If you have ever bought or used a solar cell phone charger then you know about the frustration of getting a phone fully charged using these small solar panels. First of all most of these solar chargers are not rated properly as the manufacturers use the rating from STC (Standard Rating conditions) and use the max efficiency.
When you get to it in real world conditions the results are different from what the marketing department made you believe. However this does not mean they do not work. Understanding Solar panel efficiency, battery bank capacity and getting proper wattage can go a long way in helping you pick and use these devices properly.
But actually one of the main issues as to why solar Chargers don’t work is because when conditions for example in cloudy conditions change most chargers stop to work. They however don’t resume charging once when conditions improve and you may need to unplug your phone and plug it in again.
Our top pick is the Big Blue 20W Solar Charger. It is an an efficient 4 solar panel charger and has an ammeter that allows you to check the power output from the charger. This is important as the output changes over time and pluggin in your phone when may not really charge your phone when the output is low. A Smart Internal Chip detects the conditions to stop charging when conditions are low and resume once sunlight is sufficient. More on this below:
Picking a Solar Charger for your Phone
The wattage of the panels are indicated and this can guide you in choosing for the best use such as heavy duty or light, mobile ,and either single outlet or multiple outlets. A phone needs 3watts to 5watts of power to charge while an iPad would need around 11 watts.
However if you pick the 5 watts charger for your phone it may not be dependable as this will drop drastically due to inefficiency and wont fully charge your cellphone on cloudy days. Solar chargers are tested at STC (Standard Test Conditions) at a humidity of around 1.5 and ambient temperature 25 degrees Celsius and are flashed with 100 watt of light. These tests provide a theoretical maximum rating that will not simply work in real world conditions.
You need from around 2 to 3 amps of charge your phone at 5 Volts. To get the wattage of a Solar Panel you simply multiply the Rated Amperage with the Voltage.
Example 3A x 5V = 15 Watts
So theoretically you need a 15 Watts or higher to charge your phone. Dispersed light is better for solar panels than direct sunlight or sunlight at an angle and a panel can exceed 30% efficiency with dispersed light. Solar Panels can be used to charge all types of Rechargeable Batteries regardless of Voltage. A solar charger is easy to use and you have just to leave the charger around in the sun to charge.
Real Power Output
We tested the Nekteck Solar Charger on a clear day and we could only draw about 2.3 amps at around a voltage of 4.9v.
2.3 x 4.9 = 11.7 watts
So this gives around half of the rated output. The Nekteck is not a bad example but rather what you should expect from the ratings. The output also changes according to the angle of the solar panel, time of day and cloudy conditions.
While you are supposed to directly hook your phone directly to the solar chargers this is not recommended when conditions are not good. This is because every time the output goes up and down this activates the phones charging system which actually uses power. The best thing is to use a USB power meter to check the output and use it when it is at its peak or optimum for your phone.
Solar Charger Powerbank
They are two types of Solar Cell phone chargers you can get in the market. The Solar Charger is a type of direct charger is simply hooked to the phone to charge from the solar panels is channeled to the phone via USB cables. You just have to face the solar panels to sunlight and it will be charging your device.
A Solar power bank charger has a battery pack alongside the solar panels. You don’t have to hook your phone directly on the solar charger and you only charge from the battery bank. In most types the solar panel is quite small and solar charging is only as a backup option. It is important you charge the bank via an AC source.
Before you decide the power bank or solar power bank for mobile, you first consider the battery capacity of your phone. If you want to have an idea let us give you some common mobile phones battery capacity. Please note Cellphones come with lithium-ion type of batteries.
|Charging Power |
|Samsung Galaxy Note 20 Ultra||4,500mAh||25W|
|iPhone 12 Pro Max||3,687mAh||20W|
In general you should get a solar power bank that is at twice the capacity of your phones battery , however the more capacity of power banks lets you charge your phone multiple times at one go. n general you should get a solar power bank that is at twice the capacity of your phones battery , however the more capacity of power banks lets you charge your phone multiple times at one go.
Another downside to a Solar power bank is that it will not have a fast charging feature but you will be secure in having charge to carry around. However as the solar panels are only as a backup and this is just an additional feature. A 10w Solar panel can take up to 40 hours to fully charge a 10000mAh power bank. And if you are looking at 5 hours of sunlight per day that’s around a week to fully charge that’s around 5 – 6 days.
Features of a Good Portable Solar Charger
Foldable and Portable
A foldable solar panels that encloses neatly with Velcro tape to ensure ensure everything keeps together and can be easily carried or placed in a backpack.
This allows you to put your phone or power bank to avoid it heating up in direct sunlight.
USB ports and output
Charger can come with either a Micro USB, Type C or USB Ports. Depending on the type of phone you use it is important to check the ports. These ports also have different outputs and may not be fast charging ports.
Hooks or Metal Eyes for Hanging
Preferably metal eyes that cannot be torn over time. This will ensure you can hang the solar charger where there is sufficient light.
Waterproof and Dust Proof
A waterproof Solar Charger that will not spoil when exposed to the elements of the outdoors.
A MPPT Charge Controller ensures that it doesn’t overcharge the device. Some have a dc to dc converter but avoid ones with just a voltage regulator because it just throws away power.
A Smart IC chip automatically detects the device connected to ensure the proper charge is delivered.
Price Per Watt
An efficient solar panel ensures you get your money’s worth.
1. Big Blue 28 Watt Solar Charger
As mentioned before we picked the Big Blue as our top pick for more reasons that just the ammeter. If you love the outdoors and camping this solar charger can be a great companion. The Big Blue Solar Charger is comprised of four foldable 7 watt solar panels, two usb ports and is a light weight coming in just slightly over a pound. A built in digital ammeter comes in handy as it allows you to track the charge from the solar panels.
- High Efficiency with a consistent conversion rate of between (21.5%-23.5%)
- Made up of four foldable solar panels that make it easier to move around with
- 28 watt Solar panels that can provide enough power to charge most.
- 2 usb ports with fast charging capabilities.
- Smart Intelligent Charging (Can detect the device plugged in)
- Industrial strength PET polymer that is both waterproof and dustproof.
- It has hooks to hook on trees or backpacks when charging.
- Comes with a nifty storage bag
- Pouch not insulated and its black so it tends to heat up. Not good when you storing phone or powerbank. Best is to place your phone or bank in the shade.
- Does not work with IPAD pro
2. Nekteck 21 Watt Solar Charger
The Nekteck solar charger is a great choice for someone who is going for backpacking. It is light weight, portable and foldable and allows for easy placement on a backpack. It is made up of 3 high efficiency monocrystalline solar panels with upto 20% conversion.
It has a mesh cool design that allows you to place your phone or power bank in the shade side. This is a great feature to have as it prevents your device from heating up from direct sunlight.
It has two ports (3.0 A and 2.0 A) and can fast charge two devices at the same time on these two ports without overheating.
It is compatible with all iPhone, Tablets and USB supported devices.
- Foldable and Portable
- High efficiency
- Fast Charging
- Rugged Canvas for the outdoors
- Charge rate changes with Sunlight intensity
3. FEELE Solar Charger Power Bank
The Feele Solar Charger has rugged design that is shock proof and dust proof with a black protective cover at the bottom.
The foldable solar panels with 2.1 A USB ports and a 24,0000 mAh power bank.
The powerbank can be charged by solar or via usb and can charge most phones.
Since it has a power bank the main distinguisher from the others is that it can be used at night. It has a flash light that can be used as a night light.
For charging you can easily strap on a tree, kayak or backpack.
2 connectors (USB and Micro USB)
24000MaH Power bank
Can charge iPhone 6s 10 times, iPhone 7 9 times, Samsung S7 5 TIMES
Dual 2 A ports allows you to charge two devices simultaneous
Perfect for the outdoors
It is not fast charging
4. Yelomin 20000mAh Solar Power Bank
Portable Small, compact, and lightweight.
Nice silicon case protects from rain, dirt and shock and offers firm.
2 LED flashlights with moderate brightness.
Solar charging (only as backup make sure to fully charge with USB before leaving for the outdoors)
Takes a long time to charge with solar power.
Doesn’t have a Fast Charging Feature