All mobile devices such as Mobile Phones, Gaming Devices, Digital cameras etc, have a limited amount of battery, which eventually run out and need to be recharged.
You might know how frustrating it is when your mobile device is about to run out of battery and you have no way of charging it.
A power bank solves this issue as you can recharge your mobile device on the go when you do not have access to a power outlet.
But, what if your power bank is out of battery too? Can you charge a power bank with a solar panel? You can charge most standard power banks using solar panels. The ability to charge a power bank with a solar panel depends on how much power the solar panel can output which is determined by its power rating. There are different types of solar panels that come in different shapes, and sizes as well as power ratings. So, you will need to select a solar panel that is capable of supplying the voltage and current required to charge a standard power bank.
Other factors that can affect charging the power bank with a solar panel are the amount of sunlight, angle of sunlight, surface area etc.
A deeper look at a solar panel and power bank
Taking an in-depth look at solar panels, and power banks will give you a better understanding on what type of solar panels can charge a power bank.
A note to be made is that, you get power banks that come embedded with a solar panel on them. These power banks have been tested with that particular solar panel to ensure that it can be charged efficiently.
Our concern is whether you can use a standalone solar panel to charge a standalone power bank.
The Solar Panel
A solar panel has the ability to convert sunlight into electricity. It does this using a process known as the photovoltaic effect.
It is a great choice for powering homes, businesses, etc, as it is a form of clean renewable energy.
Solar panels come in a variety of ratings, shapes, and sizes.
The ratings of the solar panel are of great importance when creating a solar power system (which is a combination of a solar panel, charging module, and battery).
Solar panels have three ratings that need to be known which include ; Power, Voltage, and Current.
These ratings are the maximum ratings that the solar panel is capable of generating. However, the solar panels ability to deliver these maximum ratings depends on the intensity of sunlight.
Due to this, it is not effective to power electronics directly using a solar panel, as the power levels are not constant and vary with varying intensities of light.
Instead, a solar panel is used to charge a rechargeable battery source which can then be used to power electronic devices. A charging module is used between the solar panel and battery to regulate the incoming power from the solar panel to make sure a constant voltage and current is delivered to the battery.
The Power Bank
Our mobile devices all have a limited amount of power which eventually runs out. This can be an issue if you are travelling and have no way charging your device.
A power bank was created as a solution to that problem. It essentially is a portable charger that can charge your mobile devices when there is no other means of charging them.
Like the solar panel, a power bank comes in a variety of shapes, sizes, current capacities, and ratings.
The main specifications to look for when purchasing a power bank is its Output Voltage, Input Voltage, Output Current, and Capacity.
Output Voltage – This is the maximum voltage a power bank can output (you will need to match output voltage of your power bank to the input voltage of your mobile device)
Input Voltage – This is the input voltage required to charge the power bank.
Output Current – The maximum amount of current the power bank is capable of delivering
Capacity – This is the maximum amount of charge the power bank can store when fully charged. The more charge that the power bank is capable of storing, the more times you will be able to charge your mobile devices.
The conventional way of charging a power bank is to use a wall charger (which you use to charge your mobile device) via its input port.
Selecting a solar panel to charge a power bank
There might be times where you might have forgotten to charge your power bank before heading out on your long journey (or you might be on a journey where there isn’t any electricity available).
So, now your mobile device and power bank have no charge!
To avoid this situation from recurring again in the future, you have the option of using a solar panel in conjunction with the power bank to effectively create your own mobile solar power system.
As you saw above, a solar panel by itself cannot power electronics as its output power varies and requires a battery to store all that energy.
A power bank can be used as that battery source and store the charge generated by the solar panel. The good thing is that the power bank has an internal charging module that can regulate power levels delivered to its battery via the solar panel.
Most mobile electronic devices (like smartphones), operate at 5 volts. Therefore, you will need a power bank that has an output voltage of 5 volts.
Due to this, a solar panel with a voltage rating of 5 volts will need to be chosen as well.
A solar panel that is say 3.7 volts, will not have capability of charging a 5 volt power bank. So, the output voltage rating of a solar panel needs to match the input voltage rating of a power bank.
What solar power rating is required to charge a power bank?
How effective a solar panel is when it comes to charging a power bank comes down to its power rating.
The maximum power rating (P) of a device is the product of its maximum voltage and maximum current (P = V x I). Its unit is watts.
An example would give you a better understanding. Below is a table of values of current and voltage for a solar panel and power bank (values are chosen randomly for this example).
| Solar Panel (output values) | Power Bank (input values) | |
| Voltage (V) | 5 | 5 |
| Current (I) | 0.5 | 2 |
| Power (V x I) | 2.5 | 10 |
The solar panel can charge the power bank, as it matches it in voltage values. However, it does not do it very effectively as it only delivers 2.5 watts of power, and the power rating of the power bank is 10 watts.
So, to be more effective, a solar panel with a higher output power rating will need to be selected for the power bank in this example.
Since the voltage of the solar panel needs to be 5 volts, its current will need to increase from 0.5 A to 2A in order to match the power banks power rating.
Why not just charge a mobile device directly with a solar panel?
A mobile device needs a constant voltage and current to be charged effectively. Wall chargers can provide them with this constant power that will charge them at constant rate.
While it is not impossible to charge a mobile device directly with a solar panel, it isn’t very practical. This is because the solar panel will not be able to provide constant power all the time.
So, a better option is to store the energy generated by the solar panel in a battery source which can then get delivered to a mobile device at a constant rate.
What else is needed to charge a power bank with a solar panel?
To connect the solar panel to the power bank, you will need the right type of cable which fits the input port of a power bank.
There are many different types of input ports, but the most common of them being Micro-USB. This however, is slowly being replaced by Type-C ports.
So, you will need to check what kind of port your power bank has, and accordingly wire the solar panel with a cable that matches that port.
Do you need a charging module? No, you will not need a charging module as the power bank already has its own charging module.
How long will it take to charge a power bank with a solar panel?
A power bank’s capacity is the maximum amount of charge it can store. The larger the capacity of a power bank the more charge it will be able to store, and vice versa.
The unit for a power bank’s capacity is given in mAh (milli-amp-hours).
To calculate how long it will take to charge a power bank to its maximum capacity, you will need to know its maH value, and the amount of current being supplied by the charger.
So the time it will take = mAh / current.
For example if we have a power bank with a capacity of 1000 mAh, and a current of 1A is provided by the charger, it is going to take 1 hour (we need to use Amps values, so 1000mAh = 1Ah. We then divide 1Ah/1A to get 1 hour)
But, since we are using a solar panel to charge the power bank, another factor that will determine how long it will take to charge it, is how constant the level of current is being delivered by the solar panel.
The amount of current being delivered depends on the output current rating of the solar panel and the amount of sunlight that the solar panel is exposed to. The more sunlight, the greater the power output.
So, the solar panel will need to be exposed to constant intensity of sunlight in order for the power bank to be charged at a known rate.
Other factors that will affect how long a power bank will take to charge using a solar panel
So, how long a power bank will take to charge using a solar panel depends on two variables; the capacity of the battery, as well as the amount of sunlight the solar panel is exposed to.
But, there are other factors that come in to play as well:
- Placement of the solar panel – as well all know the sun does not stay stationary during the day. So, the placement of a solar panel to catch the most sunlight should be taken into consideration
- Whether the solar panel is stationary or not – You might be doing a hike and need to charge the power bank daily. You could place the solar panel on your backpack as you walk. However, this might not effectively capture the most amount of solar energy as you could be changing direction constantly.
- Weather – Obviously the weather is a major factor. You won’t get the most out of the solar panel if the sun is not present on cloudy days.
Where can you charge a power bank with a solar panel?
Charging a power bank with a solar panel requires one thing, sunlight.
Below are some great places:
- In your car
- Outside your home
- Inside you home
- Backpack as you walk
- Pretty much wherever you can find sunlight =D
Advantages of charging a power bank with a solar panel?
One of the greatest advantages of charging a power bank using a solar panel is that it is great for our planet. Since we are generating electricity using the sun, it does not harm the environment in any way and is one of the most used ways of generating renewable energy.
Another great selling point is that it is free! You will be saving on your electricity bills when you start charging your power bank with a solar panel.
Also, since the sun shines on pretty much all parts of the earth (that I know of), you can charge your power bank, and therefore your mobile devices with a solar panel, no matter where you are!
Disadvantages of charging a power bank with a solar panel?
All things that come with advantages, will have its disadvantages, unfortunately
Here are some of the disadvantages of using a solar panel to charge your power bank:
- Only effective when sun at its brightest
- Cannot charge at night
- Weather dependent
- Charging times vary depending on factors like angle of sunlight, intensity of sunlight and weather.
How can you charge a power bank faster using a solar panel?
If you notice that it is taken a long time to charge your power bank with a solar panel, even when the sun is at its brightest, you have three options:
- Add another solar panel with the same rating in parallel. This will double the current output. Adding a third solar panel in parallel will triple the current output, and so on.
- Upgrade your solar panel to one which can deliver more current.
- Get a bigger solar panel (one with greater surface area)
