A workable solar panel at last?

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Re: A workable solar panel at last?

Postby Mark F » Sun 04 Oct, 2020 12:41 pm

This old thread discusses the system I use https://bushwalk.com/forum/viewtopic.php?f=21&p=305448. I use a repackaged Miller 102 charger (16g), Panasonic NCR18650B 3400mAh batteries, either 1 or 2, and a short USB cable (8g). A 1 cell system weighs 70g and for each extra cell add 46g plus the weight of a small case for the loose batteries. My 2 cell Anker powerbank is 148g so if I carry two cells I save about 35g.

As I understand if using single cells in a decent device, unprotected cells are fine (mine are unprotected). The Miller charger has a 5 led charge meter along one side - not obvious in photos and I just check it every now and then to see if it has finished charging. If so I swap on the phone etc to top them up.
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Re: A workable solar panel at last?

Postby keithy » Sun 04 Oct, 2020 12:49 pm

Xanthorrhoea wrote:.. I've been charging a few devices to see what it can do. I am keen to get an update on your own experiences with this panel, especially now its been a couple of years, hear about any trips, your successes or challenges with the solar panel and charging devices? I am walking the AAWT next year, never owned a hiking panel, and want some reassurance that my $10.40 solar panel (including postage!) is up to it. Thanks in advance - Marc

With my 6.5W panel when it was new, I would get around 4000-5000mAh topped up in a powerbank in around 5-6 hours in real world, optimal sunlight use. That sat well with my controlled testing. I would get between 0.6A to 1A. Your results may vary depending on the panel, the sun angle, your cables and your powerbank/phone.

When walking, especially in the mountains above trees, I would put the panel on my pack orientated to the sun, so if I was walking away from sun, it would be on the back of my pack, and I would move the panel to the either side of the pack to face the sun depending on the direction of travel for the day. If I got to a campsite early enough, I would set the panel up facing the sun.

PICT_20191025_135139-01 (Small).jpeg
Borjomi National Park Georgia
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Torres Del Paine Chile
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I did notice that in my recent trip to Patagonia in January, the performance of my panel seemed lower than when it was new. I am going to run some tests on the outputs to see if it is due to the panel, or the USB socket (which is a little loose now), or my cables.

For your question on charging, I usually use a powerbank, but like Mark, I also have various single cell AA/Lithium USB input chargers, and I have on occasion directly charged a 14500 or NiMH cell with the solar panel.
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Re: A workable solar panel at last?

Postby ChrisJHC » Sun 04 Oct, 2020 1:02 pm

I find I get best results by using the solar panel to charge a power bank and then charge my devices from the power bank.

Particularly with more “sophisticated” devices such as iPhones.
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Re: A workable solar panel at last?

Postby keithy » Sun 04 Oct, 2020 1:16 pm

Xanthorrhoea wrote:... change in model (colour) by Fastech, I'd held out until last week, and just as I gave up it finally arrived. I've been charging a few devices to see what it can do....


I'm curious, which panel did you get?

The one that I mentioned, and Mark F and others refer to in this thread is this one with the red arrow in my collection of various panels from a pic taken last year.
Solar Panels.jpg
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The reason I ask is that Fasttech stopped stocking that 6.5W panel sometime last year. I checked around November 2019 and the SKU was taken off their site, replaced with a different model.

There is one that is $10.41 (SKU 9708339 - https://www.fasttech.com/p/9708339), that looks similar to a panel that I also have (in the picture, to the left of the panel with the red arrow is the panel with the built-in "handle"). But the solar panels used and the controller box appears to be different to the one I have. So there's a good chance the performance of mine would not match the one that you've got.
SKU 9708339Screenshot.jpg
Is that the one you ordered?


There are a quite a few 6.5W panels floating around Fasttech and Aliexpress, that have come from the failed share Limebikes. These panels are reputedly quite hardy (designed to sit at the bottom of the handlebar basket of the Lime sharebikes), but were designed to output 12V. Some resellers have installed their own 5V output controllers and these panels are being currently sold like http://www.aliexpress.com/item/33024560385.html I haven't tested these yet though.

I did pick up a similar panel from Fasttech, and only received it about 2 weeks ago (SKU9726595 - https://www.fasttech.com/p/9726595)
SKU9726595  Screenshot.png

It looks ok, but I was disappointed that mine came with very poor gluing to the USB output controller. There was barely a dab of glue holding the controller to the board, and the soldered leads were the only thing holding the USB controller in place.
SKU9726595  badly glued.jpg
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I use various USB meters to check the output of my solar panels - these are basically in-line USB ammeters.
USB Meters.jpg
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For example, these are some of my meters. The very basic ones like these "USB Charger Doctor" only display the Voltage and Amperes when the solar panel has sunlight. I would manually record the maximum Amps and the charging duration, but this wouldn't be the most accurate as it would stop when the sun was under cloud cover, and I didn't monitor the charge every second.

The other meters I have in my toolkit have the ability to display the cumulative mAh passed through. However, not all these are great with solar panels. These USB meters do not have built in power supplies to run the screen, and "borrow" power from the source - in this case the solar panel. While the amount of current it uses isn't much at all, but in some cases, I think that using with solar panels might have some issues.

For example, the black one (Keweisi MX18) with the lovely colour oLED display screen displays the cumulative mAh (and Wh) and the time taken to charge as well as the Voltage and Amps, and the temperature. However, to my dismay I found out the memory is destructive when used with a solar panel, and would reset once the solar panel is obscured and input power is cut. This isn't meant to happen as it has 10 memory slots and using USB power (either a powerbank or wall socket), if the power is cut, it stops and when power reconnected, it continues the recording from the time the power is cut. I haven't quite worked out why it resets the memory count on Solar Panel, potentially due to the voltage dropping to a certain level, but that makes it not useful to test my panels in the field.

The silver/blue Keweisi KWS-V20 meter shows the cumulative charge in mAh, and does work as intended to record the solar panel output, even when the solar input is interrupted. It is about 4-5 years old though, and has a few issues now.

I have a few other fancier and more expensive meters, like the rather pricey yzxStudio zy1280 meter, and the cheaper Ruideng UM34C. I did something stupid with my zy1280 meter and it no longer functions.

The UM34C (yellow meter in the picture) is great and displays a great deal of information, but the memory also destructive when the power is cut. I got this tester as it has both a USB C and micro USB input, and I thought I could externally power the USB meter with a smaller battery bank when plugged into the solar panel, so that when the sun was obscured, the tester meter wouldn't reset. But alas the USB C and micro USB inputs are to test the resistance to USB C / micro USB cables, and not to power the unit.

The UM34C has a great Bluetooth function where I can log the results in a spreadsheet on a phone or a PC, but again, when the sun cuts out, the meter resets and the bluetooth connection is severed. If I don't manually reconnect, it doesn't record the data to my phone, even when the sun is no longer obscured.

So, long and short of it, while I can do tests on the panels in a controlled environment like the back yard on a sunny day, and I will take this as the maximum output the panel can achieve. In practice in field use, strapping it to the pack in non-optimal angles to the sun, and walking under tree cover, in shade of mountains or clouds, it can be 50%-80% of the amount taken under my controlled test.

On bad days like walking entirely under tree cover, or in valleys, of course you will get zero power from the panel.
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Re: A workable solar panel at last?

Postby Xanthorrhoea » Sun 04 Oct, 2020 5:09 pm

Hi Keithy, in answer to "I'm curious, which panel did you get?". I think you are right, I got the SKU 9708339 model; I'd originally ordered the all-black SKU 9708340 variation. To me it looks identical to the panel in your picture (with the red arrow). Sad to hear that it may not live up to the older model as the controller box I have is an exact match to what appears in the add link you posted. Thanks for the information on your testing and the other options and good to hear of a ballpark figure of what to expect when its on a pack. - Marc
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Re: A workable solar panel at last?

Postby Xanthorrhoea » Sun 04 Oct, 2020 5:26 pm

Thanks Mark and all contributors. That is great information. I will emulate the charger pack, that will work well for me, and the low weight is brilliant news.
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Re: A workable solar panel at last?

Postby ribuck » Sun 04 Oct, 2020 5:37 pm

Xanthorrhoea wrote:are you using a standard power bank, or is it something with protections (like for overcharging, or do you find you can keep a close eye on it)?

With these small panels, a cheap "lipstick-shape" power bank is just fine. These are all protected against being charged too much. They may not be protected against being charged too quickly, but these solar panels can't do that anyway.

However, these small power banks typically use four LEDs to show the state of charge, therefore you can't easily see how well it's doing. I also have a slightly heavier power bank that has a percentage display, which is very reassuring because you can easily see that the charge is increasing.

I get at least 2500mAh per day if I'm walking out in the open; much less if under trees some of the time, and very little in rainy weather.
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Re: A workable solar panel at last?

Postby johnrs » Thu 17 Dec, 2020 4:42 pm

Hi Folks
Has anyone come across a light but foldable panel similar to the Fastech 6w 5v model shown above?
Thanks
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Re: A workable solar panel at last?

Postby Mark F » Fri 18 Dec, 2020 12:06 pm

I have not seen a folding version but adding a fold will increase weight and seems unnecessary. My cut down version is 130mm x 270mm (88g) add 15-20mm to each dimension for the size as delivered. At that size they easily slip into the rear pocket of my pack and will also fit in the side pockets. I tend not to walk with the panel active unless I am in very open country.
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Re: A workable solar panel at last?

Postby lseries92 » Fri 18 Dec, 2020 2:02 pm

I have a folding one but I can not recall where I bought it from although someone may be able to id it from the picture below. It is 200 grams as was able to handle two phones, two headlamps and my Garmin Inreach for the 20 days to do the Larapinta. I do have a white single one like the others and while I recall this had a higher output, it was certainly not twice as much considering the increase in weight.

I used it for a few multi-day hikes including Larapinta a few years ago and it worked well until it stopped working on the last night of the Larapinta right before we were going to climb Mt Sonder in the morning darkness (fortunately we still had tons of battery left).

I found that it would work if I put pressure on the plastic magnetic clasp (on the right hand side) which is where the USB Type A connection is integrated into - I used a small bulldog clip to make it work unattended. Recently it has stopped working completely - I have not opened it up to see why it failed but the addition of a fold obviously does introduce an extra point of failure, especially in these cheap panels that are trying to save space/weight.

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Re: A workable solar panel at last?

Postby Lord Backcountry » Mon 01 Mar, 2021 12:10 pm

Hi all -

I'm starting to plan a 1-2 trip week in Kozzie for winter 2022. I'm still scouting locations with the big picture plan to set-up a base camp and do daily explores from there.

Most items are sorted but I'm thinking hard about power options.

I currently use a couple of Anker power banks recharged from an Anker foldable solar panel (as featured above). This has worked well to date but less so in four day blizzards.

So I'm thinking supplementary options, including wind power. There are a couple of kits available on ebay but they look pretty cheap and nasty. I don't think power output has to be great as I'm thinking only trickle re-charging to supplement the solar panel. If anyone has any direct experience with this, I'd be grateful to hear.

[I also note a much less practical option for this trip is water/creek recharging, but I'll throw that into the mix a well.]

cheers

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