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FlexSolar 40W Review

This panel quickly unfolds to six panels for fast and efficient charging and packs away just as easily
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FlexSolar 40W Review (The FlexSolar 40W is portable enough to carry with you wherever you go and powerful enough so you won't be left...)
The FlexSolar 40W is portable enough to carry with you wherever you go and powerful enough so you won't be left waiting for a charge.
Credit: Sam Schild
Price:  $105 List
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Manufacturer:   FlexSolar
By Sam Schild ⋅ Review Editor  ⋅  Oct 19, 2023
63
OVERALL
SCORE


RANKED
#4 of 12
  • Direct Solar Charging Speed - 35% 7.0
  • Indirect Solar Charging Speed - 35% 4.5
  • Portability - 15% 6.0
  • Functionality - 15% 9.0

Our Verdict

The FlexSolar 40W is one of the highest-watt panels we tested that you can still reasonably carry in a backpack. This panel unfolds from the size of a book to a massive chain of six durable, high-quality solar panels. It's one of the most powerful panels we tested and one of the few panels with DC charging capabilities. When we tested this panel's DC output, it blew the competition out of the water. You can use this model to directly charge your devices, or hook it up to a large portable power station to keep laptops and other off-grid living items running. It's not the most portable, but this is downright tiny compared to other 40+ watt panels. If you're looking for a portable panel that is still small and packable enough to carry in a backpack, this is the one we recommend.
REASONS TO BUY
Folds and unfolds quickly
Portable size
Fast DC charging
Multiple USB charging ports
REASONS TO AVOID
Relatively heavy
Nothing to protect the charge controller and outputs

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FlexSolar 40W
Awards Top Pick Award Editors' Choice Award Best Buy Award  Top Pick Award 
Price $105 List
$89.99 at Amazon
$70 List
$58.37 at Amazon
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$80 List
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Bottom Line With easy to setup and even faster folding, this panel will have your devices charging at 40 watts in no timeFor an easy-to-use and efficient solar charger, this panel will keep your tech chargedThis panel works well as a portable solar charger and costs less than the competitionThis portable solar charger has average charging speeds and is very durableThis panel is small and light enough that you'll always want to carry it with you
Rating Categories FlexSolar 40W BigBlue SolarPowa 28 X-Dragon 20W SunJack 25W Goal Zero Nomad 5
Direct Solar Charging Speed (35%)
7.0
9.0
7.5
6.5
4.5
Indirect Solar Charging Speed (35%)
4.5
8.0
6.5
4.0
4.0
Portability (15%)
6.0
7.0
7.0
7.0
9.0
Functionality (15%)
9.0
9.0
7.0
7.0
6.0
Specs FlexSolar 40W BigBlue SolarPowa 28 X-Dragon 20W SunJack 25W Goal Zero Nomad 5
Power Output (Watts) 40 W 28 W 20W 25 W 5 W
Energy Generated in 1 Hour Direct Sun 902 mAh 1849 mAh 1043 mAh 624 mAh 318 mAh
Energy Generated in 1 Hour Indirect Sun 195 mAh 919 mAh 535 mAh 105 mAh 65 mAh
# of USB A Outlets 1 3 2 1 1
# of USB C Outlets 1 0 0 1 0
Max USB Output Current (Amps per Port) 2 amp 2.4 amp 3 amp 2 amp 1 amp
Weight (Measured) 47.25 oz 20.9 oz 21.7 oz 29.4 oz 12.35 oz
Size Folded 11 x 7.5 x 1 in 11 x 6 x 1.5 in 12.1 x 7.2 x 0.51 in 12.6 x 7.8 x 0.8 in N/A
Size Opened 49 x 11 x 0.1 in 31 x 11.5 x 0.2 in 23.3 x 12.1 x 0.12 in 24.6 x 7.8 x 0.8 in 9.5 x 7 x 0.8 in
Battery Included No No No No No
Battery Capacity (mAh) N/A N/A N/A N/A N/A
Tablet Charging Yes Yes Yes Yes No
Laptop Charging Yes Yes No No No
Charge iPhone/Smartphone Yes Yes Yes Yes Yes
Panel Exterior Material Plastic Polyester Oxford fabric PTFE PET polymer fabric Hard plastic
Panel Type Monocrystalline Monocrystalline Monocrystalline Monocrystalline Monocrystalline
Battery Input (Volts / Amps) N/A N/A N/A N/A N/A
USB Output Yes Yes Yes Yes Yes
Able to Daisy Chain No No No No No
12-Volt Connection Yes No No No No
DC Output Yes No No No No

Our Analysis and Test Results

The FlexSolar 40W is a highly durable, powerful, and portable mono-crystalline solar charger. It is one of the few portable panels we tested that has a DC output in addition to its two 2-amp USB-A ports and a single 2-amp USB-C port. It unfolds quickly and easily into a 49-inch long, 11-inch tall, and 0.1-inch thick, six-panel array. Folded away, this 47.25-ounce solar charger becomes just 7.5 inches long and 1 inch thick. The rugged design is thin enough to be highly portable yet strong enough to handle the abuses of daily use.

Performance Comparison


flexsolar 40w - the flexsolar 40w is portable enough to carry with you wherever you...
The FlexSolar 40W is portable enough to carry with you wherever you go and powerful enough so you won't be left waiting for a charge.
Credit: Sam Schild


Direct Solar Charging Speed


The FlexSolar 40W performed relatively well in our direct solar charging speed test. It has a DC output, which is unique among smaller solar panels. When using this output, the solar panel performed exceptionally well. When testing the USB output charging capabilities, it also performed well, albeit not entirely as well as the DC output.


To test direct solar charging speed, we hooked up every panel to an identical 10,000 mAh battery bank and left them in direct sunlight for one hour. Afterward, we discharged each batter using a digital USB multimeter and recorded the mAh of charge each panel generated. This test was repeated three times, and we averaged the results.


On a sunny day at 5,000 feet in Colorado, the FlexSolar 40W generated 713 mAh of charge on its 10,000 mAh test battery. That's more than most other panels we tested. When we tested the DC charging capabilities of this model, also on a sunny day in Colorado at a similar elevation, the FlexSolar generated 1466 mAh of charge on a 167-watt-hour power station.

Overall, the FlexSolar 40W performed better than smaller, lower-watt panels but not as well as the highest-performing panels in direct solar charging. Its DC output charging capabilities, however, are better than any other panel with a DC output, including some 50-watt panels we've tested.

flexsolar 40w - the flexsolar blew the competition out the water in a dc output...
The FlexSolar blew the competition out the water in a DC output charging showdown, but performed about average when charging USB devices.
Credit: Sam Schild

The FlexSolar 40W was about average when testing its USB device charging capabilities. If we only tested the USB charging capabilities, this panel would not have scored as highly in this metric. On the contrary, if we were only testing on DC charging capabilities, it would have scored even higher in the direct solar charging metric.

It has a total of six panels — that's a ton of surface area. It's rated at 40 watts of electricity, higher than most portable panels we tested. In our testing, it never actually put out 40 watts at once, but it still created more measurable watts than any other panel we tested. In our experience, most solar panels are rated for a wattage output that is only attainable in ideal conditions, so no panel ever puts out the watts it's rated for. The FlexSolar puts out more watts than most of the other panels we tested, whether or not it puts out the 40 watts it advertises.

flexsolar 40w - the flexsolar 40w has the most panels of any portable solar charger...
The FlexSolar 40W has the most panels of any portable solar charger we tested, which contributes to its high power output.
Credit: Sam Schild

Indirect Solar Charging Speed


The FlexSolar 40W performed about average in our indirect solar charging speed test. In our simulated cloudy day test, it didn't perform as strongly as it did during direct charging tests, but here again, it performed better when we used the DC charging output.


For our indirect solar charging speed test, we repeated the direct solar charging test using a white sheet suspended over the panels to simulate a cloudy day.


On another Colorado day at 5,000 feet, the FlexSolar 40W, with a white sheet suspended over it, generated 195 mAh of charge on its 10,000 mAh test battery. This isn't nearly as well as it performed during direct solar charging, but it still generated more mAh than most other small panels it was up against.

flexsolar 40w - the flexsolar 40w performed about average in indirect solar charging...
The FlexSolar 40W performed about average in indirect solar charging tests.
Credit: sam schild

Portability


For a 40-watt panel, the FlexSolar 40W is highly portable. It folds away into a small enough size to carry in a backpack. Though it isn't the lightest panel we tested, it's light enough to load up and carry with you.


The FlexSolar 40W features a simple folding design so you can quickly unfold it and get set up. It has no velcro or other clasps to mess with while unpacking. It simply folds and unfolds into a relatively small package.

flexsolar 40w - the flexsolar 40w is surprisingly portable for a 40-watt panel.
The FlexSolar 40W is surprisingly portable for a 40-watt panel.
Credit: Sam Schild

The FlexSolar 40W is far from the lightest panel, but it's not the heaviest either. At 47.25 ounces, this panel weighs less than the higher-watt panels we tested but much more than the smaller, lower-watt panels. These findings aren't surprising, but it's worth noting for those prioritizing weight.


Though it doesn't have a way to secure it when folded, it never seemed to be a problem for our testers. We packed and unpacked this panel repeatedly and never found it to be an issue that it didn't latch closed. In fact, we found that this design actually made it easier to unpack when we needed to set it up.

The FlexSolar 40W features six panels that fold up quickly and easily.
Credit: Sam Schild

The solar charge controller has nothing to protect it, though. This means it has exposed USB and DC outputs. We didn't have any issues with this, but we could see this lack of protection being a long-term problem. There is nothing to prevent these connection points from accumulating the inevitable dirt and debris that comes with anything used in the outdoors.

flexsolar 40w - the charging ports have no cover or any sort of protection from the...
The charging ports have no cover or any sort of protection from the elements.
Credit: Sam Schild

Functionality


The FlexSolar 40W is one of the most functional portable solar chargers we tested. It features three different outputs: USB-A, USB-C, and DC. It also has carabiners and enough loops to make it possible to hang this panel just about anywhere.


No matter what kind of device you need to charge, this panel is capable. You can charge anything from large power stations and laptops to smaller USB devices with three different outputs.

Like most portable solar panels, the FlexSolar 40W has carabiner loops and comes with carabiners to hang it to charge. It doesn't have legs to angle it at the sun, but between its small size and included carabiners, it's easy to find a way to point it at the sinking sun.

flexsolar 40w - the flexsolar has carabiners and loops to hang it so you can set...
The FlexSolar has carabiners and loops to hang it so you can set this up just about anywhere.
Credit: Sam Schild

Should You Buy the FlexSolar 40W?


The FlexSolar 40W is an excellent option for a high-watt output solar panel that is still relatively portable. It packs away quickly and easily and unpacks just as readily. Many panels are more portable than this one, but none are as portable and have this high of a watt output. If you're looking for a large-capacity solar panel to charge a lot of devices while remaining relatively portable, this is a great option.

flexsolar 40w - the flexsolar is small enough to bring anywhere and powerful enough...
The FlexSolar is small enough to bring anywhere and powerful enough to power all your devices.
Credit: Sam Schild

What Other Portable Solar Chargers Should You Consider?


If you're looking for a more portable and affordable option, check out the BigBlue SolarPowa 28 or the even less expensive, lower capacity X-Dragon 20W. If you're looking for a larger, higher-watt option, check out the Goal Zero Nomad 50 or an even larger 100+ watt solar panel.

Sam Schild