Are Solar Panels Worth It For Backpacking?

Energy in the backcountry used to be all about calories, and how many we needed to keep our bodies alive and moving.  However, as the use of personal electronic devices in the outdoors continues to transform from unsightly to ubiquitous, increasingly the conversation turns to keeping our phones alive too.  Calories now share the energy conversation with milliamp hours (mAh).

The rise of navigation apps such as Guthook, onX Backcountry, and GaiaGPS have made backpacking more accessible and safer.  Rechargeable headlamps and camera batteries help to reduce waste by keeping single-use batteries out of the garbage and our packs.  Portable speakers are great at keeping away both bears and future friends.  As our reliance on these crucial tools continues to increase, so does the importance of keeping them all charged.  Fortunately, this need not be difficult or expensive.  Advances in portable solar panel and battery pack technology have paralleled our rising need.  It is now possible to carry all the energy you’ll want in your pocket, or to draw it directly from the sun as you go.  But how do you know if going solar is right for you?

My Decision to Go Solar

As I prepared for my 2015 PCT thru-hike, for the first time ever I considered hiking with a solar panel.  At that point, I’d been backpacking for years quite happily without gathering juice directly from the sun.  But the PCT was so long, I told myself.  Could I really make it the whole way only relying on the occasional recharge in town?

Winner: external battery

In my research, what I found was a strong argument for carrying an external battery pack instead of a solar panel.  At the time, batteries were smaller, cheaper, and lighter than decent solar panels.  Furthermore, a battery would charge my phone anywhere anytime, even under trees or at night.   With minimal electrical usage (just my phone for checking emails and writing a blog), I decided against solar and bought a 6,400mAh battery.  It worked great and I never lacked for charge.  Since then, I have been tempted many times to take the plunge and buy a portable solar panel.  Until this year, I successfully resisted this resurfacing urge.

When I hiked the CDT in 2019, I had a couple more things to charge (adding a headlamp and camera).  My phone also became an important navigational resource.  Still, rather than going solar, I upgraded my external power to a 10,000mAh battery pack instead.  Even during the 7-day section through the San Juans from Lake City to Pagosa Springs, CO, I never needed to ration my battery power.  After that haul, it was hard to imagine a scenario where I would ever need to carry more power.

Sierra High Route: ideal solar conditions

However, as I geared up to hike the Sierra High Route (SHR), my confidence wavered.  Amazingly, I rely on even more rechargeable electronics now — phone, headlamp, camera, watch, and a Garmin inReach.  As an off-trail route, I anticipated using my phone more than ever for navigation on the SHR.  Also, there was potential for spending as many as 9 days between electrical outlets, with no guarantee that I would hang around long enough to fully charge my external battery when I found one (roughly 8 hours of wall charge time).  Combining all that with bright Sierra sunshine and treeless terrain, I felt like I was stepping into ideal solar conditions.  Taking the plunge would equally give me peace of mind and satisfy my solar curiosity.

Choosing a Solar Panel

Even technologically savvy hikers, may become bewildered by the portable solar panel market.  Not only are there a myriad of specifications from which to choose (panel type, wattage, ruggedness, dimensions, built-in battery, weight), but none of the options deliver on their performance promises.  Reviews of solar panels are bleak, likely due to inflated expectations derived from manufacturers overpromising based on idealized results that are near impossible to replicate in the real world.  And even if ideal conditions are met (bright, high-angle sun with zero obstructions), it still takes many hours to accumulate charge equivalent to a smartphone battery (3-6 hours using a 10-watt solar panel).  In the best circumstances, solar charging times approach, but do not eclipse, wall charging times.  In short, charging from the sun takes patience.

It’s all about surface area

Solar panels are defined by their output wattage (W).  5, 10, and 20W models are common.  Much more than that puts their bulk and weight beyond what is practicable to carry on ones back.  Any less than 5W will be an unreliable energy source.  Deciding between those three options, or none at all, comes down to balancing four factors — cost, weight, dimensions, and charge time.  Intuitively, the first three increase with increasing wattage, while the latter decreases.

As a general rule, solar output is directly linked to panel surface area.  To get more power you need a bigger panel, or more panels.  5W panels are about the same size as a large paperback.  Double that for 10W, quadruple for 20W.  In order to keep the dimensions reasonable for carrying in or on a backpack, manufacturers link up to three panels together that can fold away when not in use.

Are you charging while hiking or sitting down?

The smaller size of 5W and 10W models make them easy to hang on the outside of a backpack, which maximizes harvest time.  However, in this configuration, inconsistent panel angle and shading severely impacts the sun quality.  Expect longer charge times if carrying a panel this way.  For this reason, panels this size are a good choice for those hiking in exposed areas where shading from trees or clouds is minimal.

A 20W solar panel can still hang on the outside of a backpack, but it will limit pocket access.  It will also be more prone to damage by virtue of having a larger exposed surface area.  This unwieldy size, while awkward, make 20W panels better for charging during breaks when time is limited.  Angling a panel of this size towards the sun appropriately for just an hour a day can soak up a significant amount of energy.

Built-in storage

Another factor to consider is where the energy will be stored.  Most solar panels have zero ability to store the power that they generate.  Instead, they must be paired with a separate external battery or to an electronic device itself.  However, there are some panels that include built-in battery storage, usually equivalent to one smartphone charge.  There are no major benefits or drawbacks between each option.  The minor exception is that the no-storage panels allow for greater flexibility by letting the user decide what capacity battery to bring along.  Just remember not to forget the weight of the extra battery when comparing built-in and no-battery solar panels.

My Solar Panel in the Backcountry

For the SHR I purchased the Nekteck 21W Solar Charger.  It had the wattage I was looking for and was cheaper and lighter than similar panels.  At 18.3oz, I would certainly not call it ‘ultralight’, but for the 21W output, it was a steal.  Because I would be hiking sobo, which severely limits the amount of sun a backpack-mounted panel will see, I opted for a larger panel that could pull significant energy during breaks.  And the no-battery design was perfect for me because I already owned one.

The solar panel itself performed as I expected.  During sunny lunches, I flopped it on the ground, pointing it towards the sun as much as possible, and plugged in my external battery.  Sure enough, the charge level increased, though not always enough to register on the battery status readout.  In a pre-trip test at home, it charged my 10,000mAh battery within six hours under as ideal conditions as I can imagine.

Will I Use It Again?

So the panel worked and I really enjoyed the concept of pulling something from nothing.  I also drew great satisfaction from calling myself a sun harvester.  However, it is doubtful that I will ever backpack with my Nekteck again.

Why?  I didn’t need it.  Even with heavy reliance on rechargeable devices, my external battery provided all the power I needed for the long, 8-day stretch between Bishop and Lone Pine.  I rarely unfurled the three panels, and only to justify carrying the darn thing.

If I ever need more power, I will probably bring one more external battery instead of the solar panel.  Doubling the weight of my 10,000mAh battery is still significantly less than that of the Nekteck (13.4oz versus 18.3oz).  And let’s not forget that I still need to bring at least one battery to store the power generated by the solar panel, another 5-7oz more.  In total, my solar system (solar + battery) weighed a whopping 25 ounces.  I could almost quadruple my battery storage (40,000mAh) for the same weight (26.8oz).  I am skeptical that even my increasing electronic usage in the backcountry will ever come close to demanding that much juice.

When Are Solar Panels Worth It?

Just because I’ve found solar panels to be unnecessary for my backpacking style doesn’t mean that they should be discounted entirely.  What it comes down to is energy usage and time available for charging.  Here are some scenarios where the equation tips in favor of solar panels:

High energy:  Hikers with extremely high energy demands, such as videographers, might find that harvesting the sun saves a lot of weight and cash by reducing the number of external batteries that they must carry.  With enough sun and a solar panel with high enough wattage, one can sustainably replenish what gets used each day.

Long duration:  Even a hiker who uses little electrical power will eventually need a top-up if they hike for long enough.  Food weight is usually a more significant limiting factor to consider during long, self-supported hikes.  However, food drops can extend the hikeable distance between full-service resupply points.  When time between stops is measured in weeks, not days, solar might be the only way to go.

International travel:  Many life-list worthy hiking trips involve travel to destinations with unreliable electricity.  In these cases, bringing your own power plant can mean peace of mind amid the uncertainty.

Going fast:  A compressed hiking schedule can limit the time available for dilly dallying near an electrical outlet.  External batteries can take all night to charge depending on their size.  The only option might be to charge on the trail.  A solar panel on the backpack might not harvest at peak efficiency, but it is better than nothing at all.

Going slow:  When the miles don’t matter as much as the smiles, a little extra weight isn’t important.  This is especially true for hikers who post up at a basecamp and leave most of their gear behind while day hiking.

Rafting:  Similar to basecampers, weight isn’t a huge factor for rafters who can float hundreds of pounds of food and gear hundreds of miles with ease.  A solar panel is nothing for these behemoths of the water.  Rafting trips can also last a very long time, enabled by the titanic food carrying capacity.  Solar might be a necessity for keeping electronics topped up.

Vegans in the backcountry:  I don’t fish anymore since I went vegan, but now I can relive the good ol’ days by fishing for sun rays.

Don’t care about weight:  If you don’t care about pack weight, there is no reason to fear a solar panel.  Do you pack out a chair and a hammock on the same trip?  May as well bring that panel too.

For everyone else (that means you, thru-hikers)

I believe that most backpackers will not find carrying a solar panel to be worth the effort.  A single external battery is likely enough to recharge any electronics between town stops.  Carrying two batteries, while likely overkill, still has a weight advantage over a solar panel.  Moreover, a battery is reliable when properly cared for whereas solar panel performance will fluctuate depending on the terrain and weather.

When considering if it makes sense to go solar, think realistically about where you will use it.  Trees and weather are the most important factors that will impact performance.  However, your hiking direction and style will have influence as well.  For example, nobo hikers will receive more sun on their backs, and thus will generate more power from backpack-mounted panels than sobos.  Hikers who take many breaks throughout the day will be able to use larger panels more frequently, or angle smaller panels for high quality sunlight.

Final Thoughts

Converting sunlight into useable energy with solar panels is a viable and satisfying way to power the expanding array of electronic gadgets that we bring into the backcountry.  With so many panels to choose from, it can be dizzying to match the options with one’s predicted requirements.  Performance metrics and trail conditions are difficult to pin down.

Fortunately, amid the uncertainty, we do have the ultimate ability to control at least one thing — expectation.  As long as we remain realistic about what solar is capable of, we can skip the frustration and concentrate on what really matters: pulling power from thin air, like a vegetable.  And if uncertainty or running out of power is unacceptable, consider bringing a (bigger) battery pack.  We can’t all be vegetables.  Vegetables don’t hike.