The Best Portable Solar Panel Review

What is the best solar charger for your phone, tablet and other small electronics when off the grid? To find out, we took eleven contenders and put them in head-to-head tests. We compared them on the following categories: output power, ease of use, weight, and versatility. In the end we found big differences in the panels we tested. Some worked well for all our needs and some barely charged anything. We also found there is not one best panel for all needs. Read on to find out which is the best solar charger for your application.

You may also be interested in the related category: External Battery Review.

Read the full review below >

Review by: ⋅ Founder and Editor-in-Chief, OutdoorGearLab

Top Ranked Solar Chargers Displaying 1 - 5 of 12 << Previous | View All | Next >>
Our Ranking #1 #2 #3 #4 #5
Product Name
SolarMonkey Adventurer
SolarMonkey Adventurer
Read the Review
Video video review
Bushnell Bear Grylls SolarWrap Mini
Bushnell Bear Grylls SolarWrap Mini
Read the Review
Goal Zero Nomad 13
Goal Zero Nomad 13
Read the Review
Video video review
PowerTraveller SolarGorilla
PowerTraveller SolarGorilla
Read the Review
Instapark Mercury 10
Instapark Mercury 10
Read the Review
Video video review
Editors' Awards  Editors' Choice Award  Best Buy Award  Top Pick Award    Best Buy Award 
Street Price $130
Compare at 1 sellers
Varies $55 - $60
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$160
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Varies $207 - $229
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$70
Compare at 1 sellers
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100% recommend it (3/3)
Pros Light, simple, charges tablets, internal battery, good low light performance.Light, inexpensive, simple, internal battery.Very robust and versatile, well integrated with other Goal Zero products.Light, simple, charges tablets, internal battery, good low light performance.Light, inexpensive, simple, can charge two devices at once.
Cons Can't charge multiple devices.No cigarette lighter adapter, only charges USB devices.Heavy, expensive, only one USB port.Can't charge multiple devices.No cigarette lighter adapter: only charges USB devices.
Best Uses Backpacking, sailing, hiking, car camping.Backpacking, sailing, hiking, car camping.Backcountry travel where you need serious power, car camping, sailing.Backpacking, sailing, hiking, car camping.Backpacking, sailing, hiking, car camping.
Date Reviewed Mar 17, 2013Sep 19, 2013Apr 30, 2013Apr 30, 2013Apr 30, 2013
Weighted Scores SolarMonkey Adventurer Bushnell Bear Grylls SolarWrap Mini Goal Zero Nomad 13 PowerTraveller SolarGorilla Instapark Mercury 10
Output Power - 30%
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Ease Of Use - 20%
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Weight - 30%
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Product Specs SolarMonkey Adventurer Bushnell Bear Grylls SolarWrap Mini Goal Zero Nomad 13 PowerTraveller SolarGorilla Instapark Mercury 10
Size folded (inches) 6.75 x 3.5 x 0.8 4.5 x 1.25 x 1.5 10.5 x 9 x 1.5 10.5 x 8 x 0.75 9 x 6.5 x 1
Panel Size (watts) 3 5 13 10 10
Max Output Power (watts) 3.5 4 13 10 10
Max Output Current (amps) 0.7 1.0 1.0 0.5 0.57
Internal Battery Yes yes Yes No No
OGL Weight (LB/KG) 0.6/0.260 .25/.11 2.0/0.9 2.0/0.9 1.2/0.54
Charge iPhone/smartphone yes yes yes Yes Yes
Charge tablet Yes Yes Yes Yes Yes
Charge laptop? No No Yes Yes No
Direct USB Plug? Yes Yes Yes Yes Yes - 2
Daisy Chain? No No Yes No No
12-Volt cigarette adapter No No Optional Yes No
Warranty 1 year 1 year 1 year 1 year 1 year

OutdoorGearLab Editors' Hands-on Review



Would you be better served by an External Battery
Before we get into this review, we want to highlight that many people may be better served by an external battery. External batteries often charge a smartphone 3-6 times, can be used when its not sunny, are compact and usually cost a fraction of the cost of solar panels or solar panels with built in batteries. If you only need 3-6 charges of your device, we recommend checking out external batteries. We have a complete External Battery Review.

Click to enlarge
Clockwise from upper left: Joos Orange, SolarMonkey Adventurer, Goal Zero Nomad 13, and Goal Zero Nomad 7.
Credit: Chris McNamara

Output Power: Watts Up?
In our past reviews, there was a high correlation between the watt rating and the highest output power. A 10-watt panel was generally about two times more powerful than a 5-watt panel. This is because they all generally had output power similar to the highest power rating of the panel. Things have changed. In our last round of tests you really need to look at the output power more the total power rating of the panel.

This is a little confusing so here is an example:
The SolarMonkey Adventure and Joos Orange are only rated 3 watts and yet both were able to charge iPads and reliably charge iPhones. The Goal Zero Nomad 7 has a watt rating that is 2+ times higher (7 watts) and yet could not charge an iPad and ran into issues when charging our iPad mini and iPhones. Why? Even though the Nomad seven is a 7-watt panel, the max output power using the USB connection is only 2.5 watts. The max output power of the Solarmonkey is 3.5 watts and the max output power of the Joos is 5+ watts.

The bottom line: the watt rating of the panel is not the only thing to consider. You also need to look at the max output power. See our spec sheet for which types of devices you can charge with each panel.

The Goal Zero Nomad 13 had the highest output power of all the panels we tested. Right behind it was the PowerTraveller SolarGorilla. Both were the only panels that could charge a laptop. Behind those was the Instapark Mercury 10. This was one of the few panels with two USB outputs. If your main goal is to charge two phones and/or tablets, this was an incredible value. Also of note was the Joos Orange. This panel has a low watt rating but its output power was quite impressive. It charged smart phones as fast or faster than any other panel we tested.

Ease of Use
Ease of Use mainly rates how easy it is to connect the device you want to charge. Panels with one or two direct USB plugs scored the highest. Panels that require that you keep track of additional cables scored lower. In this round of testing, we were happy to see that more and more panels have direct USB plugs. This means that the panel can be easily shared with multiple different devices and smart phones. All you and your friends have to remember to bring is a charging cable. In contrast, some panels show up with so many adapters that it looks like a socket wrench set (and requires near OCD skills in keeping everything well-organized.).
Click to enlarge
InstaPark Mercury 10 solar panel with two USB ports and a generous pocket.
Credit: Chris McNamara
In addition, we like panels that have a built-in pouch in which to keep your device and USB cable. For example, the Instapark 10 comes with two USB ports and a generous pocket that holds your phone, extra battery (optional), and USB cable. It also comes with little strings at the corners that allow you to hang the panel from bushes or hooks.

A panel like the Joos Orange gets a mixed ease-of-use score. There is no direct USB connection, so you have to always remember the Joos cord and an adapter and possibly your USB charging cable. On the other hand, it was the only panel that is self-supporting and can be easily oriented perpendicular to the sun.

Weight
Weight gets high weighting in our scores. After all, the whole point of a portable solar panel is to be, well, portable. A panel that weighs less than a pound and is very compact is generally all we take for most outdoor situations: hiking, backpacking, biking and climbing. If the panel weighs more than a pound and a half, it really needs to do some heavy duty charging of multiple devices and/or a laptop.

Also, consider that weight will increase if you need to bring multiple charging cables and/or a case. The weights in our spec sheet only include the weight of the panel.

The clear winner here was the SolarMonkey Adventurer. It is not only light, it is also very compact. It fits in most jacket pockets and barely fit in our blue jeans pocket.
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The SolarMonkey Adventurer just barely fits in a jeans pock for charging while walking. It easily fits in most jacket pocks.
Credit: Chris McNamara

If you are boating, weight doesn't really matter. Take that into account when looking at the scores.

Versatility: How many devices can you charge?
Versatility matters greatly to some and not at all to others. If all you need to do is charge a cell phone, then don't pay as much attention to the versatility score. You mainly just want a lightweight device with a USB output that is simple and easy to use.

However, if you want to charge multiple devices and bigger devices like a laptop, then versatility is much more important. The Nomad 13 is the highest rated in this category because it can charge so many different devices. If you have other Goal Zero batteries and lights it can charge even more. It was also one of the few panels that can be daisy-chained with others. Right behind it was the SolarGorilla. This panel can charge just about anything, including a laptop. The downside to this panel is that it only charges one device at a time. The Joos Orange was the most versatile small panel. It can charge just about anything short of the laptop and was the only panel to be water resistant and has a hole that allows you to lock the panel up. The Joos is also the only panel with replaceable battery.

Home Solar Panels
The world headquarters (AKA my house) of our sister site, SuperTopo.com, just went solar. Check out this detailed guide on how to choose home solar panels. The article contains photos, video, and many external links to help you evaluate if going solar is right for you.

Accessories
Many people choose to combine a solar charger that doesn't have an internal battery with an external battery. This allows the panel to charge the battery during the day while the device is being used. Then the device can be charged at night from the external battery. We recommend the Anker 2nd Gen Astro2 9000mAh and the RavPower Luster Mini 3000mAh for this use. For a full list of all the external batteries we reviewed check out The Best External USB Battery Review.

The Bottom Line
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SolarMonkey Adventurer in the included case.
Credit: SolarMonkey

Editors' Choice
The SolarMonkey Adventurer wins our top honors because it is the best choice for charging a cell phone or tablet, which is what most people need. It is very light, compact and comes with an internal battery. While many panels require you to keep track of multiple adapters and tables, with the Solar Monkey you just bring your device and its charging cable and you're good to go. There is also the big bonus of being able to clip this on the outside of your pack or generally suck up power during the day (while you are working on your phone). Then plug in your phone at night and grab power from the battery.

Best Buy
Click to enlarge
When the InstaPark Mercury 10 is paired with an external battery, it's by far the best value in a panel and battery combo.
Credit: Chris McNamara

The Instapark Mercury 10 is by far the best deal in a portable solar panel that delivers 10 watts of power. No other small panel came close to matching its versatility, ease-of-use, and price. If your main need is to charge a cell phone or small electronic devices, get this panel. When combined with a $30 external battery, you can get a phone and tablet charging powerhouse for under $100. This was one of the few panels with two USB charging ports. It has one of the most generous external pockets for holding your phone, cables and an extra battery. The downside to this panel is you can't plug in a barrel adapter for charging anything that needs a 12-volt (cigarette lighter) connector.

The Bushnell Bear Grylls SolarWrap Mini is the best compact panel. It is the most light weight and compact panel we tested, and comes with an internal battery to charge your devices even when the sun is down.

Top Pick: Best Panel for More Serious Charging
Click to enlarge
Goal Zero Nomad 13 Panel
Credit: Goal Zero
The Goal Zero Nomad 13 is the best for charging a laptop, multiple devices, and incorporating with other batteries and accessories. If you have serious charging needs but still need a portable solution, this is the panel to get.

Special mention: the Joos Orange is the most weather resistant panel we tested. If you're using your panel mainly in marine settings or want to leave your panel out where it might rain, this is a great option. It may win an award in the future if we determine that the reliability problem it has with its charging cable has been resolved.

Ask an Expert: Patrick Sherwin
Patrick Sherwin has been an innovator in the solar industry for the last 15 years. He's a LEED and NABCEP certified installer and owns his own solar panel installation company, has developed solar integrated electric vehicle charging stations, and has spent over two years living off the grid in the Bahamas and Ohio. His latest invention, the Go Sun Stove, is a high-efficiency portable solar cooker that uses nothing but the sun's rays to bake, boil, or stew your food. Patrick shared his expertise on how to choose the best solar setup for your needs.

What's the longest amount of time you've used a portable solar charger for?
The longest I've lived off the grid expedition style was a two month trip down the Amazon River in Peru. We used a Brunnto SolarRoll Solar Panel to power our trip, and that kept our satellite phone, laptops and camera batteries charged for weeks at a time.

How do you figure out what size panel or system you need?
I rarely say this in life, but in the case of solar charging I do think bigger is better. You might only want a system to charge your phone, but then out in the field your buddy needs his phone charged too, so now you need double the capacity. Then you might buy a rechargeable headlamp and start growing in your consumption. So you want to try and size it right from the beginning.

First, calculate how many appliances you want to charge, say a phone, a camera, and two flashlights, and then calculate the wattage needed to charge them. Once you know how much it takes to charge those four appliances, you need to keep in mind that the system's ratings are what could happen in the ideal scenario, but how often are you operating in those perfect conditions? It might be 5 pm, or it's partially cloudy and the panels are super dusty and muddy, so maybe you actually need double the wattage. That's why it's always important to go bigger.

You then need to consider how many days you will be out relying on the charger, and you can also add in the metric used in off-grid system design, which is 'days of autonomy,' or how many days you might go without any input from the sun. Days of autonomy depend heavily on where you live. In Ohio, when I do off-grid design I calculate three days, but in the desert southwest you can generally just use one. The longer you plan to be out and the more days of autonomy that you add, the more expensive and heavy your battery system is going to be.

What features do you look for in a portable charger?
I prefer using the mono and multi crystalline technology over the amorphous thin-film designs. The crystalline panels are a more proven design, more efficient, and generally take up less space. Another reason I prefer the more rigid and/or foldable panels is because the surface treatment of the cells can be rigid as well. Flexible surface treatments, like on the roll-up models, can delaminate over time, and are more difficult to clean because they are rubberized. Foldable panels can be just as lightweight as a rolled up one, because it takes less surface area to generate the same amount of power. Finally, crystalline panels have a lower per/watt cost than thin-film ones, but while they can handle some impact, if you crack the cell they won't work anymore.

The user interface is also key, and that technology has improved a lot over time. Ten years ago they had a bunch of alligator clips and loose wires, and it was a very backyard do-it-yourself ethic. Wires would often spark when plugged in, which wasn't dangerous but definitely disconcerting to a novice user. This is where companies like Goal Zero have done a great job of creating user centered modules that are much more plug and play.

What determines the efficiency of a panel?
Efficiency is a rating of how much of the sun's input a panel is capable of converting to energy. It just so happens that peak sunlight produces about 1000 watts per square meter. That is a universal constant at high noon in July, and that is the standard test conditions that manufacturers run from, but that is not the reality all the time. The efficiency of this kind of micro solar really tends to vary a lot, and is determined by the cell technology, or the silicone's ability to convert sunlight into electricity, and then the efficiency of the entire assembly.

For mono and multi crystalline panels, the average efficiency is about 15%, with 20% being the high end. Then there is an entirely different style of panel, which is the amorphous silicon or thin-film design. The amorphous silicone allows the photoactive layer to be 'painted' on the base layer, which can be a flexible material. This helps to create a more portable unit, but it is not as efficient as the rigid style, typically only getting around 8%.

So you would need about twice the surface area of thin-film solar to produce the same power as a rigid panel. This is generally not that big of an issue when talking about a household array or a solar field, because there is a lot of space, but in the portable world you want something that's lightweight and easy to transport. Figuring out how to created foldable panels of crystalline cells was a huge advancement over the thin-film design, because now you can have an efficiency of 15% in the field.

Would you recommend buying a unit with an external battery? Or just going with an external battery instead of a solar charger?
It is really smart to have the battery integrated into the design. It's not critical, but when you are buying a system it is important to consider the loads what are you powering, for how long and when (what time of day). This is the basis of off-grid design. When you are living off the grid the reality is that it's not about living off solar, it's about living off battery. I would recommend getting an integrated system where the battery and panels are matched to each other to cooperate consistently. Then what you really work towards is powering the battery, which becomes the hub that you can pull energy from when needed.

In many cases you can size an external battery to suit your needs instead. I carry around a lithium ion battery that can charge my phone three times, and it only weighs a pound. So I can power that up during the day with a 10 watt solar panel, and charge my phone off of that.

In our testing, we found that some of the ratings did not correlate with the actual power output. Why is that?
The misleading thing with solar panels is that they will create voltage very easily and under minimal light conditions. When manufacturers are rating panels they might have more emphasis on flash testing, which will produce misleading results. Testing devices can measure how much voltage is created by the cells, and then the watt rating is determined by multiplying it by the amperage, or current, but if the amperage is over estimated then the overall rating will be skewed.

The panel might create a high enough voltage to charge your phone, but there might not actually be enough current to make that happen due to the small size of the unit and also the efficiency of the panel. So it's easy for manufacturers to convince folks based on their testing procedures that a panel produces 8 watts when in reality it never makes that much.

How important is it to properly orient your panel and what's the best way to do so?
It is really important to get your right orientation. You have to make sure that you are perpendicular to the sun within plus or minus 20 degrees, and that's called the tilt angle. The other angle is east to west, called azimuth, which is equally important. Both of these angles are hard to achieve when you are travelling and moving. Getting the right angle is a critical issue when winter camping, as you have to really get a steep tilt angle in order to capture sunlight. It is less of an issue in summertime travel or tropical locations, when orienting it horizontally is just fine, as you will likely fall into that 20 degree window or so.

You rarely want to put the panel in a vertical position, say hanging off a table or a backpack. You almost always want to put it horizontally, except in winter months when the sun angle is super low.

One design feature is that a panel will have hooks that you can use to attach it to your pack when hiking. Are you realistically going to get much charge from that?
Probably not much. Maybe if you have a smart battery that can handle constant changes in voltages. I think you are better off putting it on the brain of the backpack, on the very top where it's mostly flat. In all honesty, I'm not really feeling this whole wearable solar trend. The production is just so minimal.

What sort of maintenance do you need to do to increase the charging performance and longevity of the panel?
Keeping the panel clean is very important, particularly on the surface that's collecting sunlight, and to do that you should use a non-abrasive cloth and cleaning solution. A little dust might only give a 5% reduction in performance, but if it's covered with mud then it's not going to work very well. Dust and dirt are your main maintenance concerns.

There is the potential to have some corrosion on your connectors, and so you want to keep an eye on that. An easy way to deal with corrosion is to use a little sandpaper to clear it out.

Any good solar energy stories you want to share with us?
During my expedition in the Amazon, we ended up at a remote ranger station, called a 'point of vigilance' against illegal logging. The station was being threatened by illegal loggers who were taking old growth trees from very remote parts of a protected area of the jungle, and the rangers were having trouble communicating via radio to their main office. They were worried that they were going to get ambushed and would have to abandon their post for their own safety. When we arrived, we had some tools with us and we took a look at their solar system, and sure enough so much corrosion had built up on all the terminals and all the terminations that it was probably running at only a quarter power. We rewired their system, cleaned it up and got it running, and they maintained their point of vigilance.

History of Solar Chargers
Humans have been trying to harness the power of the sun for millennia. 2700 years ago we were using magnifying glasses to start fires, and yes, burn ants, and the use of passive solar technology has been recorded throughout the ages since. The ability to turn the sun's energy into electricity was first discovered in 1839 by a French scientist name Edmond Becquerel. He found that when he place two metal electrodes in a conducting solution and then exposed it to light, electricity generation increased, and he dubbed this 'the photovoltaic effect.' It still took over another century for the modern silicon based photovoltaic (PV) cell to come into being, thanks to work done at Bell Labs in the 1950's, and the technology was quickly adopted by the space industry for use on satellites. At that time, it cost around $200 to produce 1watt of power, a staggeringly high number.

The 1970's saw greater use of PV cell technology thanks to a decrease in costs and oil insecurity. The first homes that ran on solar energy were built, and 'thin film' solar cells were developed. In the 80's and 90's the first large scale solar power plants were constructed, and solar panels started to appear all over, from experimental cars and planes to the basic calculator that every kid took to school. As the efficiency of PV cells increased and the per/watt cost continued to decrease, household solar arrays became more frequent and some do-it-yourselfers were fashioning their own solar chargers using single panels and car batteries. In fact, keeping a car battery topped off was one of the original consumer demands for this technology, and solar battery chargers are still commonly sold today.
The other demand for portable solar came from the outdoor industry. As our use of electronics in the field increased, such as satellite phones and laptops to update expedition blogs, so too did our need to power them. The first portable commercial solar chargers came on the market a little over a decade ago. Brunton was an early adopter of the technology, though their first chargers were more rudimentary and required a bit of electrical know-how. The first computer laptop solar charger debuted at the Consumer Electronics show in 2008, with a 15 watt panel that could charge a standard laptop in a few hours.

Goal Zero revolutionized the solar charger market when it launched in 2009, with an emphasis on design, ease of use, and humanitarian focus. While solar chargers might be a niche camping or survivalist trend in North America, in the developing world or in disaster relief situations it has lifesaving implications. Goal Zero has donated hundreds of thousands dollars' worth of merchandise to people afflicted by large scale disasters, such as the earthquake in Haiti in 2010, the Japan earthquake and tsunami in 2011, and Hurricane Sandy in 2012.

Today, the use of solar energy continues to grow at an exponential rate. Over the last decade, global production has increased 53 times, from 3.7 gigawatts in 2004 to a staggering 138 gigawatts today. Costs have decreased to less than $1/watt for large scale productions and an average of around 5$/watt for household arrays, however portable costs are still in the $10-20/watt range. Though portable solar is still a small slice of the overall energy production, is does fulfill a critical need in many situations.

Chris McNamara
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