The world's most in-depth and scientific reviews of gear

Anker PowerPort 21W Review

This 21W is a compact, lightweight panel with unmatched efficiency and charging capabilities.
Anker 21W
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Price:  $90 List
Pros:  Efficient, powerful, great value for its size, lightweight
Cons:  Pocket too small to hold extra cords and accessories
Manufacturer:   Anker
By Jane Jackson ⋅ Senior Review Editor  ⋅  May 22, 2017
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  • Charge interruption recovery - 20% 8
  • Charging speed - 30% 8
  • Multiple device charging speed - 20% 9
  • Weight & Portability - 20% 7
  • Durability - 10% 8

Our Verdict

Anker Discontinued the PowerPort 21 in Spring 2018.

Touted as a high-performance machine, Anker's panels have often been among our winners, earning that spot mostly for their reliable, high-quality manufacturing. They have always produced a well-made, dependable product. This year, we went with the slightly more expensive, much more powerful Anker 21W as our Editors' Choice. This panel is a featherweight compared to the other 20W panels in our tests but holds its own among the other heavy hitters. This panel doubles the efficiency of last year's winner the Anker Powerport 15W but is somehow still lighter than the Goal Zero Nomad 7W and the Instapark Mercury 10W. A powerful panel that is lightweight to boot? Sounds too good to be true. But then we remembered that it was from Anker, so we had to give it a try. Read on to hear how Anker managed to steal the spotlight in this round of reviews.

Our Analysis and Test Results

Once again, it seems that Anker has continued to raise the bar in solar technology. The Anker 21W has all of the qualities of the previous award winner, the Anker 15W, with even more power. The extra 6W make a considerable difference in the Anker 21W's ability to recover a charge, charge multiple devices, and charge efficiently. Both of these panels have Anker's exclusive PowerIQ technology, which the company claims will replicate your device's original charging protocol to provide its fastest possible charging speed (with enough direct sunlight). This technology and the company's desire to continually improve and re-frame their design puts Anker on the cutting edge of portable solar gear. We were thrilled with the performance of the Anker 21W and felt that the extra money was worth it for the consistency this panel provides.

Performance Comparison

Charge Interruption Recovery

In this category, the Anker 21W did well, but performed quite similarly to the X-Dragon panel. When left in the sun for 30 minutes, the panel charged our battery pack up to 10%.

Then, after we shaded it and uncovered it some times, the panel reestablished a connection to the battery and resumed charging after about 5 minutes of attempting to do so. Most of the more significant models performed in this way, so our testing results were inconclusive as to which contender soared above all the rest regarding performance. What we did learn was that the Anker 21W works very well in partially sunny conditions, with high clouds or occasional small clouds passing overhead, the Anker charged on to keep power to our devices. Earning an 8 out of 10 in this metric, the Anker's performance was on par with that of the Anker PowerPort Lite 15W, Instapark Mercury 10, X-Dragon 20W, and Goal Zero Nomad 7.

Here is the Anker 21W alongside the X-Dragon 21W. The Anker 21W has more surface area of paneling than the X-Dragon  which increases its overall efficiency.
Here is the Anker 21W alongside the X-Dragon 21W. The Anker 21W has more surface area of paneling than the X-Dragon, which increases its overall efficiency.

Phone Charging Speed

The 21W from Anker came in a close second in our race to charge a 6,000 mAh external battery. It took just under 4 hours (3 hours and 40 minutes to be exact) for the panel to charge the battery from completely dead to 100%. When plugged into the wall, these batteries take about 2 hours to charge fully, so this is very efficient.

In 30 minutes, the 21W from Anker charged an iPhone 6 from 0 to 33%. This is only a hair shy of the PowerGreen 21W, which was the top contender in phone charging speed. It would be splitting hairs to say that one was vastly better than the other- and any panel you choose with a 21W maximum output will perform quite similarly. Simply put, the more surface area a model has with solar cells on it, the more power the panel will have.

Multiple Device Charging Speed

The 21W from Anker is a powerhouse when it comes to charging multiple devices. Out of all the panels capable of sustaining two devices, the Anker 21 takes the cake.

At 21W, it is the most powerful of all the panels, so it makes sense that it delivers a consistent charge to two devices at once. In ten minutes, the 21W from Anker was able to charge a single battery to 3%. Once another battery was plugged in, the panel continued charging the two batteries and even increased the first from 3% to 4%. No other competitor was able to increase the charge of the batteries during the short period. The runner-up was the PowerGreen 20W, which didn't improve the charge of the batteries, but delivered a consistent charge the whole time.

The dual USB port of the Anker 21W is protected from the elements inside the storage pocket of the panel.
The dual USB port of the Anker 21W is protected from the elements inside the storage pocket of the panel.


Again, Anker has delivered in created a durable, well-made product. Just like its lighter cousin, the Anker 15W, the 21W has the same Industrial-strength PET polymer faced solar cells surrounded by durable polyester canvas. This construction makes the Anker panels durable and able to withstand the harsh conditions found in the outdoors. They also have a 30-day return policy if you have any issues with the panel and will give you a full refund. Also, they have an 18-month warranty. The warrant is another benefit of buying from a reliable company. Anker has proven time and time again that they create well-made, durable products. The Instapark Mercury 10, Renogy E.Flex5, and Goal Zero Nomad 7 offered similar levels of durability.

Weight & Portability

The 21W from Anker is incredibly lightweight for its capabilities. Once for ounce, the panel is miles above the other 20W panels and even outdoes some of the panels of smaller capacities. Only a few panels weigh in lighter than the Anker on the scale. The Renogy 5W, Anker 15W, and the Nekteck 14W are the only three panels that outdid the 21W Anker by weight.

For being a tri-fold panel with a large surface area of cells, the 21W is small and sleek. When folded, the width is about the size of a thin book or a magazine. Surprisingly, it is no thicker than the Anker 15W, even though it has one more panel. These are some of the main reasons the 21W from Anker wins our Editors' Choice Award this year. It is not only reasonably priced, but it is lightweight, durable, and extremely portable.

The Anker 21W is almost as compact as its two-panel sibling  the Anker 15W. From this angle it is hard to tell which is which  showing how sleek the Anker 21W actually is.
The Anker 21W is almost as compact as its two-panel sibling, the Anker 15W. From this angle it is hard to tell which is which, showing how sleek the Anker 21W actually is.

Best Application

This panel is a great choice for charging multiple devices, efficient charging, and portability. It is a jack-of-all-trades. If you are willing to spend the money, this panel takes care of most charging needs with room to spare. Even on partially cloudy days, the 21W from Anker will still deliver some charge to your devices. For groups traveling together or for a single traveler who needs to have many devices charged, the 21W is a great option.

As we continued to learn throughout the testing period, the more extensive watt panels provide a bit of relief from the stress of trying to charge devices using solar technology. Since there are already so many external factors involved, like weather, cloud cover, wind, sun orientation, and time, it is nice to have the small buffer of having as many high-efficiency solar cells exposed to the sun as possible. We found that we spent less time fiddling with the orientation of panels like the 21W from Anker or the PowerGreen 20W because they were already capturing more power on their own than the smaller capacity panels were capable of, even with lots of adjustment. It was for these reasons that we were sold on the21W from Anker after a few weeks in the field.

The solar cells take up most of the surface area of the expanded panel  making the most of a small space.
The solar cells take up most of the surface area of the expanded panel, making the most of a small space.


The price of the 21W from Anker varies online, so the value depends greatly on what deal you can score. It's usually found on Amazon for anywhere between $65 and $100. Even at the higher end of that spectrum, this is an incredible product for the price, and you'll be getting a panel that will be effective for a long time. Over the years, solar panel technology has been improving and becoming more and more efficient. Technology is great for us consumers, and yet another benefit of its increasing popularity is the prices for decent products has gone down overall. That means products like the Anker 21W are more affordable, making this panel a great option at a middle-of-the-road price.


As our Editors' Choice Award winner, the Powerport 21W does it all. It is well made, light, and compact. It can also carry its weight as a charging powerhouse. It's efficient when charging one or more devices, and can recover its charge even after being shaded for a few minutes. The panel also works decently well on overcast days, whereas some of the lower wattage panels could not keep a charge going when clouds were overhead. A larger watt panel means faster charge times, less interruption, and a more stable supply of power. After trying such a large range of panels, we realized that in this case, the larger the wattage makes a big difference after all. The Anker Powerport 21W is a great all-around panel for a reasonable price, making it our Editors' Choice Award winner.

Jane Jackson