Efficient and stylish, the PowerGreen's main attraction is its user-friendly design. It comes in multiple different color options and has easy to follow instructions written on the panel itself. This makes it approachable and very easy to use. The panel also has a large storage pocket and no extra material, unlike the X-Dragon, which contributes to its smart design. Overall, the panel performed well and comparably to the other panels in its class, but its heavy weight and difficulties charging multiple devices at once made the PowerGreen fall short in our side by side comparisons.
PowerGreen 21W Review
Cons: Heavy, bulky
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Our Analysis and Test Results
The biggest draw of the PowerGreen 21W panel is its design. From the materials used for its construction, mainly the PET Polymer faced panels (which are incredibly durable) to the thoughtful, roomy storage pocket, the 21W is easy to use. On the downside, it is less powerful than the BigBlue 28W and it lagged behind in our tests even in perfect solar charging conditions. In addition, the PowerGreen is the heaviest set-up in our testing fleet.
Charge Interruption Recovery
In our charge interruption tests, the 21W by PowerGreen did not quite stand up to the BigBlue 28W and the X-Dragon 20W panels. Initially, the PowerGreen charged up our battery to 3%, just as the other larger capacity panels did. But, once we had interrupted the steady flow of sunlight to the solar cells, the panel had trouble re-connecting to the battery that was plugged into it. The battery wasn't charging at all after the panel had been shaded, and we had to unplug and re-plug it back in to reestablish a sound connection. Some panels have technologies built in that will read the input and readjust accordingly, like the iSolar system in the X-Dragon panels, and that makes their recovery faster.
Charging speed was another category where the PowerGreen narrowly missed the performance level of the other two large capacity panels. After one hour of charging our 1byone 6,000 mAh external battery pack, the PowerGreen had only charged the battery to 13%, compared to the X-Dragon which was at 21%. This is a fairly large difference, especially when we checked again after three hours and the PowerGreen was still almost 10% behind the other two panels. This lag played a large role in the PowerGreen's lower overall score, since keeping a phone or battery charged is the main job of these devices.
Multiple Device Charging Speed
When we plugged in two of our test batteries to the 21W, we found that the panel slowed down considerably in delivering power to both batteries. This is normal, since suddenly each USB port is pulling half the total wattage of the panel, making it seem like they are each plugged into a 7-10W panel. This slows down the charging a lot, but some panels recover better than others. This contender was able to maintain a charge to both batteries, but failed to actually increase the charge on either. Some panels, like the X-Dragon, could not consistently supply power to the batteries. This caused the battery to continually disconnect and reconnect, rather than receive a steady flow of power.
The 21W panel's greatest attributes are its design. The panel is burly and can withstand wind, light rain, and sand (to an extent!). If you like hanging your panels up to receive sunlight, the PowerGreen has re-enforced grommets that you can trust to hold up the panel for a long time. The durable canvas and PET Polymer coating on the cells makes the PowerGreen especially durable. We didn't run into any issues with the pocket wearing or the fabric wearing out along the fold lines, though a few contenders, like the BigBlue 28W and Instapark Mercury 10 offered a higher level of durability.
Weight & Portability
The larger the wattage, the heavier the panel, generally speaking. With this in mind, it's not surprising that 21W is the heaviest of the nine panels in our tests. The PowerGreen weighs three ounces less than the BigBlue 28W, though it has a smaller capacity. Folded up, the PowerGreen, BigBlue, and the X-Dragon are all relatively the same size, but on a backpacking trip or when traveling internationally, the ounces really do add up.
This user-friendly is a good option for car camping or "van life" where you are mobile and off the grid, but not carrying all your worldly possessions on your back. Since you can pick out your color choice and hang the panel in your window using the reinforced grommets, this panel does better in the back of your car, rather than taken with you on your human-powered adventures. There are lighter and equally powerful options, such as the Renogy 10W, that work better for light and fast outings.
This panel rings in at $50, almost half the price it originally sold for. For $50, it has a careful design and high powered solar cells, and is comparable in price to our Editors' Choice Award Winner, the BigBlue 28W, though that panel is lighter weight and more powerful for only around $15 more.
The PowerGreen 21W has lots of bells and whistles that make an aesthetically appealing purchase, but after some further research, it seems like it may not be all its cracked up to be. The PowerGreen is efficient, since it is a 21W panel, but still struggled to charge two batteries effectively. It also lagged in the race to charge our battery pack, getting beat by the BigBlue 28W and the X-Dragon 20W panel. For these reasons, we found that there are better options if you're looking for a panel of this capacity.
— Jane Jackson