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After new testing, we’re making the Allpowers SP012 Portable Solar Panel 100W our top pick and the BigBlue 28W USB Solar Charger our budget pick. We’ll update this guide with more details soon. Shock Absorber Body Harness
Unlike the finite energy stored in a battery pack, a USB solar charger offers a tiny power plant that can generate power for your phone and small electronics to keep them charged when the sun is out—you can even use one to recharge a power bank and save that energy for later. After spending more than 60 hours testing 12 models, we’re confident that the BigBlue 28W USB Solar Charger is the best portable solar charger for people who need to charge their gadgets and stay connected in an emergency or when they’re off the grid.
This lightweight solar charger gives you the most usable power for the size. Plus, it has three output ports to charge more devices than the competition can at the same time.
The BigBlue 28W USB Solar Charger produces the most power of any portable solar charger we’ve tested, and it has unique features that make it more versatile and durable, including three output ports (versus two on most other chargers), a weatherproof port protector, and an expansive but lightweight array of panels to catch every last ray of sunlight. Although other models come close to matching it in terms of power, the BigBlue is also smaller and lighter than other options with similar output, so it can more easily fit into a camping backpack, hiking daypack, or emergency kit.
I’ve been a science journalist for nearly a decade, covering a wide variety of topics from particle physics to satellite remote sensing. Since joining Wirecutter in 2017, I’ve reported on surge protectors, portable power stations, home EV chargers, and more. For this guide alone, I’ve spent more than 30 hours cumulatively researching and testing portable solar chargers for this guide (on top of the 30 hours that other Wirecutter staffers clocked in previous years). Plus, during a month-long visit to rural Malawi, I got firsthand experience with a subpar portable solar charger—it was so slow that I gave up on it midway through the trip.
USB solar chargers are a great option if you’re taking an extended camping trip or if you’re traveling somewhere with an unreliable power grid. They’re also good for stashing in an emergency kit. In all those specific situations, a solar charger could charge a phone the size of an iPhone X using a few hours of midday sun. But in most situations, a USB solar charger isn’t actually the best portable power source, and you may be better off starting with a USB power bank designed for phones and tablets, USB-C laptops, or AC-powered laptops. Our power bank picks keep a smartphone charged for hours or even days at a time, are the size of a paperback novel or smaller, and are not dependent on the weather.
But whether you choose a solar charger or a battery, it’ll work only with USB or USB-C devices, which limits these options’ appeal for anyone who needs power for a long-term, off-grid setup. If you’re going to be mostly stationary and need to charge or run larger devices like laptops or televisions, or if you need to use more sophisticated communications equipment, you’ll probably be more interested in the larger setups that we cover in our guide to the best portable power stations.
To decide which solar chargers we wanted to test, we started with a pool culled from Amazon’s best-selling and top-reviewed listings, recommendations from authoritative review sites such as OutdoorGearLab, and any mentions on sites that specialize in tech or outdoor gear. Bad overall ratings or poor owner-review scores on Fakespot weren’t automatic dealbreakers, but we did axe any models with a pattern of bad reviews—those mentioning problems such as inconsistent and slow performance, warping and bowing, or power-related problems and defects. Before calling in any models for testing, we considered these key features:
We considered only USB solar chargers rated at 10 watts or higher because with anything less you may not get enough power throughout the day to charge a single phone, which just isn’t practical. Although we preferred models that claimed to offer even more power, we didn’t want that to come with a major increase in size that would limit the charger’s portability.
We skipped any chargers that had only a single USB charging port. We preferred two output ports, a design that lets you charge a second device or share the power with someone else. Any extra ports were a bonus. Each port had to draw at least 1 amp, which is the minimum necessary to fully charge a phone like the iPhone X in three to four hours.
A good portable solar charger is sized such that you can easily fold it up and stow it away in a daypack—ideally it should not be much bigger than an iPad. At the same time, more surface area is better at capturing elusive rays on a cloudy day, so we discounted models with fewer than two panels. (In previous tests, we saw poor results from small, brick-style models with a built-in battery.) And since backpackers or hike-in campers are the most likely people to need a solar charger, we didn’t want it to add too much weight to a pack. Every model we tested weighed around a pound, and we didn’t consider anything over 2 pounds.
We looked at the company websites and contacted customer support to make sure each model was made and distributed by a reputable brand, was readily available to buy, was unlikely to go out of stock quickly, and was under warranty for at least a year.
If a charger came with any bonus features, we took those into account as well. Features such as a magnetic closure or a built-in kickstand can make a solar charger easier to use, but only if it’s already great at its core job of producing power and charging devices. Most of the chargers we tested included a USB–to–Micro-USB cable, but some (like Anker’s 3-foot cable) were longer or felt more durable than others. Many included a few carabiners, too. The carabiners themselves were small and chintzy across the board, but we appreciated the added ability to hang the charger from a backpack or tent.
Solar chargers that cost more than $100 either don’t offer any notable advantages over sub-$100 models or occupy a completely different size and weight class that would be overkill for the casual camper or the average emergency kit. On the other end of the scale, really inexpensive solar chargers generally can’t produce enough power or charge fast enough to be worth bothering with.
That left us with just four chargers that hit our sweet spot of maximum-output rating, size and weight, availability, and nice-to-have features for our most recent round of testing in 2021. We tested the Anker 15W PowerPort Solar Lite (our former top pick, now discontinued) against three competitors:
We tested the most promising models on a smoggy July week in New York City. If you’re planning to travel closer to the equator or under clearer skies, you’ll get more power than we did in our testing. But since we’ve tested chargers under ideal conditions in the past—in sunny Southern California—this time we wanted to have a point of comparison for the benefit of urban dwellers a bit farther north. We conducted head-to-head tests to make sure each charger had the same weather conditions, and we measured each model’s maximum power output, the total power it produced throughout the day, and how consistent the power production was when the charger was faced with passing clouds.
This lightweight solar charger gives you the most usable power for the size. Plus, it has three output ports to charge more devices than the competition can at the same time.
The BigBlue 28W USB Solar Charger is the USB solar charger we’d pack for a week in the woods or a month in Malawi. It produces the most power of the models we tested and offers several standout features—an additional output port, a weatherproof port protector, and an expansive (but lightweight) array of panels to catch every last ray of sunlight.
At the sunniest point of our tests, the BigBlue produced as much power as any model we tested, reaching about 10.7 watts. Plus, over the course of the day, it had the highest cumulative wattage: 48.8 watt-hours.
The BigBlue stood out among the dozens of models we considered in part because it has two 2.4 A ports and one 1 A port so you can charge three devices simultaneously. (Those ratings are based on the assumption that the solar panels are working at full 28-watt capacity, which will rarely happen with any solar charger.) Every other model we tested had just two ports.
Plus, the ports on the BigBlue are the most protected from water and dust among all the models we tested, as they’re covered by both a cloth flap and a rubber cover. Thankfully the cover is connected by a small tether so you don’t lose it.
The BigBlue looks attractive, feels sturdy, and is well made with a weatherproof synthetic fabric. It’s one of the lightest models we tested—at 1 pound, 4 ounces, it’s about as heavy as a can of soup—and when folded up it measures just 11.1 by 6.3 by 1.3 inches. When unfolded, it’s by far the largest model we tested, with four solar panels for catching every possible ray on a cloudy day.
To power your gear, the BigBlue charger comes with a 2-foot cable. That’s relatively short, but it should still be long enough to place your power bank safely in the shade while leaving your solar panels exposed to the sun. Also included are four carabiners—they clip onto the fabric loops sewn around the edges of the BigBlue—that you can use to attach it to the outside of a backpack for on-the-go powering or to a tent to charge up your gear while you’re enjoying the day.
The main downside of the BigBlue charger is, as the brand name might suggest, its size. When unfolded, it’s longer than most models we tested, making it a little harder to maneuver into just the right position. But the extra size gives it more surface area to collect the sunshine, and it’s still relatively sleek and compact when packed—that’s when size and weight are most important.
Some models we’ve tested snap closed with two magnets sewn into the material—making them, quite literally, a snap to pack up and stow away. The BigBlue’s single strip of Velcro was on the wimpier side, and came unstuck more easily. We’ve noticed in past long-term testing that Velcro generally wears poorly in water, mud, and sun in comparison with magnets. Something to keep in mind, but again, not a dealbreaker.
One of the wonderful things about solar power is how simple it can be. The only care and maintenance most solar panels require is keeping them relatively clean and free of dust. A damp cloth should do the trick most of the time.
To really max out your power output, you should angle the panels correctly. A good rule of thumb is that the panel’s angle, relative to flat ground, should be roughly the same as your latitude, with some minor seasonal adjustments. The farther you are from the poles—and from summer—the steeper the angle. For example, the average angle in Winnipeg would be around 41.1 degrees, while in Key West it would be around 22.1 degrees. Even if you don’t get the angle exactly right, approximating it could increase your power production by a noticeable amount. If you want to get the most juice, check sites such as Solarpaneltilt.com, or Solar Electricity Handbook’s Solar Angle Calculator to figure out the best angle before you go, take a photo of the setup on your phone, and try your best to replicate it out in the wild. Pro tip: Use a hiking boot to prop up the panels.
Like most solar chargers, the BigBlue includes a pocket on the top flap to store your device while charging. If it’s a hot day, though, that black pocket in direct sunlight is like an oven for your phone. You’d be better off putting your device underneath the panels—in the triangular gap between the ground, the prop, and the angled panel, perhaps—or shading it some other way to prevent it from overheating and shutting down.
We’re in the process of testing the following new models against our top pick:
James Bruce, Poweradd 14W Portable Solar Charger Review and Giveaway, MakeUseOf, August 20, 2014
Charles R. Landau, Optimum Tilt of Solar Panels, Solarpaneltilt.com, March 18, 2017
Smythe Richbourg, RAVPower 15W Foldable Solar Charger review, The Gadgeteer, June 1, 2015
Gaye Levy, Gear Review: RAVPower 15W Solar Charger with Dual USB Ports, Backdoor Survival, March 6, 2015
Solar Angle Calculator, Solar Electricity Handbook
Solar Panel Tilt Calculator, GoGreenSolar
Solar Radiation on a Tilted Surface, PVEducation.org
Sarah Witman has researched, tested, and reviewed all manner of products—from massage chairs and mousetraps to pencils and power banks—since joining Wirecutter in 2017. Before that, she worked as a science writer and fact checker for numerous publications, and she studied journalism at the University of Wisconsin. In her spare time, she eats as much cheese as her body will tolerate.
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Solar Panel Wirecutter is the product recommendation service from The New York Times. Our journalists combine independent research with (occasionally) over-the-top testing so you can make quick and confident buying decisions. Whether it’s finding great products or discovering helpful advice, we’ll help you get it right (the first time).