For a long time I was against the idea of buying a solar powered charger for camping. But then I saw a venomous viper 1 yard from my tent while wild camping with my 6 year old. I realized how much it would suck if my phone was dead and was unable to call the local police or rangers if she got bit.
So, as much as I am personally opposed to using your phone while in the outdoors (or any other device – seriously, you should be enjoying a good digital detox and not checking your email!), it is still good to have a portable solar charger to keep your phone juiced in case of emergencies. Likewise, photographers and people dependent on GPS for navigation will want a reliable way to keep gear powered. And I’m sure there are a zillion other good reasons to have a solar charger while outdoors.
- Do You Really Need a Solar Panel?
- Best Solar Chargers Reviewed
- How to Charge Devices with Solar Power
- How to Choose a Portable Solar Charger
Do You Really Need a Solar Panel?
Don’t get me wrong: portable solar panels are awesome and have come a long way. They’ve gotten smaller, more durable, and much more reliable.
But they still aren’t perfect.
You aren’t going to be able to strap a small panel to your backpacking, hike through a shady forest, and expect your devices to get fully charged.
I say this because you need to be realistic about what portable solar panels can do. If you just buy a cheap solar panel or one with under 5 watts, then you’ve just got dead weight and an expensive toy in your pack (some will argue that anything under 10 watts is dead weight).
For short trips where you aren’t using your devices much, a power bank might be enough to keep you charged (see my picks for best backpacking power banks). Again, that doesn’t mean solar panels aren’t great. But you will need to figure out your power needs, estimate how much charging you can do, and decide on the right setup. These are things that I’ll talk about later in this article.
Best Solar Chargers Reviewed
When choosing a portable solar panel, you’ll mainly want to look at:
- Wattage: This is how much power the solar panel can supply. Generally, you’ll need at least 10 watts for keeping phones and small devices charged.
- Weight: And how it balances with the wattage.
- Whether there is an integrated battery: If there isn’t a built-in battery, then you will only be able to charge devices directly. Or you will need to bring a power bank. Use the solar panel to charge the power bank and then the power bank to charge devices (read my post on best ultralight power banks).
- Brand: Make sure you choose a reputable brand. The cheap knockoff brands can’t be trusted to give accurate info. It’s worth it to pay an extra $10-$20 to ensure you get the advertised wattage.
- Output: If you want to charge multiple devices at once directly from your solar panel, then you’ll need a device which has multiple outputs, preferably at 1amps per outlet.
- Auto Reset: Some solar panels have a serious flaw. They will slow or stop charging if a shadow passes overhead. Auto reset means they start charging at full strength once the sun comes back.
If you aren’t familiar with these things, don’t worry. I’ll go over them at the end of the post.
Goal Zero is one of the most popular brands of solar panels for backpacking and camping. They have a lot of panels which start at 7 watts and go up to 400 watts. For backpacking and camping, you’ll probably need their 7 watt, 14 watt, or 28 watt solar panel.
Their portable solar panels are very reliable and have all the features you need for practical use, like auto reset. They are also great at directly charging most devices. This is because they use a technology which automatically matches the charge output to the device. This improves efficiency. A junction box tells you how intense the sun is and gives you an estimate of how long it will take to charge a device.
There are two outlets so you can charge two devices at once. Another major plus is that it’s waterproof rated to IPX6, which means you can fall in a stream and it will still work. 🙂
Note that Goal Zero solar panels don’t have integrated batteries. You can directly charge devices but will not be able to store power. Bring a light, powerful power bank like the Anker PowerPort Solar Lite so you have a way to store power for later. *Goal Zero also makes their own power banks.
Goal Zero also makes their own cool power bank called the Guide 10. It is only 2300mAh (which is enough for around 1/2 to 1 charge of a smart phone). But the cool thing about the Guide 10 is that it fits AA and AAA batteries. You can use it to recharge batteries. This means you don’t have to carry a separate power bank and battery charger.
The only main downside to Goal Zero solar panel kits is that they aren’t very lightweight. Still, they deliver a good amount of wattage per ounce.
Specs (for 14 watt panel):
- Watts: 14w
- Amps: 2.4
- Weight: 22oz
- Size: 12.1″ x 15.8″ x 0.1″ (solar panel unfolded), 12.1″ x 7.8″ x 0.5″ (folded)
- Auto Reset: Yes
- Integrated Battery: No
- Connections: 2
- Cost: $$ – Buy here
Best For: People with higher power demands who don’t mind carrying extra weight for reliability.
#2: Suntactics S14
This brand is best known for making ultralight solar panels for backpacking. It is only 7 ounces, which makes it one of the lightest per wattage available. Pair it with the Astro battery bank for a setup which weighs just 11.4 ounces total.
5 watts isn’t a lot of power, especially when you factor in all the loss you’ll have during cloudy weather. So, this is really only a suitable option if you aren’t using your devices much. They do have higher watt options, but these don’t have such a good watt/ounce ratio. Bring a power bank along in case you need emergency power on a cloudy day.
The Suntactics also has smart features like auto reset, a high waterproof rating, and durable design. It’s a bit pricy but worth it if you are trying to cut down weight.
- Watts: 5w
- Amps: 1
- Weight: 7oz
- Size: 6×6”folded, 6×11” open
- Auto reset: Yes
- Integrated Battery: No
- Connections: 2
- Cost: $$S – Buy here at best price
Best For: Thru-hikers who want an incredibly lightweight solar panel and don’t have high power demands.
The ECEEN is really well designed for outdoor use. It has pockets where you can keep your gadgets while charging, a built-in stand, straps, and is waterproof. The most standout feature of this solar charger though is that it is lightweight at just 9.3 ounces
The only major downside is that you aren’t going to be able to charge two devices at once quickly. The 2amps is for ideal conditions. Connecting two devices to the solar charge will have a maximum of 1amp per connection, but realistically it’s going to be a lot less.
- Watts: 13
- Amps: 2
- Weight: 9.3oz
- Size: 7×12.7” folded, 14×12.7” open
- Auto Reset: Yes
- Integrated Battery: No
- Connections: 2
- Cost: $ – Buy Here At Best Price
Best For: People who want a cheap solar charger that won’t weigh them down.
#4: Anker PowerPort Solar Lite 15w (Currently unavailable)
In pretty much every list of the top portable solar chargers, the Anker PowerPort Solar Lite takes the #1 spot. There is good reason for this. The solar charger is very reliable, doesn’t have issues with bouncing back to full charge after shadows pass overhead (auto reset feature), is pretty lightweight, durable, and a good value. It also comes in a 21w version if you need more power.
Some other perks of the Anker PowerPort solar charger is that it has elastic loops for attaching it to your pack and a pocket for holding your devices.
Note that this solar charger does not have an integrated battery. We recommend pairing it with the ultralight Anker Astro power bank (4.2oz) so you can store power. The total setup weighs in at 16.7oz.
- Watts: 15
- Weight: 12.5oz
- Size: 11×6.3” folded, 18.1×11” open
- Auto reset: Yes
- Integrated Battery: No
- Connections: 2
- Cost: $$
Best For: Changing devices quickly while camping, backpacking, or hiking
The Solar Paper by Yolk Station is marketed as the “world’s thinnest and lightest solar charger.” At just 0.4 inches thick, it really does live up to its promises.
In addition to being super small, the Solar Paper have some other great features like a 23.7% efficiency, auto reset (which is important for when those annoying shadows pass over and cause charge speed to reduce!), an LCD amp meter which shows charging speed, and waterproofness to IP64 rating. One panel is 5 watts, but additional panels can be easily added with a magnet system.
The only downsides of this portable solar charger is that it is fairly pricy, doesn’t have an auto-reset feature, and its bare design doesn’t have any straps. One panel will be enough to charge your phone. To charge tablets, you’ll need at least 2 panels.
- Watts: 5w (additional panels can be added)
- Amps: 1
- Weight: 4.8oz
- Size: 3.5×7.5”folded, 7×7.5” open
- Auto reset: No
- Integrated Battery: No
- Connections: 2
- Cost: $$$- Buy Here At Best Price
Best For: Lightweight backpacking and higher budgets
The company BioLite makes some really cool alternative-energy gear. Their solar panel is no exception. It is very small and pretty lightweight (considering that the battery pack is integrated). The little kickstand allows you to position the solar panel towards the sun easily. There is also a sundial so you can easily position it correctly to get the most sunlight.
Yes, it does take a while to charge with this tiny solar panel. However, it has good reviews overall and does its job well. You’ll be able to clip the solar panel to your pack during the day and then use the battery to charge your phone/device at night.
The downside of the BioLite solar panel is that it doesn’t have a lot of the features you’ll find in newer solar chargers, like auto-reset. The integrated battery is only 2200mAh, so it will only store enough power to charge your phone about 1 time.
- Watts: 5w (10 watt model also available)
- Amps: 1
- Weight: 13.8oz
- Size: 10.1 x 8.2 x 1.0 inches
- Auto Reset: No
- Integrated Battery: Yes – 2200 mAh
- Connections: 1
- Cost: $$- Buy here
Best For: When you won’t be carrying a separate power bank.
As mentioned before, you might not even need a solar charger for shorter backpacking or camping trips. Often, a power bank is enough to recharge your devices (assuming that you aren’t using a lot of high-power devices).
This solar power bank has a large capacity of 25000. That’s 10x more than most portable solar chargers. It will charge an iPhone 7 nearly nine times.
Since the solar panel is tiny, it will take forever to recharge the power bank. At a conversion rate of 200mAh per hour, you’ll need 12 hours of sunlight to fully charge the battery pack. And that’s assuming optimal sunlight! Also remember that power banks don’t get their advertised capacity, and that capacity can drain over time. So, be realistic about how well this will serve you on your trips.
I wouldn’t recommend this for long trips. However, it’s a great solution for shorter trips where you want a way to charge devices “just in case” the power bank drains.
It also has a built-in flashlight. This feature is really unnecessary for backpacking, but is nice if you want something for emergency preparedness. After a recent flood where I live, I got one of these to keep with my emergency supplies. I recharge it occasionally to make sure it stays topped off. Yes, I am turning into a prepper! 😮
The downside of such a huge capacity power bank is that it is heavy! It is definitely not suitable for thru-hiking, but would be great as a backup power source for multi-day backpacking trips – especially if you use your phone often.
*There’s also the BLAVOR solar charger. It only has 10,000mAh capacity, but is lighter weight at 8.5oz.
- Amps: 2.1
- Weight: 15.5oz
- Size: 7.5 x 3.9 x 1 inches
- Connections: 2
- Cost: $ – Buy here
Best For: Short trips where you want to have a backup solution, or for emergency preparedness.
How to Charge Devices with Solar
There are a few ways to charge devices with solar panels. Each method has its own pros/cons and setup requirements.
*I personally recommend option 2: getting a solar panel without an integrated battery and bringing along a power bank. In the field, you can then either charge your devices directly (for maximum efficiency) or charge a power bank that you bring along (so you have power for later).
Option 1: Directly Charge Devices from the Solar Panel
Most portable solar panels don’t have built-in batteries. To use them, you simply plug your device into the solar panel, put the solar panel in the sun, and let it charge the device.
Because there is no integrated battery, these solar panels are lighter weight. For people like me who have to carry everything on in their backpack (including my daughters’ gear!), every ounce matters.
The main benefit of directly charging is that it is more efficient. When you use the solar panel to charge a battery and then charge a device, you lose some of the power. It’s lost through the cables, conversion, and through the battery. By directly charging your devices, you will get the most power from the solar panel. There also isn’t any issue of your device discharging back into the solar panel.
The main issue of not having a battery is that you have no way of storing power. So, if you need to charge your device and it’s a cloudy day, you are screwed.
Another issue with these solar panels is that if sunlight reduces during charging, the power output reduces – and stays at that reduced rate. That means a shadow passing over the charger can reduce output to practically zero!!
The problem is easy to fix: you just unplug the phone and plug it back in. Charging will resume at full capability then. However, it’s incredibly annoying to do this. It’s also incredibly annoying to come back to base camp after a long hike only to realize your phone hasn’t charged at all because a friggin’ cloud passed over after you left!
Many solar panels have an “auto reset” feature which ensures the panel continues to charge at full strength, even after clouds pass over. Be careful when choosing a solar panel as not all have this feature. Even popular models like the Poweradd 14 and Instapark Mercury 10 will stop charging when shadows pass over. It’s important to look for a solar panel which has “auto reset” feature By contrast, solar chargers like the Anker PowerPort Solar Lite will return to full charge once the shadow passes.
Another issue is that some devices require a certain amount of power before they start charging. Nokia phones, for example, require 120mAh to start charging. If you try to directly charge them with a solar panel on a cloudy day, you might not even get a trickle charge. You’d need a very large solar panel to charge in less-than-ideal conditions.
Another thing to watch out for: You may not be able to directly charge your devices with the panel. Check the compatibility, or you may need to get a charge controller to use with the panel.
Option 2: Solar Panel Plus Power Bank
If you need a way to store power, then this is probably the best solution. You get a solar panel without an integrated battery and bring your own power bank. You’ll have a lot of flexibility in choosing the size of the solar panel and capacity (mAh) of the power bank.
You can use the solar panel to directly charge devices, which gives you the most efficiency. Or you can use the solar panel to charge the power bank so you have juice for cloudy days. You lose some of the power in the conversion from power bank -> device, but at least you have backup power.
Of course, you can charge the power bank before you leave for the trip and when you are in town/refueling. That means you don’t have to rely completely on the sun for powering devices.
Most power banks are really heavy, but there are some lightweight options. The Anker Astro battery pack, for example, is lightweight at 4.2oz and could charge an iPhone 6 nearly two times.
Note that the power bank solution isn’t perfect. Let’s say you plug your phone into the charged power bank. Once the phone battery is charged, the device battery might start discharging back into the power bank! You’ll need to get a power bank that prevents this. Or make sure to monitor your devices and unplug them when the battery is full.
Option 3: Solar Panels with Integrated Battery Packs
These solar chargers have a battery in them. First you charge the battery, and then you charge your device with it. Solar power banks (power banks with tiny solar panels built into them) also fall into this category.
Having a battery means you can store excess power, which is a lot more reliable. You are even able to charge the solar panel’s battery before you leave, so you start the trip with power (of course, you could do this with a power bank too).
The main benefit of using a solar panel with an integrated battery is that there aren’t any issues with shadows disrupting charging speed. You usually don’t have to worry about any compatibility issues.
The main issue with solar panels with integrated batteries is that they are usually a lot slower on both ends. They are slow to charge the integrated battery, and then the battery is slow to charge your device.
Another issue is that there are not many options. There aren’t very many solar panels (at least good ones) that have integrated batteries. Even if you find one that does, it won’t necessarily have the right battery capacity for your needs. This makes it hard to find a solar panel with the exact specs and battery size you need.
The integrated battery also means extra weight. Carrying a separate power bank also means extra weight. However, the integrated battery often doesn’t compare to the backpacking power banks you can get which are highly efficient and have a lot of capacity per ounce.
Choosing a Portable Solar Charger for Outdoor Use
There are so many solar chargers out there now. Here, I’m going to focus on what you need to look at for outdoor use.
I’m also going to focus on solar chargers which are actually portable. That immediately eliminates a lot of “camping” solar chargers because they are designed for RVs and car camping. Some of those camping solar chargers are meant to power friggin’ TVs and weigh a ton!
Portable Solar Charger vs. Power Bank
As I mentioned earlier, portable solar panels are awesome, but they are often unnecessary on most short trips. Portable power banks can hold up to 25,000mAh without getting too heavy, which is plenty of power to keep gadgets like phones, camera batteries, headlamps, and GPS trackers charged.
However, power banks are a pain in the ass on longer trips where you will need to recharge frequently. As several thru-hikers mentioned about their experiences using a power bank, they had to recharge it when making rest/fueling stops in town. Since power banks take forever to recharge, you end up losing a lot of time. It forced them to stay in hotels to have a way to charge the damn thing, so ended up costing a lot of money too.
It really depends on how you are using your devices while hiking, camping, and backpacking though. Since solar powered phone chargers are getting so cheap, it might be worth it to have the reassurance of a more reliable power source than what battery packs offer.
- Day hikes: you probably don’t need any portable charger.
- Trips up to 3 days: You might need around 3,000 to 20,000mAh, depending on how often you are using devices.
- Photography trips: If you are staying in one spot, then a solar panel makes sense because you can capture maximum sunlight.
- Thru hiking: Calculate how long you will go before refueling. If you are refueling weekly, you can recharge the power bank in town – though it’s a pain in the ass to wait around for it to charge. A portable solar panel might make sense if you don’t want to recharge in town.
How Many Watts Do I Need?
Solar panels are rated in watts. This is a measure of how much power they are able to produce. Most portable solar panels range from 5 to 28 watts. Anything bigger than 28 watts is probably too large to consider “portable.”
Watts = Volts x Amps
Volts: Volts is the energy potential of the charger. All USB cables run at 5 volts (thus anything that charges via USB takes 5 volts).
If you were to try charging your cell phone on a 12 volt solar charger, it wouldn’t be able to handle that much electricity. You’d see sparks and melting plastic! Luckily, we don’t have to worry about this happening because portable solar chargers designed for USB devices are standardized at 5 volt.
On the flip side, don’t try charging your phone on a solar charger with higher voltage! You’d need an adapter to do this safely.
Amps: The amount of electricity that can flow at once is measured in amps. Older cell phones will handle about 1 amp. Newer fast-charge phones will handle upwards of 2 amps. Devices which use more power (such as tablets) usually handle around 2 to 2.5 amps
Confused? A good way to think about watts is using a metaphor of water going through a pipe:
- Watts = total water
- Volts = water pressure
- Amps = size of pipe
If you have high water pressure (volts) and big pipes (amps), then you are going to have a lot of water (watts) going through the pipes.
Since we know that all USB solar chargers are 5 volt and most devices aren’t going to draw more than 2 amps at once, we can figure out how much watts we need our solar charger to have.
5 volt x 2 amps = 10 watts
Thus, 10 watts is the lowest you should look for in a portable solar panel. You can still charge devices with a lower wattage, but it might take forever — especially when conditions aren’t ideal.
Why You Might Need More than 10 Watts:
Bear in mind that the watts are listed for ideal sunlight and temperature. When the conditions aren’t ideal, you can get drastically lower wattage. For example, one member calculated this at a cycling forum:
a) Time of day means 10-100% potential efficiency in daylight. Say an average of 50%.
Clearness of sky means 0 to 100% efficiency, say an average of 50%
Aim of panel means (for a panel strapped flat onto a bike carrier) 30 to 80% at this latitude, say 55% average.
b) There is a converter circuit pushing the current into the battery. Even with a 5 or 6V input the converter efficiency will be between 70 and 95%, say an average of 85%
c) Power in vs power out of a good battery is typically around 70% efficient.
d) The cache battery then charges the gadget battery as per b) so another 85% maybe.
e) Discharge of the gadget battery is again about 70% efficient.
When you multiply all these things together, you get a drastically reduced amount of power:
0.5 x0.5 x0.55 x .85 x 0.7 x 0.85 x 0.7 equals…… (drum roll) 048. Or about 5%!
Of course, you can avoid a lot of these losses by making sure to set up your solar panel so it is facing the sun and charging during peak sunlight hours. Even then, you still can’t count on the solar panel getting the amount of watts it is advertised.
The bottom line? Calculate at least 10-20% more power than you need. For charging a phone or GPS, you’ll want at least a 10 watt solar panel. In less-than-ideal conditions, you’ll want at least a 20 watt solar panel.
How Long Will It Take to Charge a Device with Solar?
How long will it take to charge with a portable solar panel? You will need to know two things: The amps of the solar panel outlets, and the size of the battery you want to charge.
Amps is a measurement of the output of the solar panel. Most portable solar panels have 1 or 2 amps.
If you are only charging one device with a small battery, then 1 amp should be sufficient. For newer devices or charging multiple devices at the same time, you’ll need 2 amps. Note that a lot of solar panels have 2 amps total discharge, but only 1 amp per outlet. So, if you only connect one device, it will charge at 1 amp and not 2 amps.
Some devices will only accept a 0.5 amps@ 5volts charge. That means it will not charge faster with a larger solar panel. However, assume that your solar panel will not be working at 100% efficiency. So, getting a larger solar panel could mean that you actually get that 0.5amps charge.
But, if your device has low amp potential, then getting a high-amp charger isn’t going to help it charger faster. Your phone can only charge as fast as its amp rating.
For example, as Techlicious explains, the iPhone 6 supports 1.6 amps and comes with a 1 amp charger. You could use a 2.2 amp charger with it – but it will still only charger at a maximum of 1.6 amps.
Milliamp Hours (mAh):
Phone batteries are often measured in milliamp hours (mAh). Or, sometimes they are listed in amp hours (Ah).
1 Ah = 1000 mAh.
This is a measurement of the battery’s capacity. A lot of people use it to gauge how long a battery will last. Some phones have really big batteries, like how the ZenFone 3 Zoom has an impressive 5,000 mAh battery. The LG X has a 4,500 mAh. Most newer phone batteries are going to have around 2,000 to 3,000 mAh capacity. Tablet battery capacity varies drastically from 5,000mAh to 20,000mAh.
Once you know the mAh rating of your battery, you can figure out how long it will take to completely charge. For example, if your solar charger is capable of giving out 1 amp of power, in one hour it will charge 1,000 mAh. A 3,000 mAh battery would take 3 hours to charge (assuming ideal conditions – which pretty much never happen).
Backpack Solar Chargers
A lot of portable solar panels come with loops or hooks so you can strap them to your backpack. In theory, this sounds like a good idea. You gather sunlight as you hike, right?
In practice, backpack solar chargers don’t work very well. The angle that they hang from your backpack means they don’t get direct sunlight. Further, if you are hiking towards the sun or in an area with a lot of trees, then you might get practically zero charging. Almost zero is still better than zero, but don’t expect to fully charge while you hike.
The bottom line: To get a good charge from your solar panel, you’ll need to set it up so it is facing the sunlight. Expect to set it up during lunch breaks while hiking.
Don’t even consider a solar panel for backpacking if it isn’t durable. It only takes a few bangs to crack some solar panels. Not to mention all the crashing around it does in your pack or those times you fall in a creek.
- Flexibility and Folding: When the solar panel is flexible or folds at multiple points, it will be able to take more of a beating.
- Waterproof: By their nature, solar panels are waterproof. What you want to look at is how waterproof the solar charger connections and batteries are.
- Panel type: As a general rule, monocrystalline solar panels are the most durable and rugged. However, they are also the heaviest and thickest. CIGS panels (thin film) are next, followed by Polycrystalline
Good brands of portable solar chargers will list their efficiency rating. Anything above 22% is a fairly good efficiency. Yes, just 22%!
Aside from the manufacturer’s listing, you can also determine solar charge efficiency by looking at:
- Panel type: Monocrystalline solar panels are the most efficient followed by polycrystalline and CIGS.
- Panel surface area: The larger the solar panel, the great its surface area and the better it will be able to convert solar energy into power. You’ll really see the difference in efficiency when the sunlight is less than ideal, such as on cloudy days.
Number of Connects and their Amperage
If you just need one connection for your solar charger, then choosing one is easy. Things get complicated when you need more than one connection port.
As mentioned before, the reason is because most portable solar chargers list their TOTAL amperage for ALL connections. Let’s say you want to charge 2 power-thirsty devices on a 1amp solar charger. The solar charger splits the amps between the connections, so they both charge slowly.
Some devices won’t even start charging unless they can get a certain amperage level, so having multiple connections could backfire on you!
By contrast, some solar chargers list the amperage of EACH connection. Or, some solar chargers even have connections which have higher amps than others so you can put your priority device to charge there and leave the other device for the slower connection.
To figure out the value, look at the price per watt of the solar charger.
Total price divided by watts = price per watt.
Portable solar chargers are getting cheaper all of the time. It used to be that $10 per watt was a good deal. Now you can find quality portable solar chargers that cost less than $3 per watt.
Do you have a solar charger for camping, hiking, and backpacking? Which one and how do you like it?
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