After considering 70 models and testing for over 30 hours, we determined that the Anker PowerPort Solar Lite is the best portable solar charger for people who want to power a phone or small device when in an emergency or off the grid. It can charge most phones at near-full speed and fill them with less than a day’s worth of sunlight.
The PowerPort Solar Lite is so efficient, in fact, that it’s the smallest and lightest charger we’ve tested that can produce 15 W. It’s just 18 by 11 inches when deployed and unfolded and its 11-by-6-inch dimensions when stowed are no bigger than a tablet. At 12.5 ounces, it’s lighter than one, too. You would have to spend a lot more or carry something much bigger to charge your devices more quickly. About half the chargers slowed to a crawl when a cloud passed overhead, but the Anker resumed full-speed charging almost immediately after the cloud was gone.
Solar chargers produce power that can be passed to dying gadgets, but there’s no way to store that power for later. That’s why we recommend pairing it with one of our picks for the best USB battery packs. Used together, you can take advantage of the sun during the day and recharge your devices overnight. A USB battery pack is the TiVo to your solar charger’s daytime power. In the past, we recommended an all-in-one solar panel and battery as a compromise option, but we’ve removed that recommendation. They charge too slowly and store too little energy, and they do so at too high a cost.
Honestly, a lot of people looking for a portable power solution are going to be better off skipping the solar charger altogether and starting with a USB battery pack. Our large battery pick will keep a smartphone charged every night for a week and is no bigger than a paperback novel. But if you’ll be on the trail for more than a week, you can’t be sure of your power needs, or you want something to tuck into your emergency kit, a solar charger could refill a small battery pack in a day or directly charge a smartphone in two to three hours.
The proviso is that these chargers only work with USB devices, which limits their appeal for those who need them for long-term, off-grid setups. 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 from companies like Goal Zero or even Suntactics. In the future, we may review these units, but for now, they’re outside the scope of this guide.
When it comes to anything to do with solar power, even the basics can get complicated quickly. For those who want to really understand how these chargers work and what makes one solar charger or battery different from another, read The amps and volts of electricity at the bottom of this guide. Otherwise, read on—if you get confused, you can always scroll to the end to read the explanation.
We started with a pool culled from Amazon sales and user reviews, authoritative review sites like Outdoorgearlab.com, and any mentions on sites that specialize in tech or outdoor gear. In our survey of more than 400 readers, more than 40 percent said they would want to be able to charge a tablet, so we considered only models that can produce at least 2 amps (2 A)—the minimum current required for tablets and large smartphones to charge at full (or close to full) speed. That ruled out a lot of the entry-level products in the sub-$40 range. Since 59 percent of respondents wanted to spend less than $75, we also ruled out some of the more expensive offerings. Chargers and kits with higher prices may offer more power or ports, but based on our survey, most people won’t take advantage of those more expensive, and often larger, models.
We tested five chargers in our last update: the Anker 14W Portable Solar Charger, the RAVPower 15W Solar Charger with Dual USB, the Poweradd 14W Foldable Solar Charger, the Instapark Mercury 10, and the GoalZero Nomad 7. Then, for this update, we tested the new Anker PowerPort Solar Lite directly against the top performer from the previous group, the RAVPower 15W Solar Charger with Dual USB.
The build of the Anker PowerPort Solar Lite felt similar to the rest of the chargers we’ve assessed and followed the same design philosophy. Most solar chargers are just two to four solar panels are sewn to a woven-nylon backing with any wires hidden between the layers and charging connections in a pocket at the end. You’ll find various riveted holes or loops around the edges to help you hang or mount the unit when deployed. All the models we examined had roughly the same quality of stitching and nylon, and all of them lacked any noticeable weatherproofing at the charging ports. Since the panels themselves are weatherproof, they’re just sewn in at the edges without any additional covering. The size and weight varied a little between the models, but once we had them all in hand, the basic designs didn’t vary enough that we could rule out any or pick a favorite. For solar chargers, it really comes down to performance.
With cloudless, blue Southern California skies and an expected high in the 70s, the panels were all set out at roughly a 25-degree angle at 10 a.m. and connected to a PortaPow V2 Premium USB Power Monitor and an external USB battery.
This is close to a best-case scenario in a few ways. First, even a sunny camping trip will probably yield more clouds in most parts of the world than the deserts outside Los Angeles. Second, our panels were placed at near optimal tilt. (Optimal tilt for solar panels is based on latitude and time of year.1) The biggest downside to our updated test was the weak winter sun, since we tested in November in the northern hemisphere.
In our last tests, we disqualified the top performing Poweradd charger, because once shaded it was unable to get back up to its maximum output without unplugging and reattaching the target device. That’s a dealbreaker shared by a lot of cheap solar chargers. If you decide to leave your phone and solar charger out all afternoon to absorb some juice while you’re off hiking, you’d be pretty disappointed to find your phone only charged for a total of 15 minutes before a cloud passed by. Since the RAVPower 15W charger and the Anker 14W charger were the best performers without that quirk, they became our top picks. We chose the smaller, three-panel RAVPower as our pick and the larger, four-panel Anker as our runner-up.
Because the new model from Anker, the PowerPort Solar Lite, promises the same output with just two panels, we tested it against the RAVPower for this update. In direct sunlight just after noon, the two had nearly identical production: 1.71 A for our old pick, and 1.67 A for the newcomer. But there was a huge difference when the winter sun was at a steeper angle. After 3 p.m., the larger RAVPower was still able to output 0.95 A while the Anker had effectively shut down for the day, trickling just .02 A through our measuring device.
When we discharged the test batteries that had been filling up from our solar chargers all day, the difference in available capacity was only 15 percent—3,181 mAh produced by the RAVPower and 2,705 mAh from the Anker.2 That’s a small difference for almost a pound less in your pack, and we didn’t do any midday adjustments. In this test, both panels were stationary for six hours. If you repositioned the Anker every couple hours to better capture direct light, the power production would have been even closer.
The Anker measures about 18 inches long when fully deployed—about half as long as the 31-inch RAVPower. This makes it much easier to orient towards the sun. And it has nylon loops in all four corners to hang or mount it. Folded up and ready for travel, it measures 11 by 6.3 inches and weighs just 12.5 ounces—that’s just an ounce more than an iPad mini 3. Any larger doesn’t get you enough performance to justify the size, and any smaller won’t be able to keep up with modern, power-hungry gadgets.
The PowerPort Solar Lite is still relatively new and hasn’t been reviewed by any other major review outlets, but it has 4.5 stars across 125 reviews on Amazon. If anything goes wrong, Anker offers phone support, an 18-month warranty, and a solid track record for support power accessories. We recommend that you combine it with a portable battery pack so that you can have power on demand, rain or shine, day or night.
Most solar products don’t output as much power as their marketing materials claim, and the Anker and our former runner-up pick from RAVPower are no different. Because of that, the two output ports are really aspirational more than practical. You should plan to support only one device at a useful charging speed. In fact, if you try to use both ports without direct summer sun, some newer, fast-charging hardware won’t take a charge at all.
Because the Anker has such a small surface area, it’s particularly susceptible to slower charging if it’s not aimed directly at the sun. This means that while it’s possible to charge your smartphone by leaving the panels in one spot all day, you’ll get a measurable boost if you re-aim the panels every two hours or so.
One of the wonderful things about solar power is how simple it can be. The only care and maintenance most panels require is making sure they’re relatively clean and dust free. A damp cloth should do the trick most of the time.
Like most solar chargers, the Anker 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 or otherwise in the shade to prevent it from overheating and shutting down.
The RAVPower 15W Solar Charger used to be our runner-up pick, and a great option if the Anker PowerPort Solar Lite was unavailable, but RAVPower has now discontinued this model. Although it had a three-panel design, making it twice as heavy as the Anker and more cumbersome to angle toward the sun, the larger surface area was more forgiving of less-than-ideal placement, and it caught more power in the mornings and late afternoons than our top pick. We didn’t think that the 15 percent gain was worth the extra 12 ounces in your pack, though.
Before the RAVPower 15W, the Anker 14W Dual Port Solar Charger was our runner-up. With the release of two- and three-paneled chargers, this discontinued four-panel model wasn’t much competition, even though it produced a similar amount of power in our original testing.
The Poweradd 14W (High-Efficiency) Foldable Solar Charger provided the most power in our original head-to-head testing and did so with an impressively compact and lightweight two-panel array. But after being shaded for 10 seconds and then exposed again to the sun, the unit wouldn’t bounce back to charging at its original rate. That’s a dealbreaker for anyone who’ll need to use the charger in unpredictable weather or the occasional cloud. It’s not too much to ask to simply be able to plug it in and know it’ll keep working.
While compact, Instapark’s Mercury 10 came in fourth in our power production tests and, like the Poweradd, couldn’t bounce back to full charging after being shaded.
We tested the Goal Zero Nomad 7, even though it was slightly underpowered for this guide, because Goal Zero has one of the best reputations for product quality and service in this category. The unit is well-made, features USB and DC charging options, and even has niceties like magnetic closure instead of the Velcro used on cheaper units. But at a price that’s nearly 50 percent higher for 50 percent less power, it just isn’t the best option for most people who need occasional off-grid power. For larger or more-stationary power needs, such as a research or wilderness camp, Goal Zero is one of the few companies offering quality portable solar power and AC charging for devices like laptops.
Our Nomad kit came with the company’s new Venture 30 battery, so we tested that component separately against our current travel battery pick, the Anker 2nd Gen Astro E4 13,000-mAh, to see if it offered any gains during solar charging. The Venture 30 gathered 84 percent of the power that the Astro did during our side-by-side solar charging, and we experienced some problems getting the manually activated smart charging to send the maximum current to our iPad. We contacted Goal Zero, and representatives told us that newer versions of the firmware should handle such scenarios better than our early production unit. Since the Venture 30 is part of a small class of rugged batteries, with a heavy-duty rubberized and IPX6 weatherproof housing, we’re getting a more recent build and planning to test it when we update our guide to USB batteries. In the meantime, you don’t need the Venture 30 to complete your solar-charging setup.
The Creative Edge Solar-5 all-in-one battery and solar charger tested at 2,846 mAh, which is 56.9 percent of its advertised rating. Between that and a small, slow-charging panel, it couldn’t compete with our pick.
The ZeroLemon SolarJuice 10,000-mAh all-in-one measured at 65 percent of its advertised capacity and charged as slowly as expected for a small panel. Build quality seems okay, but the casing materials are smooth plastics, slick to the point that I’d be worried about it slipping out of my hands. For some reason, the unit’s 2-A USB port was marked with one lightning bolt, while the 1-A USB port was marked with two lightning bolts.
The Poweradd Apollo 3 all-in-one tested at 63 percent of its 8,000-mAh advertised capacity but gained only 262 mAh of juice after eight hours in the sun. It also felt like it was made of cheap plastic, despite its rugged appearance.
We also considered a lot of models that could offer a lot of bang for your buck but ultimately decided against testing them for one reason or another. Most of them were eliminated for a lack of easily accessible customer support. These are typically only a few bucks cheaper, if at all, compared with similar offerings from Anker and RAVPower, which have established reputations for responsive customer support. Yet more were eliminated for not advertising enough current or being too expensive for what you get.
If you’ll be off the grid for more than a couple of days and a USB battery pack won’t keep your gadgets charged, the Anker PowerPort Solar Lite is the way to go for easy and reliable power at a good price. Pair it with our travel battery pack pick, and you’ll be set for all of your off-grid USB charging needs indefinitely.
If you want a better understanding of the principles that make solar power work, you can start with a basic primer on electricity. While this info doesn’t go into the intricacies of charging curves or the subtleties of solar charge controllers and voltage regulators, it should provide you with enough information to make more informed buying decisions.
Volts (V) measure the amount of electrical potential in your system. Probably the simplest metaphor to understand electricity is plumbing. Volts would be the equivalent of the water pressure in your house. The higher the pressure, the more power is ready to go when you turn on the tap. In the US, grid power is 120 V, but you’ll often see this referred to as 115 V or 110 V due to voltage drops over the distance to your outlets and devices. Overseas it’s often 220 V. Your car battery is 12 V, and anything drawing power from a USB port is 5 V. When electrical systems work as designed, there’s not much risk of a mismatch because the plugs generally aren’t compatible. But if you somehow managed to attach a 5 V USB device directly to the 120 V power in your wall, it’d be roughly equivalent of trying to plug a hole in a dam using a feather–but with more sparks, fire, and melting plastic. Luckily for us, USB is standardized, and the priority in any of our chargers would be to keep the voltage within an acceptable range of 5 V.
Amps (A) measure the amount of current in your system and are probably the term you see the least in daily life. A single circuit breaker in your house can probably handle 15 A or 20 A, while an RV hookup generally requires 30 A or 50 A. Your tablet probably draws around 2 A to 2.5 A. Your smartphone probably draws around 1 A. In our plumbing metaphor, amps are closest to pipe diameter. A wider pipe is going to bring a lot more water. Because we wanted our solar chargers to handle charging a tablet or battery pack more quickly, we stuck with pipes at least big enough to accommodate 2 A. (The biggest problem with the pipe analogy is that amps aren’t a physical attribute. While more amps generally require thicker wires, thicker wires doesn’t necessarily mean more amps… and water in pipes doesn’t flow back and forth at the same time at the speed of light. But anyway.)
Watts (W) are probably the most frequently mentioned unit of power. Your microwave proudly proclaims its cooking power as “1,200 watts,” your blow dryer styles your hair to perfection with 1,875 W, and you might have replaced your old 60 W incandescent bulb with our pick for a 9.5 W LED replacement. In the electrical world, volts multiplied by amps equal watts. You can just accept that as true, and you’ll always be fine. But to understand it with our plumbing metaphor, watts would be the amount of water passing through your shower head in a split second. If you have high water pressure (volts) and a really big pipe (amps), you’ll have great water flow (watts). If any one of those things is off, one or both of the others must be different, too. It also means that if you know any two of these numbers, you can figure out the third. Your 1,200 W microwave, running on household 110 V power, would be using 10.9 A because 10.9 A x 110 V = 1,200 W. And that’s why running a similarly powerful toaster at the same time can overload and trip a 15-amp breaker.
Since these three measurements are always related, and since we know we needed USB output at 5 V, and we know we wanted fast charging through at least a 2 A port, we know that the minimum panel size has to be 5 V x 2 A = 10 W. Any solar power system will have inefficiencies to bring those numbers down, but that equation tells us that no panel under 10 W has a chance at meeting our charging requirements.
But these are all instantaneous measurements, happening in a single moment. For a cumulative measurement, you can just tack on -hours. So your 60 W incandescent light bulb, running five hours a day, 30 days a month, was adding 9,000 Wh, or 9 kilowatt-hours (kWh) to your electricity bill because 5 hours x 30 days = 150 hours. 150 hours x 60 W = 9,000 Wh.
While your power bill probably comes measured in Wh or kWh, the batteries and gadgets we test with are generally measured in amp-hours (Ah) or milliamp-hours (mAh). 1 Ah = 1,000 mAh. Simplified, this means that if you plug in your phone for an hour, and it draws 1 amp the whole time, it will have charged up 1 Ah, or 1,000 mAh. If the current is low for some reason, and the phone can’t draw more than 0.5 A, then one hour will only get you 500 mAh. For comparison, the iPhone 6 battery has a 1,810-mAh capacity, while the Galaxy S5 has a 2,800-mAh battery.
With that knowledge, it’s easier to understand the relationship between solar chargers and your favorite gadget. Since most gadgets today charge off of USB, the voltage is pretty much fixed at 5 V. Depending on the gadget and battery, the manufacturer has a certain amount of amps needed to get a healthy charge in a reasonable amount of time, but not so much that it sustains damage. Your smartphone probably draws about 1 A and your tablet about 2 A. So a smartphone draws 5 V x 1 A = 5 W and your tablet draws 5 V x 2 A = 10 W. Ever try to charge your tablet on a USB power adapter made for a phone? It takes forever. That’s because your tablet wants 2 A, while the smartphone power adapter you plugged into provides only 1 A.
Where does that leave us for picking solar chargers? We know that we need our panels to produce at least 10 W in order to get a 2 A USB charge. We also know that even the most power hungry devices top out at about 2.4 A over USB, which would mean 5 V x 2.4 A=12 W. But we need to take into account acceptable power loss through inefficiencies, and low wattage due to imperfect weather conditions. So while most portable solar chargers available today use panels that generate somewhere between 5 W and 20 W, we can focus on panels between 10 W and 15 W. That wattage normally requires a couple of panels the size of a sheet of printer paper that are wired together. The more advanced (and expensive) the panel, the more power it can create in a given amount of surface area. Going higher than 20 W will cost you more money and give you more power than you can really use if you just want to charge one or two devices. But if your solar charger advertises less than 10 W, be prepared for a very slow charge that will make you feel like you wasted your money.
(Photos by Mark Smirniotis)