Anker 21W Portable Foldable Solar Window Charger, 4-Panel

Last updated date: May 14, 2020

DWYM Score
9.5


Why Trust The DWYM Score?

DWYM is your trusted product review source. Along with our in-house experts, our team analyzes thousands of product reviews from the most trusted websites. We then create one easy-to-understand score. Learn more.

Look for the DWYM seal for products that are the best in the category.

We looked at the top Solar Window Chargers and dug through the reviews from some of the most popular review sites. Through this analysis, we've determined the best Solar Window Charger you should buy.

Overall Take

Not only does this charger fit in a backpack for hiking trips, but it's also made out of a weather-resistant canvas for camping weekends. Under direct sunlight, the solar window charger has a charging speed of up to 3 amps. In our analysis of 73 expert reviews, the Anker Anker 21W Portable Solar Window Charger, 4-Panel placed 1st when we looked at the top 10 products in the category. For the full ranking, see below.

Editor's Note May 14, 2020:
Checkout The Best Solar Window Charger for a detailed review of all the top solar window chargers.

Expert Summarized Score
9.2
12 expert reviews
User Summarized Score
8.6
2,027 user reviews
Our Favorite Video Reviews
What experts liked
Lightweight and portable thanks to its folding storage case. Charges smartphones and small electronic devices well, users report.
- BestReviews
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.
- Outdoor Gear Lab
Incorporates the fast charging technology that allows it to deliver up to 2.4 amps per USB port under direct sunlight. Moreover, the simple design of the product makes it the ideal backpack solar charger. The compact size of 11.1 x 6.3 inches and the ultra-thin design of 1.1 inches when folded, offers portability and simplicity, making it suitable for the camper or the adventurous one. Lightweight is also an important property, representing only an additional 14.7oz of weight to your backpack.
- Ecotality
The eye-hole rings are made of stainless steel and the rest of the solar charger is made of rugged polyester. The USB Port Hub is covered by the Polyester as well. When you fold the charger it does a great job at keeping the charging ports very safe and although this solar charger isn’t exactly water resistant, it does a good job at keeping water away from the main parts.
- Charger Harbor
Made up of three polymer-faced solar panels sewn into a polyester canvas material with a fourth section designed as a Velcro pocket, the entire device folds up to be about an inch thick. This makes it perfect for stashing in just about any bag that has a laptop/tablet compartment. It also turns out to fit perfectly in a small F-Stop Gear ICU right on top of everything in it. This worked out great for me since I often use this in my hiking pack.
- Fstoppers
Four metal-reinforced holes in each charger’s corners let you attach carabiner hooks to mount the opened panel, most likely on the outside of a large camping/hiking backpack; Anker lets you supply them yourself if you need them, packing in a micro-USB cable.
- 9to5Mac
The Anker is equipped with technology to identify the most effective charging conditions for devices plugged in, to offer the quickest charge without wasted energy. 1W panel set can accommodate larger or more power-hungry handheld devices, able to charge a tablet and a phone simultaneously.
- Slant
Does it all. It is well made, light, and compact. It can also carry its weight as a charging powerhouse. It’s more 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 overhead. A larger watt panel means faster charge times, less interruption, and a more stable supply of power.
- Solar Panel America
Hook this solar charger up to your backpack on your next hike and charge your phone or battery pack as you walk. The panels unfold to span about 18 inches, which is lots of surface area to capture sunshine. It can charge two devices at once and is super lightweight, weighing in at just under a pound.
- Good Housekeeping
Our top pick for the best solar charger since it offers an amazing combination of price, portability, and charging speed. Its performance leaves most of the comparable competition behind and it delivers where it counts: reliable power output.
- Outside Pursuits
Anker's solar phone charger makes it to our top three, thanks to some great reviews. Anker uses three 15W highly efficient (21.5% - 23.5%) SunPower solar panels. Weighing just 14.7oz, this solar charger is the most lightweight and compact variation in this category. So, if you want to use some of that free solar power during a camping trip without making your backpack heavier, this is your best bet.
- Solar Reviews
One of my favorite technological lifesavers. The power port is like a power bank, only this time it’s powered up by the sun, not from the electricity flowing from your wall outlet. This makes it a very versatile product. Not only does it produce power for your device when you’re on the go, it also helps you get introduced to solar panels and energy. Think green power. In addition, solar-powered portable phone charger allows you to charge two devices simultaneously because we all have more than 1 USB device.
- Not Sealed
What experts didn't like
Charges too slowly for some users, even in direct sunlight. Storage pocket in charger case can hold heat from charging devices stored there.
- BestReviews
Must be in a source of light to charge.
- Charger Harbor
Velcro pouch doesnt do much. It could come with a couple mini carabiners. Four panels might have made the amperage closer to stated specs. Removable USB hub would make it thinner for packing.
- Fstoppers
The pockets are unfortunately only large enough for an iPhone (or similarly-sized battery pack) at best, not an iPad. My personal impression is that both companies are overly optimistic about their chargers’ ability to perform in partial sunlight.
- 9to5Mac
This set of panels does not include any power storage options. This set of panels don't come with a battery, so charging will be impossible in poor weather conditions and night time. The user can overcome this by providing their own battery.
- Slant
Pocket too small to hold extra cords and accessories. Must be in a source of light to charge.
- Solar Panel America
The storage compartment design isn’t quite secure. Velcro is used rather than a zipper. Isn’t fully waterproof only water resistant. Not compatible with the iPod Nano, iPod Classic, iPod Shuffle, HP TouchPad, and some Asus tablets. Due to higher charging rates required. See below for the workaround. No other colors available. I would like white or a camo color.
- Not Sealed

From The Manufacturer

Fast Charging Technology: PowerIQ delivers the charging speed up to 2.4 amps per port or 3 amps overall under direct sunlight. 21 watt SunPower solar array is 21.5-23.5% efficient, providing enough power to charge two devices simultaneouly. Incredibly Durable: Industrial-strength PET polymer faced solar panels sewn into a rugged polyester canvas offer weather-resistant outdoor durability. Highly Portable: Compact size (11.1 × 6.3in folded or 26.4 × 11.1in opened) and stainless-steel eye-holes on each corner allow easy attachment to backpacks, trees, or tents. Lightweight and ultra-thin design make it ideal for long treks. What You Get: Anker PowerPort Solar (21W 2-Port USB Solar Charger), 3ft Micro USB cable, welcome guide, our fan-favorite 18-month warranty and friendly customer service

An Overview On Solar Window Chargers

Did you know that Albert Einstein published a paper in 1905 that helped spread awareness about the power of solar energy? Today, the benefits of switching to solar power are well known. In addition to using solar energy at home via solar panels on the roof, people can purchase portable solar window chargers to take on the go.

As you browse the available models, you want to take into consideration the number of people you have in your family. Many solar window chargers are only designed to charge one or two devices at a time. If you opt for a model like the GoerTek 25000mAh Portable Solar Window Charger, you’ll be able to charge three devices simultaneously. That’s a better choice for larger families. Of course, families can also purchase more than one solar charger if need be.

If you plan on using the solar window charger for an outdoor trip, you need to choose a model that is weather-resistant. The Hiluckey 25000mAh Outdoor Solar Window Charger, 4-Panel is not only waterproof but also dust and shockproof. It folds up and has a durable outer cover that protects the solar panels from becoming damaged when dropped.

Another important feature to look for when shopping for a solar window charger is how quickly the device charges. For example, the Anker 21W Portable Solar Window Charger, 4-Panel has the technology to charge at a speed of up to 2.4 amps when plugged into a port or 3 amps when placed in the path of direct sunlight. Some models also have a built-in eco-friendly li-polymer battery.

Review how easy the solar window charger is to transport. Ideally, you want a model that is lightweight and that can fit in a backpack or carry-on bag. Then check how the unit is designed to be used. Some models have suction cups so you can adhere them to a window, while others have stainless-steel eyeholes on each corner for hanging on the back of your pack.

Check to see if the solar window charger has any special features that put it above another model. The FEELLE 24000mAh Waterproof Solar Charger, 3-Panel is an excellent example of this, as it is outfitted with a flashlight function that has three modes. Users can set it on the steady mode for extra sight in the dark, strobe mode for adding to the party atmosphere or SOS mode when an emergency arises.

DWYM Fun Fact

Humans have been using sunlight as a source of energy for a long long time. We know that during the seventh century B.C., people used magnifying glasses to direct the sun’s rays and make it hot enough in one spot to start a fire. Later, mirrors were used in the same way as the magnifying glasses.

Edmond Becquerel was the first scientist to discover that light increased the amount of electricity in cells that had gold or platinum electrodes and that were submerged in a conducting solution. This discovery in 1839 paved the way for the solar panels we use today.

The first solar cell that resembles modern-day cells was constructed by Charles Fritz in 1883. His cell was made using selenium and wasn’t very strong, but others were able to improve upon his design over time. Aleksandr Stoletov is the first holder of a patent for a solar cell, which he obtained in 1888. It wasn’t long after this patent that solar power was commercialized.

In the 1950s and 60s, solar panels were used in a variety of spacecraft. President Jimmy Carter has solar panels installed on the roof of the White House in the 1970s. Today, solar panels are more affordable, making it possible for more homes across the globe to have them.

The Solar Window Charger Buying Guide

  • Keep in mind that you must have a source of light available in order to charge the solar window charger.
  • To keep your solar window charger powered, hang it from the outside of your backpack so that it can receive sunlight while you hike. If you’re camping, find a location that receives direct sunlight and lay the charger out. Should you be traveling in a car or sitting at home, you can place the solar charger in a window that’s facing the sun.
  • Solar windows chargers also work great when traveling via plane, train or bus. Outlets are not readily available on these modes of transportation, which makes the solar chargers a great solution to keeping your phones and tablets charged until you reach your intended destination.
  • When you return from hiking or camping in the woods, you’ll most likely need to clean your solar window chargers before putting them away. All you need is a little dish soap and water. Moisten a lint-free cloth with the soapy water and wipe down the front and back of the charger. Repeat with a clean cloth that has been moistened with water only to rinse away any soap. Dry with a lint-free towel afterward. It’s important that you never use a scouring pad, wool scrubber or an abrasive cleaner on the solar window chargers. These will scratch the surface of the chargers and render them less effective.
  • The price for a solar window charger varies based on construction material and special features. The FEELLE 24000mAh Waterproof Solar Charger, 3-Panel is among the most affordable, while the GoerTek 25000mAh Portable Solar Window Charger and the Hiluckey 25000mAh Outdoor Solar Window Charger, 4-Panel are both moderately priced. You’ll pay the most for the Anker 21W Portable Solar Window Charger, 4-Panel, which is quick to charge.