Best Solar Power Bank- Complete Buying Guide

Gadgets by FileEdge on March 23, 2020 Solar Power Bank 2.49K views

For most of the outdoor enthusiasts, the solar power bank is an essential gadget. It is an excellent option for charging your cell phones, cameras, and other gadgets. With the help of it, you can charge your devices even when there is no availability of power source. These ones are very convenient and portable as well. These chargers that come with one panel have a compact design. But these recharge themselves slowly using the Sun’s energy. Chargers that come with multiple panels increase the charging speed.

How Does Solar Power Bank Work?

Solar energy is an Eco-friendly way to generate electricity. The solar power bank is equipped with a small built-in panel that helps to charge a rechargeable battery. The panel is usually a photovoltaic cell. Here, phosphorus replaces the silicon and then creates a negative charge. And, boron replaces silicon to the other end that creates a positive charge. It helps to create an electrical field.

Due to the electric field, electrons can move around easily within the cells. When sunlight (a stream of photons) hit the panels, the photons strike the free electrons. And then, these knock it out of the circuit. Then, a conductive plate collects the electrons to create electricity and recharge the battery.

Most people prefer to choose Lithium based batteries. It is because Lithium has a high tendency to lose electrons. It indicates that electrons can move from one terminal of the battery to another terminal easily. These ones are ideal for charging your phone.

Benefits of Using a Solar Powered Battery Charger

The solar powered battery charger helps to store energy. And it allows the user to use the energy when it is a cloudy day. It is the primary benefit of this charger. You can even charge your cell phone battery without taking them out in the Sun.

The essential benefit of solar powered battery is that these ones don’t need external electrical sources to recharge your batteries. As there is no need for using an electrical source, you can get a few subtler benefits. The solar cells create no emissions, waste or byproducts. The photons pass through the silicon. And here, the electricity comes from the transfer of energy from photon to an electron. During the process, it frees the electron and allows it to flow. Electricity is an energy carrier, not a form of energy. You can generate electricity through the photoelectric effect.

What are the Types of Solar Energy Chargers?

You can get three types of chargers that are available in the market:

Simple 1 or 2 stage controls
PWM (pulse width modulated)
Maximum power point tracking (MPPT)

Simple 1 or 2 Controls: It comes with shunt transistors. These ones help to control the voltage in one or two steps. Its function is to short the solar panel while a certain voltage will arrive.

PWM (Pulse Width Modulated): It is a traditional type charger. Anthrax, Blue Sky, etc. are some examples of it.

Maximum power point tracking (MPPT): MPPT solar charge controller is very famous in today’s market. These ones can identify the perfect working voltage and amperage of the solar panel exhibit easily. The output you can get from this one will be more than 10-30% compared to a PWM controller.

Solar Power Bank Buying Guide

Multiple factors are there that you need to consider before buying the best solar power bank. Here, we have given a few tips that can help you to choose the right one as per your needs.

Battery Capacity
Solar Panel Specs
Portability
Charging Ports
Battery Type

Battery Capacity

You need to determine the battery capacity first. The battery stores energy. It is measured in mAh (Ampere-Hour) or Wh (Watt-Hour) units. It lets you know about the amount of power that the battery can put out at a certain duration.

Usually, we want to know how much charge our device is draining. How much we can charge a full battery depends upon the mAh number on the power bank. That’s why you should determine for which purpose you will use the solar power bank.

Solar Panel Specs

Usually, these banks can be charged with a standard power outlet. You don’t need to rely upon the power grid entirely. It allows you to store power using the Sun. While you’re going to determine the quality of the solar panels, you need to examine both the panel cells. Besides, you also need to test the panel size. The larger panel will collect more energy from the Sun. You need to look for the specs also of all solar panels that you are purchasing. And then, you need to find out the power output. Sometimes, you may need to pay a little bit extra for achieving the highest efficiency. Besides, you also need to consider the size of the solar power bank you are charging via these panels.

System Portability

As soon as you decide for which purpose you will use it, you need to consider its portability. You should buy lightweight ones that you can carry anywhere. In case you want a power source for a camper-van, then try to buy those things that you can move around. A few higher-capacity power banks are available that are slightly larger than a car battery.

Usually, panels are fold-able. And a few banks are there that come with panels built onto the battery.

Charging Ports

When it comes to the battery capacity and portability, the number of charging ports required depends upon you. A few users want to charge multiple phones or tablets at the moment. In this case, you can look for those banks that have multiple USB ports. The larger ones have numerous plug-in options ranging from USB, standard outlet prongs, to additional option. If you are looking for backup at home in emergency times, then try these ones. Families who are searching for an off-grid car camping solution can also use it.

Battery Type

Lithium-ion polymer power bank batteries are mostly available in the market. However, many variations are there, such as lead-acid or saltwater batteries. And plenty of factors are also there to consider before deciding the appreciate battery type. You need to know the depth of discharge and the entire lifespan of the battery.

The depth of discharge means the full storage capacity of the battery. Actually, it indicates the battery’s state of charge.

On the other hand, the Lead-acid batteries are traditional off-grid solar solutions. These ones have a shorter lifespan compared to the other battery types. Usually, these have a lower depth of discharge. Most people prefer to use lead-acid batteries while converting the entire household energy system to solar. And these are budget-friendly also.

Again, the Saltwater batteries are a homemade DIY solar solution. It is a perfect Eco-friendly option as the battery depends on saltwater electrolytes. There is no heavy metal. But the drawback is that there is no information available regarding its longevity.

Lithium-Ion Polymer batteries are the prevalent battery available in the market. These ones have a longer lifespan and a higher depth of discharge compared to other battery types.

How can I speed up my solar power bank?

Here, we have given you five easy ways to speed up the solar bank.

Charge outdoors

If you place it in a hotter place, then the charging speed will get slower. It is the most important thing that you need to know at first. The high temperature usually decreases the efficiency of solar cells. Therefore, if you want to increase the charging speed, you have to charge it outdoors. And the place should be well ventilated. When the solar panels are inside the backpacks, these can offer faster performance. And it will work a bit faster when you take these out from the backpacks.

Open windows if charging outdoors are not possible

While you are charging a solar power device, the efficiency reduces from 20% to 50%. Windows don’t allow the cells to get activated. Even, these can stop the activation state for some time. But it happens when the windows contain UV protection. That’s why it is better for you to open the windows while charging.

Make sure that solar cells are facing towards the Sun

Most of the time, we keep the solar panels flat on the table. And we think that it will work properly. But it is not going to happen. It can get merely half-power compared with tilting the panel towards the Sun. That’s why always make sure that you placed the solar panels facing towards the Sun. However, the charging speed can be reduced a little bit. It is because the inclination of the Sun in relation to your device changes constantly.

Every solar panel doesn’t have a similar efficiency

All panels are not similar although these look the same. You can choose the Crystalline panels that can charge two times faster than the thin-film panels. However, both come in the same size. Usually, the rigid ones are quicker and more durable than the flexible ones. Therefore, you need a flexible one that is 2× larger than the rigid panels. Thus, the same amount of power can be gotten.

Try to use shorter cables

If you’re using a shorter cable to connect the panel and your device, then it doesn’t increase the charging speed. However, always try to use a long cable for the panel so that it can reach full sunshine.

Solar Power Bank vs. Solar Charger

Here, we have given a perfect comparison between these two. The first one has portable chargers and internal batteries. The batteries store electrical energy and then power your phone. But it weighs lighter than the solar chargers. On the contrary, these chargers use solar panels and turn solar power into electricity to power your device.

Pricing

The price range of these portable chargers are from $30 to $250. However, it depends on the brands, the amount of energy in watts, and the charging capabilities. A few high-end chargers can provide power up to 200 watts. And these ones can charge car batteries. You can carry the banks from one place to another. You can choose the expensive ones also if you require large ones. But those who have a lower-end price range can offer approx 7-14 watts of power. A few chargers are there that need more than six hours of direct sunlight for charging your device completely. But it depends upon the exact watts number and the brands.

If you want to charge your device only, then you don’t need an expensive power bank. Portable ones are convenient in this case. The price range of these portable ones is from $20-$125. Hence, the price depends upon the brand and energy storage capacity.

Sizing

The size of chargers differs according to the brands.

Weight

If you want to buy lightweight ones, then you can choose lower-watt chargers. These are lighter than a pound. However, you can use a RAVPower 24 watt charger that weighs 1.65 pounds. A few models are available that have a larger capacity. These ones can weigh up to 13-14 ounces.

List of Top 9 Best Solar Power Bank

Blavor Power Bank
QiSa Power Bank
Riapow Wireless Solar Portable Charger
Addtop Solar Power Bank
Yelomin Solar Power Bank
Nekteck Solar Charger
OUTXE W20 Wireless Power Bank
Feeke Charger
Hiluckey Charger

Best Solar Power Bank– Buying Guide

Here, we have given the top nine best solar power banks. Let’s have a look at these.

Blavor Solar Power Bank

Description:

We have given this power bank the top position in our list of the top best solar power banks because of its highest maximum output rating of 18 watts. It can charge your phone very quickly. This inbuilt wireless charger of the product offers a decent output rating of 10 watts.

The battery capacity of the charger is 10000 mAh that is lower compared to other models. It comes with dual USB ports, USB Type C input, flashlight, compass, and even a wireless charger. The manufacturers offer a 1-year warranty on the product.

Features:

Qi Wireless & Solar Power：

It is not only a 10,000mAh wireless power bank but also a wireless charger. This charger supports iPhone XR/ XR MAX/ XS/ X/ 8/ 8plus, Samsung Galaxy S9 or S9 Plus, S8 or S8 Plus and other mobile devices.

Reminder：

The Blavor has a small panel size, large capacity and uncontrollable sunlight intensity into consideration. But the one thing you need to remember is that you have to charge it completely before you use it.

Extensive Tested Charging Times:

Blavor solar power bank can charge itself in 6hours using a 5V/2A adapter. The product can even charge iphone7 plus 2.2times, iPhone X up 2.3times, iphone8 up 3.5times.

Durable and Compact Size：

The charger consists of premium ABS materials and a lithium polymer battery. It is both sturdy and durable. The charger comes with two USB, type C, dual flashlights and a compass kit. It weighs very light.

Dual Flashlight & Compass Kit：

It contains a bright dual flashlight and a portable compass kit. It is ideal for outdoor activities such as camping, cycling, fishing, travelling, hiking and beaches.

Pros:

High charging speed
Wireless charger
USB Type C is available

Cons:

Requires a lot of time for charging itself.

QiSa Solar Power Bank

Description:

We have given QiSa powerbank second rank on our list. The reason is the charger have the highest capacity rating. It comes with a maximum output rating of 15.5 watts. What makes it special is that the item has a battery capacity of 35800 mAh.

It enables you to use the dual USB output ports and the wireless charger. The QiSa charger comes with a 6-month warranty.

Awesome Features:

Fast charging:

The maximum Micro USB Input is DC 5V 2A whereas the USB Output is DC 5V 3.1A. It shows the maximum wireless output of 5V 2A. The material of the product is ABS+TPU. QiSa has a flashlight of 2.6W(210 lumens). And the power conversion rate is 70.5% or more than that.

Multi-Functional LED Lights:

It comes with a powerful light LED flashlight that makes it an ideal outdoor companion. The charger has a lights-Low light-Flash-SOS.

Waterproof:

You can use in wet environments or rainy days. But you should not pour water on it.

Upgrade Qi Wireless Charging:

QiSa allows 10W fast wireless charging. It is a Qi portable charger. The product supports iPhone 11/XR/ XR MAX/ XS/ X/ 8/ 8plus, Samsung Galaxy S10/S9/S9 Plus S8/S8 Plus and all qi-enabled devices. The charger is completely cable-free and tangle-free.

High-Speed 3 Outputs:

It can support up to three electronic devices to charge simultaneously. Qisa offers two fast output ports and one wireless output charging for your device, tablet or other electronic devices. USB-C Port & Micro USB Port are the two inputs available here.

Two times fast charge:

It has an upgraded built-in smart chip. This charger allows you to charge two times faster than others. It is far more stable compared to other products. This charger converts Fluctuation voltage to Stable voltage. Qisa is able to stabilize the equipment.

Pros:

Dual USB ports and a wireless charging
Fastest charging

Cons:

Shorter warranty period compared to others.

Riapow Wireless Solar Portable Charger

Description:

If you are searching for any portable charger, then it can be the right choice for you. We can say that it is a value for money product. The charger has a maximum output of 15.5 watts charging speed. It is only available over its USB ports as the charger has a lower output rating.

The charger contains four output ports that are high compared to others. What makes it very convenient is its 26800 mAh battery capacity. The Riapow wireless solar portable charger is very reliable to the people. The charger has a 1.5-year warranty.

Awesome Features:

Advanced Wireless Portable Charger:

Riapow wireless solar portable charger is a cable-free power bank with wireless output. The portable charger is compatible with QI-enabled phones for inductive charging. It supports iPhone 11 Pro Max / XS Max / 8 plus, Samsung Galaxy S20 / S10 / Note 10 Plus, and so on.

Ultra-High Capacity:

The 26800mAh battery capacity makes the product handy. The size of Riapow charger is similar to the usual phones. It can charge iPhone 11 8 times, Galaxy S10 6 times and iPad mini three times. This charger can last up to eight days on a single recharge.

Fast Charging:

The charger has the ability to charge four devices simultaneously at full speed. It can detect your device automatically. The maximum charging speed is 3A. It can charge iPhone 11 completely within 1.3 hours.

2.5X Recharging:

With the USB C charger, you can charge this product within seven hours. It is 2.5 times faster than 1A input. These have USB C ports also that helps to charge your device.

Outdoor Essentials:

Riapow wireless solar portable charger is equipped with solar panels that are helpful in emergency times. You can charge your device via sunlight. It is equipped with LED flashlight along with “Steady-Flashing-SOS” 3 modes. This product is very durable, and it has a highly sturdy design.

Multi-Functional LED Lights:

It comes with a powerful LED flashlight. The Strong-SOS-Flash mode of this product helps the user to guide through darkness and ass well as in an emergency.

Waterproof and Dustproof:

You can use the battery pack in an outdoor wet environment. The product is splashproof, dustproof and shockproof.

Pros:

Different output ports
In-built LED flashlight
Offers high performance

Cons:

Slow charging speed

Addtop Solar Power Bank

Description:

One of the best things about this product is you need not spend too much on this product yet you can get decent capacity and performance from it. Addtop comes with a charging speed of 10.5 watts. But it doesn’t provide a wireless charging option.

The battery capacity of the product is rated at 25000 mAh. The product comes with dual output ports that help to charge your device quickly. It has a warranty of one year.

Awesome Features:

25000mAh charger:

Addtop Power Bank comes with a huge battery backup that makes it perfect for outdoor usage. It can charge iPhone 6 around ten times, Samsung S6 around seven times and iPad Air around three times.

Four fold-able panels:

The charger is portable and it comes in a handy size. When you fold the power bank, it will look slightly larger than folded iPhone X. Addtoop Power Bank can absorb solar energy more than any usual charger.

Fast charging:

The dual USB output ports of the product allow to charge two devices up to 5V/2.1 with Quick Charge. Moreover, it can stop automatically when the device is charged fully. The charger assists to avoid over-heating & over-charging situations.

LED lights:

The emergency LED lights of this charger are very bright. Therefore, these help to guide you in darkness. You can carry it to any outdoor trip or any emergency events. The charger is very easy to carry. You can use it for traveling, hiking, and camping. It comes with a Micro-USB cable and a user manual.

Pros:

High charging speed
Excellent battery capacity
Dual output ports

Cons:

Wireless charging capability is unavailable.

Yelomin Solar Power Bank

Description

If you are looking for an affordable power bank, then Yelomin is an excellent option for you. The product has a maximum output rating of 10 watts. The output of the charger works for both 2A and 1A charging devices. Its battery capacity is 20000 mAh. Yelomin Solar Power Bank comes with dual USB ports, inbuilt LED light, and a compass. These make the product a great camping companion. But the product has merely a 90-day long warranty.

Awesome Features:

High-Quality Portable:

It consists of durable and reliable ABS+PC+Silicone material. Yelomin contains a Solar phone charger, compass and two bright LED flashlights. You can carry this product if you are going for any camping, hiking.

Works as a reminder:

The charging speed of the product depends on the intensity of sunlight, solar panel size, and panel conversion rate. That’s why it may take a long time to charge. The USB is the fundamental way to charge the battery bank. You can use the USB cable of this product for charging this charger only. But, you must not use it to charge other devices as it can slow down the charging efficiency due to incompatibility.

Compatible with Multiple Devices:

The product supports different Smartphones, tablets and other USB devices. It has more than 900+ recharge life-cycles. The charger comes with a Flashlight or a Carabiner. It is very durable and reliable.

Convenient Smart Express Charge:

Yelomin charger comes with dual USB and powerful LED light. With the help of it, you can charge two smartphones simultaneously or a tablet at full speed. It has two led lights that allow you to use flashlights using the Steady-SOS-Strobe mode. Besides, the Five pilot indicators of the charger indicate the status of the battery charger. The green light turns on while charging by a solar, blue light on when USB charging. The Yelomin has an external battery charger that helps to recharge by any outlet.

Pros:

Reasonable price
Decent performance
Comes with a flashlight as well as a compass

Cons:

Don’t have a long warranty period.

Nekteck Solar Charger

Description:

Are you looking for the best charger at a low-cost? Nekteck is a good option in this case. It comes with a large 10,000 mAh battery capacity. The product comes with two USB ports for charging devices continuously. Multiple one-panel chargers are there that take a long time to get fully charged. Besides, it is equipped with an efficient solar panel that helps to recharge very fast. It has a bright LED flashlight, side grips, and an anti-slip design. Nekteck Solar charger is both shockproof and rain-resistant. You can carry this product when you are going camping or hiking.

You can connect it to your phone directly for charging. The energy of the three High-efficiency panels makes Nekteck Solar charger effective. You can unfold it. And then, its 21-watt panel. This charger also has dual USB charging ports. They permits two devices for charging at once at a maximum output current of 3 Amps total. It doesn’t matter how long you are going to make your trip – you can use Nekteck Charger whenever you need. It is best for backpacking.

Awesome Features:

High Efficiency:

It is equipped with 21 watts High-efficiency Sun-power panel. It can charge two devices at the same time. You can use this product for emergency purposes.

Fast charging Technology:

Nekteck Solar charger comes with an in-built- smart IC chip. The maximum charging speed of the product is up to 2.0A each port or 3.0 A max overall.

SmartIC Technology:

It comes with a new SmartIC Technology that has its own microchip. It detects those devices plugged into through USB PIN signals. These can give you output at full power and full charging speed.

Highly Portable:

Is weighs very light 18 oz. The dimensions of the product are 6.3x 11.1x 1.06 inches when folded or 26.3x 11.1 inches when opened. That means you can carry this product easily.

Highly Durable:

Due to constructed with superior material, this product becomes durable enough and suitable for outdoor use. Due to constructed with superior material, the exterior part of the charger won’t get damaged easily.

Package Content: The charger comes with a 21W Solar Charging Panel, 80cm Micro USB Cable, User Manual, and a 12 Month Warranty period.

Pros:

Includes user manual and 80 cm Micro USB Cable
12 Month Warranty
Durable and portable

Cons:

Poor charging speed

OUTXE W20 Wireless Power Bank

Description:

It comes with a military-grade construction that makes the charger very durable. OUTXE W20 Wireless Power Bank is an ideal companion for hikers, kayakers, anglers, and other outdoor enthusiasts. It comes with an IP67 waterproof rating. It means that you can keep it in three feet of water for up to 30 minutes. The product is also dustproof as well as shockproof.

OUTXE W20 Wireless Power Bank is equipped with a powerful 20,000 mAh battery. The high battery capacity allows the charger to charge an iPhone XS up to seven times and a Samsung Galaxy S10 up to five times. The product has one more specialty that is you can charge it without wire. It has two extra charge ports— type C and micro USB cords. It enables you to charge up to three devices at a time. The charger can charge itself using the 2W high-efficiency panel under sunlight. It is perfect for emergency purpose usages.It is a best solar power bank for camping.

Awesome Features:

Long-lasting:

The OUTXE W20 Wireless Power Bank charger is designed in such a way so that it can last for a long time. The product is IP67 Waterproof, dust proof, shockproof, and non-slip. The reinforced rubber cap and military-grade construction protect the product from any kind of damage.

Truly Wireless Charger:

Now, you don’t need to use tangled cords. Just invest money in buying USB-C / lightning cables. It has 1 USB QC3.0 output,1 USB output 2.4A, and one wireless charging pad. These help to charge your phone without wires.

50% Faster charge:

The Type C and Micro USB offers the fastest overnight charge time. It usually takes 6.5 hours for a complete charge.

Pros:

Quick charging
Allows to charge without wires
Long-lasting

Cons:

Rubber covers are unable to prevent water.

Feeke Charger

Description:

If you want to buy a charger of high capacity, then it is a fantastic option. The charger can offer you a high maximum output rating of 15 watts. Feeke Charger can charge your devices quickly when you combine it with the wireless charging pad.

It comes with a high capacity rating of 32800 mAh. The dual input and the triple output ports of the charger allow you to enjoy a high battery capacity. It also offers an IP66 water resistance rating. The product comes with a 1-year long warranty. It is a best solar power bank for backpacking.

Awesome Features:

Large-Capacity:

The battery capacity of Feeke Charger is 32800mAh. The battery of this much high capacity allows you to charge multiple devices simultaneously. It is portable enough. Therefore, you can keep your mobile fully charged anytime and anywhere.

Powerful LED flashlight:

The built-in LED flashlight is very strong. And therefore, it can last for a long time with ease. The charger comes with three working modes. You need to double click your power button to switch into a strong light, flash, SOS. These can send the users emergency signals.

Qi wireless charging:

Feeke Charger comes with a great Qi wireless charging technology. This portable charger supports all Qi-enabled devices. It has in-built dual USB outputs that allow you to charge three devices at the same time.

Dual input ports:

It has dual input ports— high-speed Type-C and Micro USB. These ports help to charge devices at the same time. You can get the maximum possible charging speed. The charging speed of the product is almost 2× compared to ordinary ones that come with a single input port.

Heavy-duty IP66:

Feeke Charger is dust proof, shockproof, and waterproof as well. It consists of ABS material that makes the product durable. The charger comes with a certified IP 66 rating.

Multi-Protection:

The high battery capacity helps to keep your phone away from overcharging, over-current, over-voltage, and short circuits.

Pros:

Waterproof
Quick charging speed
Inbuilt LED

Cons:

Charges through the cable only.

Hiluckey Charger

Description

The maximum output rating of Hiluckey Charger is 15 watts. It comes with dual flashlights. Hiluckey is a best solar power bank for camping.

It has a battery capacity of 26800 mAh. The charger provides four output ports like a wireless charging one, and so on. The manufacturers offer 1.5-year-long warranty on the product.

Awesome Features:

Gigantic Capacity:

By using this charger, you can charge your mobile about ten to twelve times. If you have a tablet, then you can charge it 4-5 times for an average of nine days of usage per charge.

Fast Charging:

Using Hiluckey Charger, you can charge 4 devices at the moment. It can charge a 3000mAh phone within 1.5 hrs or a 6000mAh laptop within 2.5 hrs.

D&QC Tech:

It comes with a blue USB port and USB C port. These allow you to work with a 12V laptop. You can use a PD or QC adapter also to charge it properly. With the help of a USB-C port, the charger can charge your phone very fast.

Outdoor Use:

The charger has an in-built LED flashlight that comes with an SOS mode. You can use it as an emergency light. This product is both waterproof and dustproof. As a result, it is perfect for outdoor usages.

Pros:

Includes user manual, and user cable
Twelve-month warranty
Wireless charging
Multiple ports are available.

Cons:

A little bit expensive

Conclusion:

When you are traveling on long road trips, camping trips, trekking trips, you can find your power bank losing all charge. And that’s why you must have a high capacity power bank. You can choose any of these solar power bank as well. But before buying, you should definitely check the buying guide.

Frequently Asked Question

What are the best solar chargers?

The name of the best solar chargers are as follows:

BigBlue 28W
Hiluckey
BEARTWO
Nekteck 21W
Anker 21W

Do solar chargers really work?

Solar chargers can charge your cell phone in emergency times. But these usually take a long time and work only in bright sunlight. The working function of a solar charger depends on your usages, and type of the phone battery.

What is the best solar power bank?

Multiple different solar power banks are there that are best for different needs.

QiSa Solar Power Bank( best overall)
Nekteck Solar Charger( best for the budget)
OUTXE W20 Wireless( perfect as a waterproof)
Goal Zero Nomad 5( single panel)
FEELLE Solar Power Bank( fold-out)

Are solar powered power banks any good?

These solar powered power banks can recharge themselves completely using sunlight. If you are going for a vacation, then with these solar power banks, you can charge your device easily. Only a few hours of charging this bank can be enough for one-day usage.

What should I look for in a solar power bank?

When you choose a solar power bank, the surface area is the one that you need to consider. If the solar panels have larger sizes, then they can collect more sunlight. Therefore, it can store more energy.