The BigBlue SolarPowa 28W stays the most rational portable solar charger for anyone who just wants a phone kept charged without weighing the pack down. Why not just grab a more powerful panel while you’re at it? Because weight, charging speed, and waterproofing often pull in opposite directions, and every model in this comparison makes a different trade-off. The Anker Solix PS30 bets on fast USB-C for anyone who also wants to charge a power bank or a tablet. The FlexSolar 40W shifts the logic entirely with the highest power and the best waterproofing of the three, at the cost of extra weight.
- The lightest: BigBlue SolarPowa 28W, around 680 g, the best weight-to-price ratio for a phone
- The fastest over USB-C: Anker Solix PS30, up to 30 W, compatible with modern fast charging
- The most powerful and waterproof: FlexSolar 40W, IP67 rated, with a DC output for power stations
Contents
- Portable solar charger, the comparison at a glance
- Rated power versus actual power in the sun
- Weight and folding, what matters on the trail
- Output ports, matching your gear
- BigBlue SolarPowa 28W
- Anker Solix PS30
- FlexSolar 40W
- Getting the angle right, the move that changes everything
- Clouds and weather, the real impact on output
- Upkeep and storage, making it last
- Questions that come up most often
- Which model to grab based on how you travel
Portable solar charger, the comparison at a glance
Three solar chargers, three different uses. Here’s the essential rundown before digging into each model.
| Model | Power | Weight | Profile |
|---|---|---|---|
| BigBlue SolarPowa 28W | 28 W rated | ~680 g | Light, phone and small devices |
| Anker Solix PS30 | 30 W rated | ~1.09 kg | Fast USB-C, tablet and power bank |
| FlexSolar 40W | 40 W rated | ~1.3 kg | IP67, DC output for power stations |
Rated power versus actual power in the sun
The BigBlue SolarPowa 28W is rated at 28 W but in practice delivers enough to charge a smartphone from 0 to 50% in about 45 minutes under optimal full-sun conditions, a number that drops fast the moment a cloud passes or the angle isn’t quite right. The Anker Solix PS30, rated at 30 W, actually runs closer to 20-24 W in real-world use according to the tests reviewed, a gap that stays within the norm for this type of foldable panel.
The FlexSolar 40W posts the highest rated power of the three, but that power splits between its USB-C port (up to 40 W) and its USB-A port (capped at 18 W): no single device can actually pull the full 40 W, a nuance the headline number never shows. This gap between rated and actual power hits every foldable solar panel without exception: manufacturer numbers get measured in a lab, under sunlight conditions rarely reproduced on an actual trail.
More articles on WildSurvival
- Recognizing Acute Mountain Sickness Before It Gets Worse
- Bushcraft Axe, Which One to Choose for Chopping, Splitting and Building
- Building an Improvised Water Filter From Natural Materials
Weight and folding, what matters on the trail
The BigBlue SolarPowa 28W weighs around 680 g, noticeably less than the Anker Solix PS30 (around 1.09 kg) and the FlexSolar 40W (around 1.3 kg, the heaviest of the three). Much of that extra weight on the FlexSolar comes from its ETFE coating, more resistant to abrasion and UV than a standard PET coating, but also denser.
On waterproofing, the three models line up in a clear order: the FlexSolar 40W carries an IP67 rating (survives brief submersion), the Anker Solix PS30 an IP65 rating (protected against water jets), and the BigBlue SolarPowa 28W an IP44 rating (protected against splashes). The higher the number after “IP” climbs, the more serious the water protection, a detail worth knowing before heading out under unpredictable weather.
Output ports, matching your gear
The Anker Solix PS30 stands out with its 15 W USB-C port (5V/3A) alongside a 12 W USB-A port (5V/2.4A), coverage that handles nearly every recent smartphone and power bank without an extra adapter. The BigBlue SolarPowa 28W sticks to a more generalist output, enough for a phone but less optimized for devices built to take advantage of USB-C fast charging.
The FlexSolar 40W takes a different route with a USB-C port rated up to 40 W, a QC3.0 fast-charge USB-A port up to 18 W, and above all a 5.5mm DC output that charges a portable power station directly rather than just a phone. That DC output makes it the only one of the three built specifically for van life or a fixed bivouac where a large battery needs topping up.
BigBlue SolarPowa 28W
The BigBlue SolarPowa 28W stays the obvious pick for anyone who just wants their phone charged on a multi-day trek without weighing down the pack. Its compact folding format makes it a reliable companion clipped to the outside of a backpack while walking, soaking up sun with no extra handling.
Its limit stays its more modest output and its lighter IP44 rating compared to the other two, which struggles to power hungrier devices like a tablet in a reasonable time. For a use case centered on a phone and maybe a rechargeable headlamp, it remains an easy recommendation.
Anker Solix PS30
The Anker Solix PS30 targets hikers carrying several electronic devices (phone, power bank, camera) who want fast charging without plugging into an outlet. Its USB-C port delivers a fixed 15 W, a real speed gain over a standard USB-A output even without variable Power Delivery support.
Its heavier weight compared to the BigBlue is the trade-off worth accepting for that versatility: a sound choice for van life or a fixed bivouac, less obvious for a fast-moving multi-day hike where every gram counts. Paired with a compact portable power station, it rounds out a full charging system for a van or an extended bivouac.
FlexSolar 40W
The FlexSolar 40W targets a more demanding use case: its IP67 rating tolerates brief submersion, its ETFE coating shrugs off abrasion and UV better than a standard panel, and its 5.5mm DC output charges a portable power station directly on top of the usual USB devices. The monocrystalline cells, rated around 24% efficiency, also make it one of the more efficient panels in its class.
The trade-off for that ruggedness: a heavier build than the other two models, and several user reports flag internal wiring wear at the fold points over time, worth keeping an eye on. Our portable solar panel for camping guide covers how this more powerful type of panel fits into a full van or fixed-bivouac power setup.
Getting the angle right, the move that changes everything
A solar panel angled perpendicular to the sun’s rays produces noticeably more than one laid flat on the ground, a gap that can easily double output depending on the time of day. Re-angling the panel every hour or two, rather than setting it once in the morning and forgetting it, keeps that rough perpendicularity going all day for a few seconds of effort each time.
Laying the panel on the ground rather than clipping it to a backpack while walking is almost always more efficient, even though it means the panel sits idle during a break instead of charging continuously while moving. The trade-off mostly depends on the trip’s rhythm: continuous multi-day walking versus stages with long breaks in the sun.
Partial shade hurts a foldable solar panel far more than people expect: a single shaded cell out of the fifteen or twenty that make up the panel can drop the whole panel’s output by far more than its share of the surface covered, an effect tied to the cells being wired in series. Checking that no branch, strap, or bag corner casts a shadow on any part of the panel before leaving it to charge avoids this disproportionate loss of output.
Clouds and weather, the real impact on output
A hazy or partly cloudy sky cuts a solar panel’s output by 50 to 80% compared to direct full sun, a drop that often surprises users used to thinking in all-or-nothing terms (sun or no charge at all). A fully overcast sky doesn’t drop output to zero either: some small output stays possible, just not enough for a fast charge.
Planning for unpredictable weather by carrying a standard power bank as backup, charged before departure, avoids relying solely on the day’s sunlight to keep a phone running. Our guide to reading the weather without an app also helps anticipate the days when solar clearly won’t be a dependable option.
Upkeep and storage, making it last
Wiping the cell surface with a soft, dry cloth after a dusty or sandy trip prevents a thin layer of grime from gradually cutting into output, a buildup that often goes unnoticed since it happens so slowly. Letting a panel that got caught in the rain dry completely before folding and storing it also prevents mold from forming at the joints between cells, a common weak point on budget foldable models.
Storing the panel flat rather than rolled up tight, when space allows, reduces wear on the folding hinges over the long run, a particular point of vigilance on the FlexSolar given its identified fold-point wiring weakness. A USB port that seems to charge more and more slowly over the months often points to oxidized contacts rather than a failure of the panel itself: a light cleaning with isopropyl alcohol on the pins usually restores the original charging power. A GPS watch like the ones covered in our Garmin Fenix 8 review benefits directly from this kind of charger on an extended bivouac too, its battery topping up just as well as a phone on the same USB port.
Questions that come up most often
Can a portable solar charger charge a smartphone directly with no battery in between?
Yes, all three models charge a phone directly through their USB port, but charging stops with every passing cloud or angle change. Using a power bank as a buffer gives a steadier charge, without interruptions tied to changing sunlight.
Does a portable solar panel work through a window or windshield?
Output drops sharply through glass, which filters out part of the light spectrum the photovoltaic cells need. Setting the panel outside for even a few minutes beats an entire day behind a window by a wide margin.
Does a portable solar charger need protecting from rain?
The FlexSolar 40W (IP67) and the Anker Solix PS30 (IP65) tolerate more water exposure than the BigBlue (IP44). As a precaution, stowing any of the three models away during heavy rain remains the safest habit, since the USB ports stay the weak point against moisture.
How long does a portable solar charger last before losing efficiency?
Quality photovoltaic cells typically lose less than 20% of their output after about ten years of regular use. Repeated folding, more than wear on the cells themselves, remains the most common cause of early degradation on a foldable model.
Which model to grab based on how you travel
| The lightest | BigBlue SolarPowa 28W, for keeping a phone charged without weighing down the pack |
| The fastest over USB-C | Anker Solix PS30, for several devices and modern fast charging |
| The most powerful and waterproof | FlexSolar 40W, for topping up a power station in a van or fixed bivouac |
The choice mostly comes down to what you’re actually charging and how you travel. For a multi-day hike where only the phone matters, the BigBlue SolarPowa 28W stays the most rational pick. For van life or a fixed bivouac with several devices to charge, the Anker Solix PS30 justifies its extra weight through sheer versatility. And for anyone who needs to top up a large power bank or a power station rather than just a phone, the FlexSolar 40W combines the highest power and the toughest waterproofing of the three. In all three cases, our 72-hour survival kit guide covers where solar power fits into a gear list already built for self-sufficiency.
This article contains affiliate links.