Want to Buy a Solar Power Bank?
Free and Perpetual Electricity is Possible!
Unless you live under a rock somewhere (like a certain lovable pink starfish), you would certainly have heard of a power bank. Those chargeable electronic devices that many smartphone users today simply cannot live without.
Now then, what is a solar power bank?
Conceptually, a solar power bank has the capability to use light energy to charge the battery cell inside the power bank. The light energy from the sun is collected by a solar panel which is mounted on one side of the power bank and then converted into electrical energy which is then used for charging purposes.
There are a few benefits to utilising this variant of a standard power bank.
Firstly, sunlight equals zero-cost charging source. Free electricity!
Secondly, you will not need to find an electrical outlet to charge your power bank (great for long hikes, camping trips, anything to do with the outdoors, etc).
And lastly, your own impact on the environment will likely be reduced as you are not relying on electricity potentially generated by fossil fuels. In the current global march towards a net zero carbon world, this is an oft-overlooked benefit.
Given that sustainability has become such key concept in today’s world (think sustainable agriculture, sustainable fashion, etc), it is rather surprising that solar power banks have fallen below the radar of most people.
I would like to bring it back onto the radar.
If you have not considered purchasing a solar power bank or am unsure about whether to purchase one, this article should provide you sufficient information to make a considered decision.
What Should I Look Out For When Buying One?
1. Number of Solar Panels
The number of solar panels that your power bank has is key to the speed of charging.
More panels = more sunlight collected = faster charging.
It is as simple as that.
Some brands come with as many as five panels. If you are fussed about a need to charge up your power bank quickly, my advice is to get as many panels as you can find attached to your power bank.
2. Quality of Solar Cells
Go for the quality brands. Quality brands sell power banks with solar panels that have a higher efficiency and a lower degradation profile.
This means smaller panels (improved portability) and longer lifespan.
There are many quality brands in the market including, but not limited to, RAVPower, GoerTek and BLAVOR which you can consider for your next purchase.
3. Battery Capacity / Charging Times
Naturally, the larger the battery capacity, the longer it will take to charge.
With a single panel, it will take close to 50 hours for very large batteries (>25,000 mAh). This time estimate varies significantly based on weather conditions and product specifications. More panels (as mentioned earlier) will improve charging times significantly and you should see closer to 20–30 hours for a full charge for very large batteries.
For regular-sized batteries (say 10,000 mAh), you should expect between 5–10 hours for a full charge.
To decide the best battery capacity for your own usage, I have presented a table below that shows you the amount of battery capacity (in mAh) that you will require for specific devices.
How About Prices?
The great thing about solar power banks is that you can have all the benefits (including being eco-friendly) at a very affordable price.
No requirement to sell an arm and a leg to purchase one.
A quick check on Amazon will show you prices ranging between USD 30–40 for most brands and specifications.
How to Optimise the Performance of my New Solar Power Bank
Now that you have bought a new solar power bank, it is also important to maintain it and look at optimising its performance.
To understand how to optimise performance, I have listed below key factors that affect the performance of your solar power bank.
Degradation
One general fact that people do not know about solar panels — similar to the battery cells in the power bank, the solar panels degrade over time. This means that their ability to convert sunlight into electrical energy (technical term: performance ratio) declines as time passes.
This degradation generally results from humidity, temperature changes and UV damage.
Now, how much degradation actually happens?
The greatest degradation happens on Day 1. This is also known as “light induced degradation” and you can expect degradation of between 1–3% in the first year, depending on the quality of the panels you use.
In subsequent years, annual degradation will be around the region of 0.5–1%.
This means that after a period of 10 years, the performance of your solar panel will be around 90% of its original performance levels.
Does this mean that your power bank will take longer and longer to charge up? Not necessarily. As mentioned, the battery cells in your power bank degrade over time too.
Thus, if the solar panels degrade faster than the battery cells, then yes, it will take longer and longer to charge up your power bank.
To get the best performance, it is necessary to obtain the best quality solar panels (more on that further below).
Angle of Sunlight
While the panels will collect solar radiation from the sun, from sky and even from reflected sunlight off the ground, the angle at which the sunlight hits the solar panel surface will affect the collection efficiency (getting more technical here).
For maximum efficiency, the sun rays will need to hit the panel at a 90 degrees angle (ie. perpendicular to the panel surface).
That said, realistically, you will not be holding your power bank and angling the panel at the perfect angle to the sun at all times.
During long hikes or camping trips, it could be worth thinking further about how to position your power bank on top of your backpack or around your resting area to optimise your charging times.
Intensity of Sunlight
Before I jump into this factor, it would be wise to quickly explain how a solar panel actually works.
Simply put, a solar panel collects photons (you can think of them as light particles) and uses it to knock electrons off atoms, thus generating a flow of electricity.
Therefore, when more intense sunlight is available, there will be more photons collected/harvested, resulting in more electricity generated. In certain countries or certain weather conditions (eg. cloudy), the sunlight can be relatively dispersed (ie. less intense) and you may notice that charging times will increase.
While not practical for most settings, theoretically, if you are faced with weak sunlight conditions, you could take a bunch of curved mirrors and focus light rays onto the solar panels, thus increasing the amount of photons that can be collected by the panel.
While I have described a few key factors above, there are a few other factors such as shading (from clouds, shadows) and soiling (from dirt and dust on the panels) that does affect the performance of the solar power bank.
Keep these factors in mind and you will be able to obtain the best possible performance from your new solar power bank.
Solar Power Banks and Decarbonisation
I am confident that solar power banks have a part to play in a zero carbon future.
If everyone was to participate and live sustainably in an eco-friendly manner, it is my belief that we will very quickly achieve our decarbonisation goals and slow down, or even reverse, the effects of climate change and adverse ecological impact.
The choice is yours.
