I am a big advocate of digital detoxing. So, when I go backpacking, I will turn my phone off. However, I can respect that there are plenty of situations where you’d need to use your phone – like when you are using your phone as your main camera, or you need to call for emergency assistance. It’s reasons like these that solar phone chargers are so useful.
This is a very affordable power bank with an integrated solar panel. It doesn’t have pack in as much power per ounce as some ultralight power banks, but it does have a built-in solar panel. The tiny solar panel will take forever to recharge the battery, but is good for when you need emergency power.
- $ – Buy Here
The Suntactics is an ultralight 6w solar panel. Pair it with the ultralight Astro E1 power bank and you’ll have a complete power solution for devices in the field.
- 6 watt solar panel
- 6,700mAh power bank
- Total weight 11.4oz
- $$$ – Get the solar panel here and power bank here
Keep reading for recommendations and advice on how to choose a solar phone charger.
- Using Solar to Charge Your Phone
- How Much Capacity Do You Need?
- Types of Solar Phone Chargers
Using Solar to Charge Your Phone
Solar power is awesome, but it often gets hyped up. In reality, solar panels won’t capture as much light as they promise, and you’ll be lucky if you get 3 hours of good light in some parts of the world.
For shorter trips, or on trips where you can refuel often, you are probably better off bringing a power bank. Power banks come in high capacities. It’s common to find power banks of 20,000mAh – enough to recharge your iPhone X approximately 6 times. When you calculate power/ounce, the power bank often ends up being the lighter solution. You can check out my upcoming article about the best lightweight power banks.
But there are some situations where solar makes sense as a portable charger.
- You won’t be able to refuel often.
- You use your phone a lot, such as a GPS tracker and camera.
- You also want to charge other devices.
For short trips, I’d recommend getting a solar power bank. You get the ease that comes with a power bank, but can still use solar to recharge it in an emergency situation. The Blavor power bank has a capacity of 10,000mAh and weighs 8.5oz.
For longer trips or if you have higher power demands, I’d get a portable solar panel plus power bank. The setup will weigh more and means more stuff to carry, but it’s more reliable. The Suntactics weighs just 7oz and has a max of 6 watts. Pair it with the ultralight Anker Astro E1 power bank.
How Much Capacity Do You Need?
Capacity is measured in milliamp hours, or mAh. Let’s say that you only need a solar charger for your phone. Here’s how to figure out capacity needs.
A typical smartphone battery has a capacity of around 3,000mAh when new. As it ages, you’ll lose approximately 20% of that. So, let’s assume that your phone battery requires 2,400mAh to fill (you’ll need to check the numbers for your phone).
Now, figure out how long it will take to drain your phone battery. If you only use your phone for taking photos and occasionally making calls, then the battery will last around 10-24 hours. You can make your battery last by reducing brightness, turning on airplane mode, and these tips.
That means you will need approximately 2,400 to 5,760mAh per day. Calculate this by how many days you can go between recharging your power bank. For a 3 day trip, for example, you’d need a 7,200 to 17,280mAh. However, if you keep your phone turned off for most of the time, you might need less than 3,000mAh of power.
This can vary drastically depending on your type of phone, how often you use it, and even things like the quality of your cables.
To calculate mAh requirements:
- Check your phone’s battery capacity
- Determine how often you’ll use your phone.
- Get it in “backpacking mode” by doing things like turning off unnecessary apps.
- Test how long it takes for your battery to die in backpacking mode.
Types of Solar Phone Chargers
Option 1: Solar Power Banks
When you only need the solar panel to charge your phone or maybe one more small device, then a solar power bank is probably the best solution.
A solar power bank is just a power bank which also has a solar panel on it. You can fill the power bank with a normal wall outlet before you leave for your trip. Use the solar panel to keep it topped off.
The major issue with using a solar power bank is that they have tiny solar panels (usually just around 7 inches long). So, they can’t capture too much sun. Even in direct sunlight, it will probably take over 50 hours to refill the power bank. Since you can probably get multiple charges out of a full battery, that translates into around 15 hours of sunlight to charge your phone!
- Come in many different capacities
- Usually will charge phones 2-3 times.
- Lightweight options
- Pre-fill power bank at home or in town
- Take forever to refill with solar
Option 2: Portable Solar Panels
If you are using your phone often or also need to charge other devices (like cameras and GPS trackers), then you’ll need a large solar panel.
Bear in mind that solar panels often aren’t as great as they get hyped up to be. You may only get 3 hours of good sunlight in some parts of the world. The cheap solar panels are often very inefficient (which is why it’s worth it to pay a bit more for a reputable brand).
Read this post on The Best Portable Solar Panels for Backpacking to learn more about the options.
- Can capture more power at once
- No need to wait in town to refill power bank
- Heavier setup
- Need to be paired with power bank/external battery
The Anker solar panel (shown above) is 15 watts and fairly lightweight at just 13.8 ounces. You can use it to directly charge your devices or to charge a power bank. Check it out here.
Solar Phone Charger Features
Be warned that the quality of solar battery banks varies drastically. Even the manufacturers know this and the cheap solar chargers will specifically state that it’s best to charge the power bank with a power outlet and the “solar charging feature should only be used as an emergency back-up instead of a main power source.”
The main things to look at when choosing a solar battery bank are:
How much power a battery bank can hold is measured in millamps. The higher the capacity, the more power the battery bank can hold.
To figure out how much capacity you need, look at the mAh of your phone’s battery. Then think about how many times you want the power bank to charge your phone.
- The iPhone X has a 2,716 mAh battery.
- In theory, a power bank with 10,000mAh capacity would be able to charge it 3 ½ times.
Unfortunately, you probably won’t actually get 3 ½ charges out of any powerbank. Why? Because no power bank is 100% efficient. A lot of power gets lost when sending it from the power bank battery to the phone’s battery. This has to do with the different voltage of the power bank and the phone. (Source)
Further, some power is lost through the connection cable. Temperature can also affect how much power is lost.
Expect a power bank to only deliver 66% of its listed capacity.
So, if a power bank has a 10,000mAh capacity, expect to actually get 6,666mAh – which means it would charge an iPhone X about 2.4 times instead of 3.5 times.
*To check the capacity of an iPhone battery, open up the settings app. Then choose “Battery,” “Battery Health” and look at the “maximum Capacity” indicator.
**Note that a battery’s capacity gets lower as it ages. So, a new battery might have a capacity of 3500 but shrink to 3100 after 6 months of use.
The amperage (amps) of a solar battery pack tells you how fast it can charge a device. Most solar chargers for phones will have 1 to 2amps. If you need to charge larger devices like laptops of tablets, you’d need something with higher amperage – and thus a bigger solar panel instead of just a solar power bank.
Watts tells you how much power the solar panel can gather. The higher the watts, the stronger the panel – but high watts also means that the panel will be bigger and heavier.
Don’t expect a solar power bank to have anything more than 1 to 2 watts. Yes, this means it will take a very long time to fill the power bank battery with sunshine. That’s why it’s recommended to fill the power bank with an outlet before you leave/whenever you get to town.
If you really need reliable power and faster charging, then you’ll need a portable solar panel and not just a solar phone charger. As mentioned earlier, I recommend the Anker PowerPort Lite. It is 15 watts and still very lightweight for backpacking.
Number of Outputs
A lot of the newer solar power banks now have two outlets. This allows you to charge two devices at the same time. This doesn’t necessarily mean you should charge two devices at once though, as this will significantly slow down charging time.
Solar power banks have all sorts of extra features like built-in flashlights, waterproof ratings, and so forth. But one feature which you will absolutely want is a carabiner hook. Otherwise, you won’t be able to attach the power bank to your pack. You’d have to lay it flat to charge, which means no charging on the go.
Best Solar Phone Chargers
Right now, this solar battery bank has the highest capacity available. At 25,000mAh, you will be able to recharge an iPhone 8 over 9 times. You might not even need to use the solar feature of it since it can keep your devices charged for so long.
The high capacity of it does mean that the RAVPower bank is heavy at 19.4oz. So, I’d only recommend this if you use devices very often during your backpacking trips and need to stay powered. Surprisingly though, the power bank can refill on solar fairly quickly. It will take around 85 hours to recharge on sunlight. Yes, that’s a long time – but battery banks with half the capacity often take that long.
- 25,000mAh capacity
- 7.13×3.5×1.18 inches
- 3 outputs
- Charges iPhone8 over 9 times
- IP66 waterproof rating
- Built-in LED light with 3 settings
- Buy here
RAVPower also makes a 15,000mAh solar charger which you can get here. It is lighter and smaller.
As far as cheap solar power banks go, this is one of the most popular and reliable. There are some nice features, like that the light indicator turns green when solar energy is being absorbed. It will charge even when there isn’t much light. And it charges devices quickly at 2.1amps. Instead of just claiming that it is “waterproof”, the waterproof rating has actually been tested.
Of course, it will take a long time to fill the battery with solar panel (about 56 hours in decent sunlight). But, this is actually better than most others in the same price range.
- 10,000mAh capacity
- 5.6×2.9×0.7 inches
- One USB output
- Wireless charging
- Fully charges in 6 hours via outlet
- Charges iPhoneX 2.3 times and iPhone8 3.5 times
- IPX4 waterproof rating
- Built-in flashlight and compass
- Buy here
Suntactics Solar Panel
Suntactics is very popular with ultralight backpackers because one panel only weighs 7oz. The panel actually performs very well and has all the features you’d want of a modern solar panel, like auto reset and durability.
There is no battery in this solar panel, so you’ll need to pair it with a power bank. Go with the Anker Astro (4.2oz) if you need something ultralight. For higher capacity, the Anker PowerCore Lite 10,000 and 20,000 are good options.
- 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