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Latest, Lightest Solar Charges?
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Richard Malpass

Locale: Australia, Planet Earth,
Latest, Lightest Solar Charges? on 02/24/2012 15:53:03 MST Print View

Im looking for a light weight solar charger for kindle and camera and probably GPS at some stage in the future. Ive looked through old threads, but theres not many new threads as of late and the way technology changes I thought its time for a new thread :)
So, whats the latest and lightest solar charger?

John Jensen
(JohnJ) - F

Locale: Orange County, CA
Re: Latest, Lightest Solar Charges? on 02/24/2012 16:04:07 MST Print View

I haven't tried this, but these "how to" instructions describe a self-built solar power charger for usb-powered gadgets.

Richard Malpass

Locale: Australia, Planet Earth,
Re: Re: Latest, Lightest Solar Charges? on 02/24/2012 16:48:28 MST Print View

I prefer to purchase a complete unit if possible...I remember playing around with electronic circuitry as a kid and building a few things, however not as of late.
I would probably blow something up today!

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Latest, Lightest Solar Charges? on 02/24/2012 16:56:39 MST Print View

Richard, before you go shopping too far for a solar charger, you want to get a good grasp on how much charger output you need.

If you say, "I need +5 volts, 1 amp, for one hour per day" that means something.

If you say, "I want to charge my Kindle and my camera" then that means nothing at all.


Richard Malpass

Locale: Australia, Planet Earth,
Sorry for not being tech savie... on 02/24/2012 17:01:29 MST Print View

Sorry for not being tech savie...but how do I work out that?

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Sorry for not being tech savie... on 02/24/2012 17:09:53 MST Print View

Look up the specs for your devices. How much capacity in miliamps. How much do you use per day (not perfect way to do it) percentage-wise. Do they last 1, 2, 3 days, etc.? Now you can figure out how much you need to but back in. Ohm's Law is the basic formula for calculating electrical stuff... a little research and study on the Web or other places will be beneficial.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Sorry for not being tech savie... on 02/24/2012 17:17:36 MST Print View

Additionally, you need to take the solar charger specifications with a grain of salt. Often they quote some good numbers, but you won't get that kind of maximum performance unless you are sitting in Nick's backyard in perfect sunny weather. I've engineered some larger systems, and I always throw in a +50% factor to account for less-than-maximum solar output.


Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Re: Sorry for not being tech savie... on 02/24/2012 17:32:11 MST Print View

Excellent point by Bob. You need to look at your latitude, time of year and weather. All big factors.

For example my tent trailer's solar system can recharge my batteries in a couple hours after a lot of night use... under ideal conditions. But I have a large battery bank (250 amp hours) and a 250 watt solar array. That way if it rains for a week I do not have to be concerned about power (no sun), I have plenty of battery reserve and when the sun comes out can recharge it fairly quickly.

Now if you have a nominal system, when backpacking, that can only replenish what you use under optimum conditions and no method for reserve capacity, you are going to end up with some dead batteries.

I have a GoalZero panel and battery pack but have not really played with it much (it was a gift). If I were to bring electric devices backpacking I would probably be better off with spare batteries and on a long trip like the PCT would recharge at stops in town. Unfortunately the most popular phone, the iPhone, has an internal non-field replaceable battery... a big negative for that device.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Sorry for not being tech savie... on 02/24/2012 17:48:54 MST Print View

Yes, Nick. You can get into all sorts of things like sun angle.

If a backpacker intends to do solar charging on the trail, then he needs to factor in whether he is north-bound or south-bound, because the sun tends to be in our southern sky.

I agree that most often, the best solar charging solution for a backpacker is none at all. Replacement batteries are often lighter in weight. Or, if you can't replace them, a "battery brick" can be used to charge up smaller devices.

I was on a 25-day trek one time, and I kept my cameras going with a whole pocketful of lithium primary batteries.


Colin Krusor
(ckrusor) - M

Locale: Northwest US
Solar charger on 02/24/2012 18:09:32 MST Print View

You said that you want an off-the-shelf charger, I realize, but it might be prudent to see if you can have someone make one for you. Small photovoltaic cells are now available with better than 20% efficiency, but you will never find any stock USB solar charger incorporating PVs with efficiency greater than about 8-12%. Some remote-control airplane enthusiasts with electrical engineering expertise have posted on online RC forums about extremely lightweight and efficient solar chargers for RC airplanes. These would be far lighter per unit power output than any stock solar charger that I know of.

David K
(aviddk) - F

Locale: SW Oregon
Wired 01/2012 review on 02/25/2012 09:02:30 MST Print View

Wired reviews four portable solar chargers in an article dated January 31, 2012 here.

Brenton Rodgers
(GreyBeard) - M

Locale: Canberra
Latest, Lightest Solar Charges? on 12/17/2012 20:35:07 MST Print View

On the face of it, the Freeloader Pico looks good. And only 49 grams.

Has anyone had experience with these?

Edited by GreyBeard on 12/17/2012 20:44:03 MST.

Kevin Burton
(burtonator) - F

Locale: norcal
Re: Latest, Lightest Solar Charges? on 12/17/2012 23:07:56 MST Print View

That Pico thing looks cool but 50g? No way that's the weight *including* the battery.

I suspect they're playing games. Seems too good to be true.

Though they DO say 14 hours to charge an ipod... which wouldn't really work in winter.

Matthew Hoskin

Locale: Kanangra-Boyd NP
Latest, Lightest Solar Charges? on 12/18/2012 00:02:23 MST Print View

Hey Richard,
I spend alot of time out in the bush, and take my Galaxy Tab 7 and phone and as I normally go solo I get bored at night and want to watch movies to pass the time. A few years ago I looked into solar and what I ended up getting was a rollable solar panel ( 28watts) and then a universal battery pack ( rated at 75 watt hours ). I can recharge the tablet about 4 times and if I just use the iphone for movies I can recharge around 6 times. Usually I can just take the battery and it will last a week. But..... What you should realize is that to fully recharge even AA batteries and a smartphone or a tablet, you need full sunshine and many hours.My recommendation would be to go on Alibaba and look at the foldable panels that are available from China. They will sell samples real cheap, I would look at something at least around 30 watts. Then the battery pack you can get from Alibaba as well. Look for a universal pack of at least 40 watt hours.
The big trade off is power vs weight. Unfortunately here in Australia there are very few options available and of the ones that are, they are all overpriced. Another good site to look at would be powerenz from the US and also Modern Outpost from Canada.
Hope this helps,

Edited by mattgugel on 12/18/2012 00:05:58 MST.

Ken T.
(kthompson) - MLife

Locale: All up in there
Re: Latest, Lightest Solar Charges? on 12/18/2012 06:42:00 MST Print View

Leave it to BPL members to come up with something.

Ryan Dorn
External on 12/18/2012 11:09:34 MST Print View

I've given up on solar chargers. They just seem finicky at best and I found myself fussing with them way too much to try to get them working right.

Instead, I carry 1-2 Anker 5600mAh external batteries which weigh 4 ounces each and are rather small. They cost around $30. Each one gives me about 3 complete iPhone 5 charges. On a 3 day trip, I'll take one. On a 7 day trip, I'll take 2. They've given me the reliable power that I need.

Edited by fiestabuckeye on 12/18/2012 11:13:36 MST.

Max Dilthey
(mdilthey) - M

Solar? Not yet. on 12/18/2012 11:46:06 MST Print View

We brought a solar charger with us while bike touring. Every time we went under a tree, the solar charge would kick out and kick back in. My phone turned off and on each time it sensed it was being charged, and used more power than we gained.

Never again.

Ryan Dorn
Max on 12/18/2012 12:06:33 MST Print View

That's the problem with solar chargers that feed directly to the device. I had the same problem. It was like I was plugging in and unplugging my device constantly and having the screen turn on.

Ideally, the best setup would be a solar charger like the Joos Orange which has a 5400 mAh internal battery. The solar panels charge the battery and you feed from the battery which creates a more consistent charge. That's a great solar charger, but at 24 ounces, it is not really an option for most of us that are weight conscious.

Edited by fiestabuckeye on 12/18/2012 12:15:31 MST.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Max on 12/18/2012 12:17:15 MST Print View

For those who have not been paying attention, the solution to this is called a charge controller. Some solar systems have the charge controller features built in. Many don't, because that means extra cost and extra weight, but not by much.

In 1997, I was visiting a solar installation owned by a Sherpa at 14,000' elevation in Nepal. Even he recognized the need for a charge controller, so he leaned on me to get him one. Upon my return to the States, I got him one and had it hand-carried to him.


Colton Akers
(Akers07) - F

Locale: Indiana
Powerfilm on 12/18/2012 20:48:50 MST Print View

I recently purchased the Powerfilm folding charger from I haven't used it, so I cant give you any feedback. But it does charge two AA batteries or you can charge direct. At 6.6oz thats much lighter than most out there.

Simon Roth

Locale: Northwest
JOOS Orange on 12/18/2012 22:01:13 MST Print View

I have the joos orange as well and love it's ability to charge and take a charge and all that. It's just a huge PITA to pay 150$ for something that ends up being one of the heavies things in your pack. Oh well, I've learned my lesson and will be getting an extra capacity battery case for my phone that will boost my battery life.

Now all I've gotta do is get rid of the JOOS.


Matthew Hoskin

Locale: Kanangra-Boyd NP
Re: Re: Max on 12/19/2012 00:34:01 MST Print View

You're absolutely right Bob!
A charge controller is an often overlooked piece of the puzzle that may do not realize is a SUPER important part of the equation.
I guess for those who are not in the know, the following is "really" the essentials to charge devices in the field.
1. Solar panel ( either foldable or rollable)
2. Charge controller ( to regulate the power from the panel as it fluctuates)
3. Powerbank ( storage for the power produced from the solar panel )

If you do your homework and take the time to learn about solar, you will realize that still now there are now real lightweight options. Sure you can get some little 5 watt panel with a 5V USB outut, but.... will take atleast 8-10hrs to charge a few AA batteries, in full sunshine. OK if you are staying put everyday, but for on the move, you really need a panel ( or set up ) that will charge a smartphone, or tablet or AA /AAA's. Let's say you are out for a weekend. Your best bet is just to take a batterypack/powerbank/etc,etc. Usually they are a Lithium Ion battery pack. For the above mentioned devices I wuld say a 40 Watt hour ( Whr) pack would suffice. Let's say you are wanting to watch a movie a night, well that would serve your needs. But.... if you go out for a week or more, then you will obviously need to think of charging that powerbank ( big battery pack ). The problem is that for us UL'ers, the only options are the rollable or foldable panels from either Powerfilm or Global Solar. - That is, they are the thin film technology products, but the trade off from light weight and packability is tht they are inefficient. I learnt the hard way, I lived in the High Arctic for 10 years, and at times spent weeks out camping/hunting etc, and needed to power/charge a GPS/ Iridium sat phone/ AA's etc, I bought a Iowa Thin Film ( powerfilm ) panel and unless I had fll sunshine ( yes only in summer or late spring north of 60!!!), it wouldn't even recharge the sat phone.
I then looked into the options, and learned about charge controllers, watt hrs, amp hrs, etc etc. In my opinion I would recommend you go for slight overkill and get a system that is more powerful than what your calculations work out to. Just think of how many days of your trip that you have full sunshine and are in a campsite etc that affords full sunshine???!!!. If you want to say keep an ipad/tablet, and a smartphone, and lets say 2x AA's alive for a week - then go for the highest wattage monocrystalline panel you can afford ( they come as foldable panels). At least a 40 watt panel is the realistic size. then get a 2 amp charge controller, and look for a lithium battery pack ( there re a million on Ebay and alibaba) at around 50+ watt/hrs). For trip and usage of around let's say 4-5 days - you can most likely get away with just the battery pack.Powerenz ( US cottage company ) have many really good options ( albeit expensive). If you research, you will realize that most companies will buy their panels and battery packs/powerbanks ( apple is one of them!!!), from China, and Brand Name them with their own and charge you a huge markup, or you can go online and do your homework= learn about exactly what you need and buy a nice setup from Alibaba/Ebay for a reasonable price.
Solar is awesome. Unfortunetely brands like Goal Zero market their stuff as the best, but their gear is overpriced to the max, heavy and VERY impractical for all hikers bar car campers ( IMHO!).
Research, research, research. Learn how Photovoltaics work etc, then you will realize that you can get great free energy for an initial low cost, or you can be a sucker and believe some of the manufacturers that will sell you underpowered products and you will just walk away mad and disgruntled and think Solar is still a joke - which it isn't!.

Tony Fleming
(TonyFleming) - MLife

Locale: Midwest
Solar Options on 03/24/2013 20:58:37 MDT Print View

Matt Hoskins,

If you're out there, would you mind sharing more specifically what you bought as a solar solution?

Thank you,

Tony Fleming

Vince Contreras
(pillowthread) - F

Locale: like, in my head???
+1 to fold-ups and battery bank... on 03/25/2013 11:04:40 MDT Print View

^^^^this. I use an old brunton panel and one of the bajillion batteries available on amazon. If you have more than one device to keep powered, go with a 20 watt panel and a 10,000mah battery; if not, than less.

Joseph Brody
Blackburn Flea Solar Charger on 08/21/2013 22:04:05 MDT Print View

Anyone try the Blackburn Flea Solar Charger?

It works to charge a LED bike light.

 photo photo14_zps1f60f59c.jpg

Edited by Killroy1999 on 08/21/2013 22:08:07 MDT.

Lowell Mills
(FarmHand357) - F
iPhone 5 off when charging to obviate need for external battery? on 08/22/2013 13:29:55 MDT Print View

I have a folding 12W solar array and use a 12V automotive-plug-to-USB adapter (the 5V, 2.1A kind). I noted that it would charge my iPhone 5 directly, unless a cloud passed by, which would kick it into the mode of telling me that this was not the correct kind of charger. Unplugging and replugging it got it charging again until the next cloud.

Just wondering if once it starts charging, if I then shut it down, will it continue to charge but without the discriminatory circuitry that keeps stopping the charging when the direct sun is interrupted?

The reason I ask is this same panel seems to charge my MacBook Pro when it's asleep, even though the wattage is well below the 65W provided by its power supply...

David Thomas
(DavidinKenai) - MLife

Locale: North Woods. Far North.
Re: iPhone 5 off when charging to obviate need for external battery? on 08/22/2013 14:24:42 MDT Print View

>"which would kick it into the mode of telling me that this was not the correct kind of charger."

I get that with various marginal chargers, loose connections, and having too many apps running for some chargers to support.

Could there be an app that would clear that fault and let the phone try again to be charged? The only solution I've found is to unplug and replug the cord?

>"Just wondering if once it starts charging, if I then shut it down, will it continue to charge but without the discriminatory circuitry that keeps stopping the charging when the direct sun is interrupted?"

For some of my marginal chargers, I need to do that. If the iThing is off, it turns on when I connect the charging cord and often, quickly goes into "charging not supported with this accessory". I've had better luck having the iThing on, shutting down all apps, connecting the cord, and then quickly powering off the unit (just the quick, one-button push. Not the long-hold then thumb-slide shut down). Sometimes it still stops the charging before reaching 100%, but the above procedure gets me much further than leaving the unit on. So the discriminatory circuit still seems engaged, but by reducing the power draw of the unit, charging is supported for longer periods.

Lowell Mills
(FarmHand357) - F
iPhone 5 off when charging to obviate need for external battery? on 08/23/2013 11:01:19 MDT Print View

Interesting; thanks, David. I tested my phone last night by plugging it into a USB port, then doing the complete shutdown (holding down the top button until I can use the red slidey thing at the top of the screen to shutdown).

Of course, now I can't tell how quickly it's charging, but it would see that there's essentially no current draw in this mode and that it might consistently charge, even on a partly cloudy day.

I will try to set up this experiment; I would think this would be great if it eliminates the need for a buffering battery intermediary...

Joseph Brody
Going Solar Light on 08/23/2013 19:31:11 MDT Print View

I actually work at a Solar Company that makes roof top module, but no device chargers. I don't have solar module design experience, so I asked someone savvy today. He had a printer letter size module that is thin. Our product is a flexible laminate where silicon based solar is rigid and brittle, so our stuff can be a lot lighter and durable. The design is a nominal 5 volts and he said that with the performance of the cells, its possible to charge without any extra electronics.

Yet, its still to big and heavy compared to a little 35g battery that I have. I'n not sure what the power is, but I think it could be downsized. I would not want anything bigger than a postcard.

I think all I need is the battery for 6 day trips. I'm going backpacking, I don't need to be playing with electronics for a 5 day trip. Maybe for a 10 day trip next year.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Going Solar Light on 08/23/2013 19:44:54 MDT Print View

"Our product is a flexible laminate where silicon based solar is rigid and brittle, so our stuff can be a lot lighter and durable."

If your product is not silicon-based, then what is it?

The current types of solar chargers use either single-crystalline silicon (for high efficiency) or else amorphous silicon (for flexibility).


Joseph Brody
CIGS on 08/23/2013 21:30:56 MDT Print View

Bob, I'm talking about CIGS.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: CIGS on 08/23/2013 22:03:18 MDT Print View

So, what commercially viable solar charger products are there using this?


Joseph Brody
Global Solar on 08/24/2013 08:21:05 MDT Print View

This one is down 112 g, but still fairly big.

Edited by Killroy1999 on 08/24/2013 08:24:03 MDT.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Global Solar on 08/24/2013 08:46:54 MDT Print View

2 watts maximum output (400mA) is rather anemic.

For most backpackers the technology isn't there yet. Over the past 10 years I have spent nearly 1,000 days off the grid utilizing solar in my tent trailers, so I have a little bit of experience.

You might find this interesting. Solar for backpacking?

For thoughts on charging strategies and system sizing read this. RV Solar Systems

Keep in mind, I am not an advocate for things electronic when backpacking. But if I were, spare batteries or a battery pack would be my solution, given the current state of technology.

Edited by ngatel on 08/24/2013 08:47:46 MDT.

Zorg Zumo
(BurnNotice) - F
Re: Latest, Lightest Solar Charges? on 08/24/2013 09:19:11 MDT Print View

I used a Brunton Ember on my last trip. Charged my phone very fast. Weighs 142gm. Major downside is that it lacks any attachment points. It would be nice to have it on my pack charging while I'm hiking. Otherwise very simple use.

Joseph Brody
Re: Re: Global Solar on 08/24/2013 17:21:09 MDT Print View

"2 watts maximum output (400mA) is rather anemic. "

A USB only charges at 500mA. Of course if you are hiking, the panel is not going to be directly facing the sun(as mentioned in your link), but if you are carrying solar weight, it better be put to use on your pack all day when you don't have a full charge.

In the link the solar charger was used was 360g. I never play with that many electronics to want to carry 360g of solar charger. For that weight, I could carry enough battery's to charge 10 iPhones.

Joseph Brody
Re: Re: Latest, Lightest Solar Charges? on 08/24/2013 17:23:23 MDT Print View

The Brunton Ember charged your phone fast because it is a big battery. The solar is only good for 100mA max. I would call that anemic.

Edited by Killroy1999 on 08/24/2013 22:08:44 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Re: Latest, Lightest Solar Charges? on 08/24/2013 17:40:36 MDT Print View

Maybe solar works best if it charges a battery at whatever current it produces.

Then, use that battery to charge your device at the current required.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Re: Re: Re: Latest, Lightest Solar Charges? on 08/26/2013 21:43:23 MDT Print View

"Maybe solar works best if it charges a battery at whatever current it produces."

Not exactly. For most rechargeable batteries, there is an optimum charge current, and that is generally in the ballpark of one-tenth of the maximum available output current of the battery, but for ten times the time period. This varies from one battery chemistry to another.

Solar panels work best in charging batteries if you use a charge controller.


James Couch

Locale: Cascade Mountains
Re: Latest, Lightest Solar Charges? on 08/28/2013 09:44:13 MDT Print View

+1 Jerry!

In particular most smartphones need something in the range of 7.5v to charge, when they don't get that they disconnect. Solar panels fluctuate the voltage output depending on how much sun they are getting. Charging a battery that has an integrated controller is the answer, charge the battery during the day, use the battery to charge the phone at night.

Goal Zero is one company that seems to really have solar figured out.

Taylor B
(tboudreau) - F
Suntactics Charger-5 USB Solar Charger on 08/28/2013 10:23:20 MDT Print View

I have been very impressed with my Suntactics Charger as it has been very reliable, and definitely feels like it will hold up as the construction feels solid. I apologize for not having more detailed voltage and amperage information, but I have found Suntactics claims of charging an iphone 5 in 2 hours to be reasonably accurate with consistent direct sunlight. Additionally just taking the panel, 8.5oz is pretty reasonable for the right trips.

Zorg Zumo
(BurnNotice) - F
Re: Re: Re: Latest, Lightest Solar Charges? on 08/28/2013 12:14:31 MDT Print View

Perhaps that is because you don't understand the usage model: Deliver a lot of juice when you need it and then slowly recharge during the day when you don't.