Solar power bank: Best Power Bank Portable Charger 2022

Solar Power Bank: What is a Power Bank?

A  Solar Power Bank is a portable solar mobile charger that can store Solar Energy with integrated solar cell  and supply power from its built-in battery through a USB port. Power Banks are popular for charging USB charged small electrical devices like Smart Phones, Tab, Handy Cams, Emergency light, Smart Watch etc.  Power banks use lithium-ion batteries, for stored charge itself.

Best waterproof solar power bank

Best waterproof solar power bank is a special version of portable solar rechargeable power bank with integrated solar cell, mostly used for solar phone charger and other handy small devices. It can charge itself in cloudy condition. They are mainly used for long outdoor tours and traveling, where you have no nearby outlet to charge your mobile or any other small handy electrical devices battery.

Solar power bank how it works

Solar power bank how it works. A portable solar power bank can have a battery capacity of only 10000 mAh, enough to charge your device two to three times. A large solar power bank offers an energy capacity of 50,000 to 100,000 mAh. This is enough to charge tablets, your Smartphone or your notebook several times.

solar power bank how to use

solar power bank how long to charge

10 best solar power bank buy online

The great guide to the Solar Power Bank

Generally, solar chargers are common in places where there is no power supply. Apart from that, they are also popular with people who enjoy long trips, camping, hiking and other outdoor activities.

The compact design, ease of use and portability are the reasons why these small energy storage devices are being used more and more frequently.

The technology behind the idea

But what is behind the technology? Can we leave our power adapters at home soon and load our smart phones with the help of the solar power banks?

The idea seems very appealing at a glance, but it has to contend with a blatant problem: The area is extremely limited by the size of the power bank.

Since the solar panel is mounted on the back of the external battery, the size is very limited. Common power banks have a surface of about 15 x 8 cm, which corresponds to 120 square centimeters. Even the smallest solar chargers have a surface of about ten times that.

The small surface of a solar power bank is not enough to produce a significant amount of electricity. If a small solar charger reaches a current of 1.5 amps under ideal conditions, the external battery can produce a maximum of one tenth of it due to its size.

With 150 mA you can count in the absolute ideal case. To make matters worse, the production of power banks due to the built-in battery cells is already relatively expensive anyway and the additional solar module continues to feed on the profits of the manufacturers.

Therefore, especially in so-called. Solar Power Bank often fined solar panel with a low efficiency.

Fortunately, the problem was also recognized by some manufacturers in the industry: Renowned manufacturers that were on the market last year with Solar Powerbanks have stopped their production lines as they could not provide the customer with added value.

Three situations in which a solar power bank can be useful

Despite the well-founded criticism of the model Solar Power Bank, there are a few applications in which the devices can be useful. Batteries lying around unused for a long time lose their charge. So it may happen that when the battery is really needed no performance is available. But if it is a battery with built-in solar panel, this can provide for a charge retention. Provided, of course, that the device can lie in the sun. Due to the continuous current flow, the battery can always be kept at full charge and is always fully operational.

is it worth buying a power bank with solar cells?

Devices that you can charge through a power bank include:

Are you looking for a charger + battery storage that draws its energy directly from sunlight? Then you are right here. The article explains exactly what to look for when buying, which power bank for your ideas is the right one and which devices are recommended.

When traveling or during power outages, a power bank is definitely the right choice. They are thus more independent and always have an energy backup in their pocket. With enough sun you do not even need to give up your electronic devices in the wild.

Dimensions, weight and workmanship

The powerbank is made of rubberized plastic and looks very robust. The corners are reinforced with an additional impact protection, the sides are grooved and therefore particularly grippy. The power bank has a hinged metal eyelet, there is the possibility of the power bank, for example. attach to the equipment with a small carabiner. The outlets and entrances are well protected against moisture and spiky water with protective caps. The solar cells are a bit lower and are also well protected against scratches and damage. All in all, the power bank is not completely waterproof but definitely very robust, outdoor-capable and processed excellently.

The RAVPower Solar Charger 25000mAh does not fit in a trouser or jacket pocket due to its dimensions and the weight of more than half a kilo and should therefore fit its place e.g. to find in a backpack.

The charge status is indicated by 4 blue LEDs. In addition, the bright white LED on the front side can be activated by a long press of the ON / OFF button, which due to its brightness can definitely be called a flashlight.


The manufacturer indicates the capacity of the internal lithium-ion batteries with 25000mAh or 92.5 watt-hours. Due to the voltage conversion basically occur losses, which are dependent on the height of the output current. We measured the following capacities:

The highest capacity is achieved at 2A (typical charging current of modern smartphones) and is still over 90% of the internal capacity which is a very good value.

With this capacity, e.g. Charge the battery of the iPhone X (10.3 watt hours) over 6 x fully.

Even the Apple iPad Pro 12.9 “(36.71 watt-hours) can be fully charged twice.

(for these examples, a 20% loss on loading was expected)

Outputs, powers and voltages

The RAVPower Solar Charger 25000mAh has four sockets, two of which have outputs as USB-A, one micro-USB input and one input / output as USB-C socket.

One of the two USB-A outputs is designed as Qualcomm QuickCharge 3.0. QuickCharge 3.0 compatible with up to 12 volts can also be quickly charged via the Mico-USB input.

All three outputs can be used in parallel with the iSmart and the USB-C output sharing the maximum output current (3.0A according to the manufacturer, 3.4A in our test). Two devices can be charged in parallel to USB-C and iSmart (USB-A), but may not charge at the maximum possible charging speed. By contrast, the USB-A QC 3.0 output is independent of the other two outputs in terms of its performance.

All in all, the RAVPower Solar Charger 25000mAh delivers up to 6.8 amps (test result) or a power of up to 33.5 watts (test result). The manufacturer’s specifications are exceeded.

The output voltage of the iSmart USB-A output is highest, and even at a load of 3A is still well above 5 volts. Due to the high and stable output voltage even under load, the fastest possible charging of the connected devices is to be expected. Many devices reduce the maximum power consumption when the voltage drops too much under load. The high voltage is therefore very positive.

The power bank switches off automatically when it falls below a minimum charging current. The automatic switch-off prevents permanently connected devices from being repeatedly recharged and therefore permanently damaged. For very small consumers (e.g., fitness trackers, GPS watches) with low power consumption during charging, the problem arises that the automatic shutdown completely or partially prevents charging. The minimum output current of the RAVPower Solar Charger 25000mAh is pleasingly low with only 40mA for such a large power bank. As a rule, there are hardly any problems when loading fitness trackers and GPS watches. However, the charge may not quite reach 100 percent for very small devices because it comes to automatic shutdown when the power consumption drops below 40mA.

Recharge powerbank

At some point even the largest power bank is empty and has to be reloaded. The RAVPower Solar Charger 25000mAh can be charged via Mirco-USB or USB-C. It’s even possible to load in parallel via USB-C A and Micro-USB (QC), dramatically reducing the load time. We measured the following charging

Capacities and times:

This short charging time in the parallel use of both inputs is pleasing, even if this type of charge in practice is probably rather rarely representable. But also over QuickCharge the power bank is at least clearly under 8 hours again fully operationally ready. Somewhat disappointing is the charging power via USB-C which is well below QuickCharge and does not reach the theoretically possible 15 watts even in the top.

Charging via solar

One of the key features of the RAVPower Solar Charger 25000mAh is its built-in solar module. The manufacturer indicates a power of 5V at 300mA so 1.5 watts. The full charge of the power bank should be possible in 85 hours (at full sun). The solar cell has an area of ​​approx. 90 cm2. Based on the manufacturer’s information that would be an efficiency of 16.6 percent for the solar cells, which is quite realistic. However, it is now the case that the charging current of the solar cells first has to be converted into a charging voltage for the battery. A lithium-ion battery is not 100 percent effective, meaning the energy you need to spend to charge the battery is higher than the energy that the battery has to give back. In addition, the energy delivered by the battery must then be converted back into the output voltage.

We tested the solar performance by completely discharging the power bank and then recharging it via the solar cells. The irradiation was measured constantly via a solar logger. With an irradiation of 1000 W per m2, the RAVPower Solar Charger 25000mAh achieves an output capacity of 0.7 watt-hours per hour. The efficiency corresponds to about 7.8 percent. Although this is only the 1/2 of the efficiency specified by the manufacturer, however, a loss of 50 percent by the whole conversion steps and the intermediate storage in the battery is quite to be expected. For the small area 0.7 watts are still a very good performance. Comparable products that we had already tested in the past (see solar charger in the comparison test) brought it to the same area only 0.5 watts.

The manufacturer specifies 85 hours for a full charge, which we consider realistic. However, it should not be forgotten that this time is only reached when the power bank is also exposed through the full 1000 W per m2 which is achieved here in Central Europe only at lunchtime and in really clear skies and perfect alignment. If you put the powerbank into the sun somehow and do not re-align every 10 minutes, the recharge time can double quickly. But even the 85 hours require in midsummer loose 10 days of full sunshine. So there should be no false expectations of the solar charging power.

Since you can reach quite 5 watt-hours on a sunny day, even if the power bank is not always perfectly aligned, the charging power is still enough to keep a smartphone permanently in standby or to use it for a few minutes a day. Seen in this way, the power bank enables a self-sufficient power supply for a smartphone under optimal conditions.

When assessing the solar charging options, it really depends on the consideration. Short time to the sun and then a smartphone completely load, something is completely unrealistic given the small area! In case of an emergency, having an option to charge your smartphone for a short time at the end of a sunny day and then use it for a short while, the product is well suited for that.

In addition, you can of course store the power bank in a sunny spot and thus prevent the self-discharge and for a long period of time (months rather than weeks) also fully recharge.

How do I use a power bank correctly?

There are many myths about batteries and their correct use. Many of them are rumors or simply obsolete. New batteries, as they are also installed in the current power banks are either lithium-ion or lithium-polymer batteries. While older batteries, such as nickel-cadmium batteries still had a memory effect, ie the loss of capacity that occurs when you had recharged the battery in half full state, there is no longer with new batteries. On the contrary: “It is advised not to completely discharge batteries, but to carry out partial charges again and again, which can even increase the life of the energy storage device.” says outdoor equipment expert Boris Gnielka.

If you do not need the power bank for a long time you should not store the battery fully charged. It is best to store the power bank in a cool and dry place, half charged. For example, in a plastic bag in the basement. Ideal are temperatures between 15 and 18 degrees Celsius. This too can extend the life of the battery cells. However, the cells discharge themselves over time, which is why you should recharge it after a while to avoid a complete discharge. Low temperatures, heat and overcharging will damage lithium-ion or lithium-polymer batteries.

Which power bank is best for outdoor use?

Who wants to buy a power bank to take them on tour, should pay attention to very specific features. For example, the device should be IP67 certified. This standard states that the housing is both dust-proof and that it withstands temporary submersion in water, up to a maximum depth of one meter and a maximum of 30 minutes.

Furthermore, the impact resistance is an important criterion. If the power bank falls down, then the battery cells must not be damaged. Otherwise it can come to a short circuit and in the worst case, the power bank catches fire. Special outdoor power banks have therefore very robust housing in which the battery cells are stored safely. The vibration must not matter to modern batteries.

Powerbank Accessories: What should be there?

Most power banks are initially shipped with a standard USB charger. Better devices have their own power adapter that makes charging the batteries faster than using the USB port. Also a manual should be there. Ideally, the energy storage also include other adapters for notebooks, notepads and tablets, etc. included. If you buy outdoor power banks, they are often supplied with more accessories, such as attachment straps, carabiners or an integrated compass.

What additional features should a power bank bring?

One of the most important features that a power bank should have is a switchable charging voltage. If you not only want to charge your smartphone via the external battery, but also supply other devices that are not satisfied with 5 volts charging voltage, additional adjustment options are useful. Modern power banks also have an intelligent charging mode. The charging protocol of the connected device is recognized via a microchip and the charging is optimally adapted to protect the batteries.

Outdoor power banks are often additionally equipped with useful gadgets such as flashlights, solar cells or UV lamps. However, the full equipment is also reflected in the weight. So many models weigh more than 500 grams. For trekking tours these outdoor power banks are then less suitable.

If you are looking for the egg-laying Wollmilchsau, you can also buy outdoor power banks, which have an integrated Bluetooth speaker. Outside campsites or beaches you will use these devices but less.

How big should the capacity of a power bank be?

The rule of thumb for power banks is that the higher the capacity of the battery, the higher the weight. So if you need an extra charge for your GPS device on a multi-day trekking tour, for the possibly a smaller power bank to 5,000 mAh (milliampere hours) is enough. These weigh on average by 100 grams. Those who do not put off the extra weight or do not feel it directly on the bike or canoe tour can also fall back on more powerful outdoor power banks. Power banks with a capacity of 10,000 mAh weigh on average between 200 and 250 grams. Models with more than 20,000 mAh capacity can weigh over half a kilo.

But the larger outdoor power banks have two or more USB ports. So when you’re in the team, you can share the batteries and save the weight of additional outdoor power banks in the group. “It’s better to take bigger power banks because the ratio of weight to performance

How does a solar power bank work?

A solar power bank is a device that converts solar energy into electricity, stores it in a battery, and then, when needed, supplies that power to other devices. The stored solar power can be used for a variety of electrical devices – directly, or to charge their batteries.

Benefits of the power bank

  1. Charging a solar power bank uses photovoltaic – so free solar energy. There are different types of power banks in the market. Some are only additional batteries, which are charged from the mains. But we are talking about solar powered devices. Unlike other energy storage devices, these devices can use environmentally friendly energy – the sun!
  2. The devices are absolutely environmentally friendly. The production of solar cells and batteries consumes today due to the mass production even small amounts of energy, which bring back the devices in the course of their useful life in any case.
  3. The device can be used everywhere. On hikes, you can attach the power bank partly to the backpack and charge the power bank during the tour. Relaxing on the beach or in the open air is not a problem anyway.

You can charge any Micro USB-enabled device.

  1. Compactness: These chargers are compact and no burden in terms of weight or size. They are perfect for long trips, camping trips, hikes and especially for outings in remote areas.
  2. Economic Benefits: In many cases, the items we buy are liabilities. For example, a power bank without solar cells has to be constantly charged from the mains. Here are additional costs. This is not the case with a solar power bank. The used solar energy is reliable and above all free of charge.
  3. Backup Charging System for Prepper: In case of power failure, disasters or if you are in a remote area, you have a small emergency power supply with these bones. You charge your electrical appliances even if there is no energy.
  4. What types of solar chargers are there?

There are many manufacturers of solar chargers with different concepts and designs. As a result, there are different models and types on the market. The most popular types:

  1. Small, portable models that can charge a variety of small devices, including cell phones, cell phones, iPods, and other small portable devices.
  2. The fold-out models. These could e.g. can also be placed on the dashboard of your own vehicle and, depending on the type, can be plugged into the cigarette lighter socket to charge the vehicle battery when it is not in use.
  3. Is the solar power bank expensive?

The price depends on its battery capacity, solar panel technology and the brand

Price ranges for power banks with capacities between 10,000 mAh and 20,000 mAh should be between 20 and 30 €. More than 20,000 prices depend more on the quality. With really large capacities like 50,000 or 100,000 mAh it will be harder to find combinations that have the solar cells integrated. However, you also get devices that separate the power bank and the solar panel. Here are some examples of current prices:

Best Guide to Buying a Power bank

As with the purchase of other products, the comparison of course makes sense. Always look closely at the features of each model and choose the one that suits you best. But which features are most important? We now come to this:

Are my devices compatible with the power bank?

A powerbank is compatible with most smartphones and electronic devices. Typically, the chargers have one or more USB ports that allow you to connect each of your devices with a USB cable.

The ability to charge an electronic device or not depends on the type of USB port. Often the power bank has a universal USB output, but some have Micro USB or Type C charging ports. If your device does not have the right connection, you can use an appropriate adapter.

In general, however, most phones are directly compatible with the power bank because of the universal USB port. Therefore, you can charge smart phones with a power bank.

Competitable mobile devices that should use power bank.

What capacity does the solar power bank have?

Perhaps the most important factor of any additional mobile battery is the capacity of the lithium battery.

The battery capacity indicates the amount of energy that can be stored in the backup battery and is generally expressed in mAh (milliampere hours).

However, if you need a backup battery that will last for days while you’re on a camping trip or hiking off the mains, or if you need to power multiple or larger units, you’ll need a larger solar power bank with capacities of between 20,000 and 50,000 mAh, depending on the number the day.

Also keep in mind that a large capacity requires more and more time to fully charge.

How long does it take for a power bank to be charged in the sun?

One way to estimate this is to apply the following formula:

Charging time = (capacity of the power bank) / (power of the solar module)

If we are dealing with a solar energy bank of almost 25,000 mAh and have a fold-out 5-W panel, then:

(25,000 mAh * 5V) / (5W * 0,8) = 100Wh / 4Wh = 25 hours

5V refers to the voltage at which the battery is charged.

0.8 is a factor that refers to the losses of solar energy in electrical conversion.

If you have access to a power outlet, use it. You could shorten the load times by 5-6 hours.

Fully charge your solar energy bank before each trip by plugging it into a power outlet and use solar energy as a constant charging source while you are outdoors.

Thus, some factors affect the charging speed when sunlight is the only source of energy.

  • The performance of the solar cells
  • The battery capacity
  • The sunshine

The battery conversion rate. Unfortunately, after the powerbank has been charged to over 50%, this value decreases.

On the basis of recommendations of the manufacturers, the descriptions often give an approximate indication of how long it takes to charge only with the sun.

Number of USB

Battery capacity.

The next point should help with the calculation.

How often can I charge my smartphone with a full power bank?

Each smartphone has a lithium-ion battery. To find out how many times you can charge your device with a full power bank, follow these steps:

First check the battery capacity of the smart phone in mAh.

Then divide the battery capacity of the power bank, when fully charged, by the power needed by the smartphone.

The result is the number of charges available to the device.


Battery of the Iphone 7 = 1960 mAh; Powerbank with 10,000 Ah

10,000 / 1960 = 5.1 charges

A 25000mAh Solar Powerbank is powerful enough to charge an iPhone X / 8 more than 10 times, an iPhone 6s up to 11 times, a Galaxy S8 9 times, an S7 up to 6 times, or an iPad Mini more than 3 times.

Consider the type of ports the smartphone needs and check that the USB power bank has them. If not, just buy an additional adapter.

Another fact that you might consider, which is not restrictive but worth knowing, is the levels of current that your phone needs to charge. The normal USB outputs have a 2A output, but may also have a 2.1A, 2.4A, or even 3A output. This affects the charging speed of the cell phones, but it can also affect the performance of the battery because mobile phones come with one specific rated current are designed.

Check the battery specifications of your smartphone to see if the requested rated current is lower or higher than the Powerbank USB port. If it is lower, the Power Bank will easily output only the power needed by the phone. However, if it is higher, you should look for a different energy bank.

Portable Facility

When considering multiple options, consider which powerbank is foldable, whether there is a steel loop to hang it on the backpack while walking (it is important to take the time to charge the battery while walking), and generally what dimensions the device has (also unfolded).

Another important fact that needs to be considered in mobility is related to shelf life. Since the charger is likely to be used outdoors, it is very important that the battery and the solar panel have a protective cover against water, dust and shock

Specification of the solar cells

The main reason for choosing a solar battery charger is that it charges the battery with the energy of the sun, without depending on the network performance.

Since the main power source here is the solar module, it is important to check the quality of the solar cells. The more efficient the cells, the more energy they can produce, even with the same area.

Useful features

  1. These additional options may include:
  2. LED displays
  3. LED illumination
  4. flashlight
  5. aesthetic design
  6. Quick Charge 3.0 USB ports

Supplied accessories such as a USB cable or an adapter


Check how the specifications of your devices and the power bank you want to use with solar energy explain.

Power banks have become a useful tool, especially when on vacation or traveling, as modern smart phones need to be recharged more frequently. The introduction of solar charging cells in power banks has relieved travelers and adventurers, because they no longer have to worry about power outages.

Mobile devices are great because they connect us to the outside world and help create memories that last forever. This is only possible if your devices are properly charged while on the move.

Our readers are advised to read the reviews and specifications of the Power Bank before purchasing. With the right device you will enjoy the mobile freedom even more!

Generally, solar chargers are common in places where there is no power supply. Apart from that, they are also popular with people who enjoy long trips, camping, hiking and other outdoor activities.

The compact design, ease of use and portability are the reasons why these small energy storage devices are being used more and more frequently.

Devices that you can charge through a power bank include:

This power bank is charged by the sun while charging a smartphone and a tablet or other device. 10,000 mAh solar charger – For tablet and smartphone – Robust design, waterproof and easy to carry, fits in most cases – Double-sided solar panel that charges from any light source, even from the inside or outside – Also includes built-in flash and On / Off button for on-demand charging only – Use direct sunlight for best results – Will continue to collect and store energy even when the device is off – Saved energy can be used for up to 2 weeks – Waterproof appearance – Fully compatible With smartphones, tablets, GPS , Car Cameras, All USB Models, 5V Outputs, Protected for All Electronic Devices and Gadgets Like Music Players, MP3 Players, Lamps, and More Dual USB 2.1 / 1.1 Amp Port for Charging 2 Devices Simultaneously – Resistant to ABS- Plastic Enclosure – Supplied with a USB micro cable for charging via a UBS connector


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