If you have ever bought or used a solar power bank then you know about the frustration of getting a phone fully charged using these small solar panels. First of all, most of these solar power banks’ solar panels 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.
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 pack. In most types, the solar panel is quite small, and solar charging is only a backup option. You must charge the bank via an AC source.
What Size for a Portable Power Bank
Before you decide on the power bank or solar power bank for your phone or laptop, you first consider the battery capacity of your device. If you want to have an idea let us give you some common mobile phones battery capacities.
| Phone | Battery Capacity (mAh) | Charging Power (Watts) |
| Samsung Galaxy Note 20 Ultra | 4,500mAh | 25W |
| iPhone 12 Pro Max | 3,687mAh | 20W |
| OnePlus 8T | 4,500mAh | 65W |
| Samsung S9 | 3000mAh | 18W |
| iPhone 8 | 1821mAh | 20W |
In general, you should get a solar power bank that is twice the capacity of your phone’s battery, however, the more capacity of power banks lets you charge your phone multiple times in one go. n general you should get a solar power bank that is twice the capacity of your phone’s battery, however, a more capacity power bank lets you charge your phone multiple times at one go.
A 10,000mAh power bank can charge the Galaxy Note 20 ultra twice and three times for the iPhone 12 Pro Max. You can go as high as 20,000 mAh and this will charge the same phones 4 times over and 6 times over.
FEELE Solar Charger Power Bank
The Feele Solar Charger Power Bank has a rugged design that is shockproof and dustproof with a black protective cover at the bottom. The foldable solar panels come with 2.1 A USB ports and a 24,0000 mAh power bank. The power bank can be charged by solar or via USB and can charge most phones.
For charging you can easily strap on a tree, kayak, or backpack.
Features
2 connectors (USB and Micro USB)
24000MaH Power bank
Can charge iPhone 6s 10 times, iPhone 7 9 times, Samsung S7 5 TIMES
Water Proof
A dual 2 A port allows you to charge two devices simultaneously
LED light
Perfect for the outdoors
Cons
It is not fast charging
The downside to a Solar power bank is that it will not have a fast charging feature but you will be secure in having a charge to carry around. However, the solar panels are only a backup and this is just an additional feature.
A 10w Solar panel can take up to 40 hours to fully charge a 20,000mAh 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.
Picking a Solar Charger for Your Phone
As stated before solar charger has a solar panel alongside the battery pack. This is the main differentiator between a solar power bank and a regular power bank. The wattage of the panels is indicated and this can guide you in choosing the best use such as heavy-duty or light, mobile, and either a single outlet or multiple outlets. A phone needs 3watts to 5 watts 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 won’t fully charge your cellphone on cloudy days. Solar chargers are tested at STC (Standard Test Conditions) at a humidity of around 1.5 and an ambient temperature 25 degrees Celsius and are flashed with 100 watts 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 for 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 Watt 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 phone’s 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.
What to Look for When Buying a Portable Solar Charger
Foldable and Portable
A foldable solar panel that is enclosed neatly with Velcro tape to ensure everything keeps together and can be easily carried or placed in a backpack.
Storage Pockets
This allows you to put your phone or power bank on to avoid it heating up in direct sunlight.
USB ports and output
The 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.
Charge Controller
An 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.
Intelligent charging
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.
Big Blue 28-Watt Solar Charger
As mentioned before we picked the Big Blue as our top pick for more reasons than 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, and two USB ports and is lightweight 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.
Our top pick is the Big Blue 20W Solar Charger. It is 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 plugging 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:
Pros
- 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
Cons
- The pouch is not insulated and its black so it tends to heat up. Not good when you store a phone or power bank. The best is to place your phone or bank in the shade.
- Does not work with IPAD pro
Portable Power Station
Portable power stations are a great alternative to a power bank. They’re portable, rechargeable, and can be used to charge your phone up to 21 times. Portable power stations are in fact a more powerful power bank.
A portable power station is basically a portable battery pack with a higher capacity than your average power bank. They can be charged from an AC outlet, from Solar Panels, or from a 12v port in your car.
You may think that you’d never need such a big battery pack, but the reality is that we all do. Portable power stations are great for usage at camp or at home, when power outages occur, this practical model will take you off of the grid.
A 500Wh portable power station is equal to a 50,000mAh power bank. This means you can charge your phone 20 times over. A 500Wh power station can output of 8-12 W over more than 24 hours. That means it can power a small 40W TV for 5 hours, a 5-Watt LED light for 40 hours, and It can also power a small camping fridge.
Another advantage of a Portable Power Station is that you can easily recharge it by plugging it into the 12V DC Carport, using a solar panel, or using the 110 V AC power charging cable at home.
Its LCD display provides input wattage, output wattage, and current battery charge level. It has two 5 V DC (USB), 12 V DC and 110 V AC outputs.
Can You Build your own power bank?
So can you build your own power bank? Yes you can. It’s not that hard to do, but it’s also not easy. And there are some safety issues and potential hazards involved. There are various types of batteries you can use including old phone batteries, and 18650 lithium-ion batteries that you can get from Adafruit or other sources.
LiFePO4 Cells are also popular with power packs and are recommended when used with solar panels. But I recommend buying from a known manufacturer who will warranty their products. This is important because if the cells leak or short out or become damaged in any way through your own fault (or even through no fault of your own), then you have no recourse for replacement or repair except by contacting the manufacturer directly — and that could take weeks or months depending on their policies.
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