Temu 10W Folding Solar Panel
Introduction
In this post, we have another somewhat affordable and pocketable 10W folding solar panel that we'll be putting through its paces.
The panel is available from all the usual places and I have links to most of them below.
Amazon US - I couldn’t find it on Amazon US
When I bought the one I'm reviewing it was £26.48 from Temu (not including a big discount coupon that they regularly provide).
First impressions
Size and Weight
This panel is a very manageable size, together with the smooth edges it would easily slip into almost any pocket and also not take up too much space. The panel would fit almost anywhere in a bag and would even fit anywhere a phone would due to its similar size to an average-sized phone.
The actual dimensions are:
Folded: 16 x 9 x 3cm
Opened: 55.5 x 16 x 0.7cm when measuring at the thickest part that contains the USB outputs the panels themselves are approximately 0.3cm
The effective PV area is 0.0078m^2 per panel, using solar irradiation of 1000W/m^2 and an efficiency of 20% that’s 1.56W per panel and there are five of them so approximately 7.8W of panel area in total.
Weight: 252g
Construction and Features
The panel is constructed of an ABS plastic shell on the USB connections section, the material on the back of the flexible solar panels claims to be “soft leather”, it feels a little plasticky with a regular embossed pattern, however, it has the smell of leather after a sniff. The front face around the PV cells is a softer feel material, is it leather too, I’m not sure, it looks a little too perfect, however, it does have the smell of leather too and maybe that’s where some of the cost of this panel lies as it’s not super cheap.
When folded the panel has an elasticated closure that is fastened by a pop stud. This elasticated closure can also be used to fasten a battery back or phone to the USB section of the panel while charging which is quite useful. You can see a larger battery back that has six user-replaceable 18650 Li-Ion cells in the image below being held in place by the strap.
Once opened this reveals the four solar panels that this panel consists of, they're not that big at about 16x8cm each which does start to make me doubt the 30W claimed output and does line up with the more likely 6.5W output. The panels are covered by what does feel like a tough and durable polymer covering that has a matte finish.
In the opened state you have two steel eyelets to attach the panel to a pack, tent, or any other object. The seller does include two small carabiners to aid in connecting the panel to the item of your choice, it's worth pointing out that the quality of the carabiners isn't the best and one did immediately lose its ability to spring closed the first time it opened.
Outputs
This panel has two output options, a short pull-out USB micro cable and a USB A port both on the same side of the hard shell. As it;s 2023 and even Apple has succumbed to the pressure and moved over to USB C, I’d like to have seen one or both as USB C, maybe something we can expect in a newer version.
Testing and Performance
Test Setup and Conditions
To test, I followed the standard testing procedure of taking the panel up onto our roof terrace and plugging it into my homemade load and data logger.
It's early September here and the weather while warm was quite hazy and cloudy, the temperature on the test day was 30C.
The panel was left in the sun logging the voltage, current, and light intensity over 30 minutes, this was recorded onto a SD card that was then exported to Excel for analysis.
Testing Results
Data time! here is the recorded data from my testing over 30 minutes. I had some issues as this was the first time I used my light sensor, the direct sunlight maxed out the BH1750 light sensor giving a reading of 54612.5 at some points. I’ll be redoing the testing for this panel, however, the times when the sensor wasn’t maxed out are still useful.
Measurements
Max Power: 2.12 W
Average Power: 0.82 W
Max Solar Irradiance: 455.09 W/m^2
Average Irradiance: 320 W/m^2
*Note: the solar irradiance is derived from the ratio, Solar Irradiance of 1 Sun (1,000 W/m2) equals approximately 120,000 Lux as outlined in this paper.
Derived Measurements
Ave. Efficiency = 12.15%
Max efficiency = 13.68%
These efficiency numbers aren’t super useful as the light conditions were never going to reach their optimal performance numbers in less-than-perfect sun.
During the 30-minute test it managed to put 0.736Wh into the battery pack, that’s not bad and in the test conditions would charge a 10Wh 18650 in just under 7 hours or a 13Wh iPhone in almost 9 hours. If you were blessed with clear skies and bright sun then these times could be up to 50% less.
Charts
Power vs Solar Irradiance
As you can see, as per the panel I tested last week, the irradiance is clipping as the sensor has gone out of range, this panel was tested on the same day and so was affected by the same issue. I now have an ND filter for the sensor and will be applying it to the next test I perform.
Power vs. Efficiency
From the data above, the day wasn’t very sunny and had cloud and haze. The approximate irradiance of 350 W/m^s seems about right and the output power of panel isn’t too far off what you’d expect from the theoretical panel power based on the size and the weather conditions.
Scores
Now to the scores out of 10
Build quality = 7
Given the materials and the clean build I’d say this was a solid panel, it should last a while, the only question mark would be the micro USB pigtail as it feels quite flimsy.
Claimed output = 8
Though the weather conditions weren’t perfect, the power it generated was about right for the claimed power and the conditions.
Packability = 7
Being approximately the same size as a modern phone albeit a bit thicker it will fit in many places, the only negative is that at 250g though not heavy it’s still a reasonable weight.
Efficiency = 6
It seemed to perform quite well in the conditions and considering the total PV area.
Value for money = 4
I think it’s just a little too expensive for the output even if it made the full 10W, I’d feel more comfortable paying around £15 for it.
Average Score = 6.4
Conclusion
I think in summary this panel isn’t a bad little panel, it’s not a powerhouse but it could realistically collect enough power to charge your phone if you have perfect sun and can dedicate the time to charging a power bank all day. with the lack of mounting points this does really limit this panel to being placed on a flat surface.
I’m not sure there are too many use cases where you’d need to be stationary and the only option was to place it on a flat surface where another type of panel wouldn’t be better suited. The best use for this panel would be where you have limited pocket space and where you have a small pocket and don’t really need to charge any devices and just need something for an emergency.
Bottom line, while not a bad panel, I think there are definitely better panels out there and I should have some reviews of them in the coming weeks and months! :)
Links if you want to buy this panel
Amazon US - I couldn’t find it on Amazon US
