important navigation resource. Nevertheless, instead of using solar power, I upgraded the external power supply to a 10,000mAh battery pack. Even in the 7-day section of San Juan from Lake City to Pagosa Springs, Colorado, I never needed my battery power. After that transportation, it’s hard to imagine a scenario where I need to carry more power.
However, when I was about to hike to Sierra High Route (SHR), my confidence was shaken. Surprisingly, I now rely more on rechargeable electronics-mobile phones, headlights, cameras, watches and Garmin inReach. As an off-road route, I want to use my mobile phone to navigate on SHR more than ever. In addition, it is possible to spend up to 9 days between power outlets, but there is no guarantee that when I find an external battery, I will stay long enough to fully charge my external battery (approximately 8 hours of wall charging time). Combining all this with the bright Sierra sun and treeless terrain, I feel that I am stepping into ideal solar conditions. Adventure will also give me peace of mind and satisfy my curiosity about solar energy.
Yard sales after a wet night is a good time to throw away solar panels. The groundhog will say, “Wow, solar power, that’s so cool.”
Even tech-savvy hikers may be confused by the portable solar panel market. Not only are there countless specifications to choose from (panel type, wattage, robustness, size, built-in battery, weight), but no single option can deliver on its performance promise. The comments on solar panels are bleak, possibly due to the manufacturer’s excessively high expectations based on idealized results, which are almost impossible to replicate in the real world. And even if it meets the ideal conditions (bright large-angle sun, zero obstacles), it still takes several hours to accumulate the equivalent of a smartphone battery (3-6 hours using a 10 watt solar panel). In the best case, the solar charging time is close, but not more than the wall charging time. In short, charging from the sun requires patience.
A solar panel is defined by its output wattage (W). The 5, 10, and 20W models are common. More importantly, their size and weight are beyond the practical range of carrying a backpack. Any power below 5W will be an unreliable energy source. Deciding between these three options, or none at all, boils down to balancing four factors-cost, weight, size, and charging time. Intuitively, the first three increase as the wattage increases, while the latter decreases.
Generally speaking, solar output is directly related to the surface area of ​​the panel. To get more power, you need larger panels, or more panels. The 5W panel is roughly the same size as a large paperback book. Twice the 10W and four times the 20W. In order to maintain a reasonable size suitable for carrying in or on a backpack, the manufacturer connects up to three panels together, which can be folded up when not in use.
When tied to a backpack, this 21W solar panel is bulky and clumsy. Smaller panes are more suitable for this configuration.
The smaller size of the 5W and 10W models makes it easy to hang on the outside of the backpack, thereby maximizing harvest time. However, in this configuration, inconsistent panel angles and shadows will seriously affect the quality of sunlight. If you carry the panel in this way, it is expected that the charging time will be longer. For this reason, panels of this size are a good choice for hiking in exposed areas with little shade from trees or clouds.
A 20W solar panel can still be hung on the outside of the backpack, but it will restrict access to the pocket. It will also be more susceptible to damage due to its larger exposed surface area. Although this bulky size is clumsy, it makes the 20W panel more suitable for charging during limited rest periods. A large amount of energy can be absorbed by properly tilting a panel of this size to the sun for an hour every day.
Another factor to consider is where the energy will be stored. Most solar panels have zero capacity to store the electricity they generate. Instead, they must be paired with a separate external battery or the electronic device itself. However, some panels contain built-in battery storage, which is usually equivalent to a smart phone charge. There are no major advantages or disadvantages between each option. The only exception is that the storageless panel allows users to decide what capacity battery to carry, thereby providing greater flexibility. Remember, when comparing built-in and battery-less solar panels, don’t forget the weight of the extra battery.
For SHR, I purchased the Nekteck 21W solar charger. It has the wattage I am looking for, and is cheaper and lighter than similar panels. 18.3 ounces, I certainly wouldn’t call it “ultra-light”, but for a 21W output, this is a piece of cake. Because I want to hike the sobo, which severely limits the amount of sunlight that can be seen by the panel installed on the backpack, I chose a larger panel that can absorb a lot of energy while resting. The battery-free design is perfect for me because I already own one.
The performance of the solar panel itself met my expectations. During sunny lunchtime, I dropped it on the ground, pointed it towards the sun as much as possible, and inserted my external battery. Sure enough, the charge level increased, although not always enough to record battery status readings. In a pre-travel test at home, it charged my 10,000mAh battery in six hours under ideal conditions I could imagine.
Please note that there is no solar panel for me. Although the conditions for collecting solar juice are very good, it is not necessary.
So working in a group, I really like the concept of making something from nothing. I am also very satisfied with calling myself the Sunshine Harvester. However, it is questionable whether I will wear my Nekteck backpack again.
Why? I don’t need it. Even if I rely heavily on rechargeable devices, my external battery can provide all the power I need for a long trip between Bishop and Lone Pine for up to 8 days. I rarely expand the three panels, just to prove that it is reasonable to carry this damn thing.
If I need more electricity, I might bring an external battery instead of a solar panel. Double the weight of my 10,000mAh battery and it is still significantly smaller than Nekteck (13.4 ounces vs. 18.3 ounces). Don’t forget that I also need to bring at least one battery to store the electricity generated by the solar panels, plus another 5-7 ounces. In total, my solar system (solar + battery) weighs 25 ounces. For the same weight (26.8 ounces), my battery storage capacity (40,000 mAh) can be almost quadrupled. I suspect that even my increasing use of electronic products in remote areas will not approach the need for so much juice.
Just because I found that my backpack style does not require solar panels does not mean that they should be completely discounted. The bottom line is energy usage and time available for charging. The following are some scenarios where the formula hints in favor of solar panels:
High energy: Hikers with extremely high energy demands (such as videographers) may find that harvesting the sun can save a lot of weight and money by reducing the number of external batteries they must carry. With enough sunlight and sufficiently high-wattage solar panels, people can sustainably replenish what they use every day.
Long duration: If the hike is long enough, even hikers who use very little electricity will eventually need to recharge. In long-term, self-sufficient hikes, food weight is usually a more important limiting factor. However, food drops can extend the walking distance between full-service supply points. When the time between stops is measured in weeks rather than days, solar energy may be the only way out.
Many towns in Nepal use solar panels to generate electricity. However, deep in the mountains, electricity is unreliable. On long journeys, solar panels may be worth carrying.
International travel: Many worthy hikes involve destinations with unstable electricity. In these cases, bringing your own power plant may mean peace of mind in uncertainty.
Go fast: The compressed hiking schedule may limit the time spent wandering around power outlets. External batteries may need to be charged overnight, depending on their size. The only option may be to charge on the road. The solar panels on the backpack may not be harvested at maximum efficiency, but it is better than nothing.
Take your time: When mileage is not as important as a smile, a little extra weight is not important. This is especially true for hikers who post at base camp and leave most of their gear while hiking during the day.
Long-distance rafting trips are very suitable for solar panels. Weight is not a problem, there are no trees for many hours spent on the water.
Rafting: Similar to base camp, weight is not an important factor for rafters that can easily float hundreds of pounds of food and equipment for hundreds of miles. Solar panels are nothing to these water monsters. Due to the huge food carrying capacity, rafting trips can also last a long time. Solar energy may be necessary to keep electronic products fully charged.
Vegetarian in remote areas: Since I became a vegetarian, I stopped fishing, but now I can relive the good old days by fishing and basking in the sun.
Don’t care about weight: If you don’t care about packaging weight, there is no reason to be afraid of solar panels. Did you pack a chair and hammock on the same trip? You can also bring that panel.
I believe that most backpackers will not find it worth the effort to carry solar panels. A single external battery may be sufficient to charge any electronic device between stops in towns. Carrying two batteries may be a bit overkill, but it still has a weight advantage over solar panels. In addition, batteries are reliable when properly maintained, and the performance of solar panels fluctuates according to terrain and weather.
When considering whether it makes sense to use solar energy, realistically consider where you will use it. Trees and weather are the most important factors affecting performance. However, your hiking direction and style will also have an impact. For example, nobo hikers will get more sunlight on their backs, so compared to sobos, backpack-mounted panels will generate more energy. Hikers who rest multiple times throughout the day will be able to use larger panels more frequently, or panels with smaller angles, to obtain high-quality sunlight.
Using solar panels to convert sunlight into usable energy is a feasible and satisfying way to power the ever-expanding array of electronic devices we bring into remote areas. With so many panels to choose from, matching options to forecast requirements can be dizzying. Performance indicators and tracking conditions are difficult to determine.
Fortunately, in uncertainty, we do have the ultimate ability to control at least one thing-expectation. As long as we remain realistic about the power of solar energy, we can skip the frustration and focus on what is really important: extracting energy from thin air, just like plants. If uncertainty or exhaustion is unacceptable, consider bringing a (larger) battery pack. We can’t all be vegetables. Vegetables do not increase in price.
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Most importantly, Irving likes burritos. They are the reason why he wakes up, and the reason why he goes hiking. His hunger drove him to complete the PCT in 2015 and the CDT in 2019, and disperse him into the wilderness around the world. Sometimes engineers and hikers are always rubbish. He lives to experience, understand and help the earth. www.hikefordays.com