Using Solar Panel to charge Power Bank

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Professor1991

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Hello All,

I'm somewhat getting on the eco bandwagon and an idea that's caught my interest is solar power. On a recent trip, due to constant phone usage, my friends found themselves soon out of phone charge (I didn't as my phone has a 10'000mah battery :cool:). Although we had a power bank, it was fairly small and suffice it to say, they also needed charging ! I've been thinking of getting a large capacity power bank but I was wondering is it possible to charge it using just fairly inexpensive solar panels ? I know it would take ages to charge (relative to the capacity of the power bank) but I would like to know if in theory, can it work.
Many Thanks
 
In theory it is possible but would depend on the size & quality of your solar panels, as well as the weather. Charge time could be anywhere from days to weeks so more an issue of practicality than anything else.
 
Professor1991 said:
Hello All,

I've been thinking of getting a large capacity power bank but I was wondering is it possible to charge it using just fairly inexpensive solar panels ? I know it would take ages to charge (relative to the capacity of the power bank) but I would like to know if in theory, can it work.
Many Thanks
Click to expand...


It is indeed. I have one. There are easy to buy and relatively cheap (think £50) - just charge your power bank during the day (mine normally gives a fully chartered power bank over a day in Southern Europe) then charge devices from power bank at night

I found this may help http://www.independent.co.uk/extras...rgers-for-phones-iphone-camping-a6981856.html
 
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I expect a lot depends on where you intend to use it. Southern Europe will much sunnier than the Northern Isles generally so you may get away with a smaller panel to pack ratio. If you want to use a panel under our grey skies it should be a bigger better quality one.
 
I was thinking of the possibility of using a fairly cheap panel off eBay and just sticking it at my window at home and allowing that to charge a power bank slowly. Or I could just mount a panel to the sunroof of a car and just let it charge ?
 
There's one I've eyed up on amazon.... very well reviewed. Haven't tried it yet tho. It's this Anker power port solar 21w:

http://amzn.to/2r2sWJ7

My use would be while travelling and at home, pop it on charge to fill up a power bank or two. Haven't worked out how long it would take to break even, cost is decent at £49 but UK sunshine/cloud cover is irregular even this time of the year so it could take longer than I realise. But hey, geeky fun :)
 
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Most interesting. I find this to be a fairly enticing prospect of good, "free" energy. I emphasised the free as well, the panels aren't cheap but I like to think, I'll get even.
I found this particular model which states you can direct charge to a power bank.
http://www.mobilesolarchargers.co.uk/shop/details/msc-15w-portable-solar-panel-charger
Most articles I've seen regarding solar panels seem to only mention them charging more heavier types of battery as opposed to something more mainstream like a power bank.
I intend to explore this option coupled with a quality power bank (Ideally over 20'000mah), I'll be enjoying a trip !
 
Have you done a calculation of how much energy that will give you over the course of a year, and how much that same energy would cost from your electricity provider?
I have a feeling that it will take many years to recoup the cost (nut may be wide of the mark....). And you also then have the fact that the item is not that green, in that it has to be manufactured, transported a number of journeys, packaged and disposed of at the end of its life. I also believe that solar cells contain toxic heavy metals such as cadmium. Personally, from an eco perspective i would be happier using the electricity from the mains which i think will have significant economies of scale that may make it significantly greener.

EDIT, its been a long time since i studied physics, but hopefully somebody can vaildate this calculation
my phone has a battery of 1,570 mAh and 3.8W.
In round numbers 1.5*3.8 = 5.7 Wh.
A kWh costs around 12p. For that 12p i could recharge my phone 1000 / 5.7 = 175 times
or a cost per charge of 12 p / 175 = 0.07 pence per charge.
That assumes 100% efficiency, if i guess around 70% efficiency, that cost conveniently becomes around 0.1 pence per charge.
If you go for a cheap eBay solar charger that was linked above at £7.49, and you used it daily, it would take 20 years to recoup the cost. (£7.49 / 0.1p) / 365
If you go for an expensive charger that was in the Independent article linked above at £449, and you used it daily, it would take 1230 (!?) years to recoup the cost. (£449 / 0.1p)/365
 
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a 10,000 battery? Wow. What is it? Evn the high end phones are packing about 4000
 
Lynton said:
a 10,000 battery? Wow. What is it? Evn the high end phones are packing about 4000
Click to expand...

It's essentially an extended battery. The company is called Zerolemon and it's for a Samsung Galaxy Note 3. I just take out the original 3'xxx battery and put this in. Granted this battery makes the phone look like a power bank/ brick but the phone lasts a good while ! The battery is a tri cell so it's effectively 3x the standard batteries. Although it takes a while to charge (I charge it when I'm asleep), I routinely get 15 hours + of screen on time whereas the current standard is between 3 - 5.
 
Rapscallion said:
EDIT, its been a long time since i studied physics, but hopefully somebody can vaildate this calculation
my phone has a battery of 1,570 mAh and 3.8W.
In round numbers 1.5*3.8 = 5.7 Wh.
A kWh costs around 12p. For that 12p i could recharge my phone 1000 / 5.7 = 175 times
or a cost per charge of 12 p / 175 = 0.07 pence per charge.
That assumes 100% efficiency, if i guess around 70% efficiency, that cost conveniently becomes around 0.1 pence per charge.
If you go for a cheap eBay solar charger that was linked above at £7.49, and you used it daily, it would take 20 years to recoup the cost. (£7.49 / 0.1p) / 365
If you go for an expensive charger that was in the Independent article linked above at £449, and you used it daily, it would take 1230 (!?) years to recoup the cost. (£449 / 0.1p)/365
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I love this sort of thing!

In the first line you meant 3.8V, not 3.8W. But that's just cosmetic. All the numbers are correct.

I guess it just goes to show that one doesn't use these solar chargers to save money.
 
Well doesn't that maths just throw my experiment out the window !

I still nonetheless want to go ahead and try this. I've managed to acquire a power bank with a advertised capacity of 26'000mah. Would a 5V solar panel be sufficient as it's input is rated as 5V. Also if a solar panel is rated as 15V (or higher), would that mean it'll charge the power bank quickly ? (seems obvious I know but I'm a noob on this subject).

Also is a solar panel with just a USB output sufficient and at what point do you start to include a power inverter, etc.... ?
Thanks
 
Professor1991 said:
Well doesn't that maths just throw my experiment out the window !

I still nonetheless want to go ahead and try this. I've managed to acquire a power bank with a advertised capacity of 26'000mah. Would a 5V solar panel be sufficient as it's input is rated as 5V. Also if a solar panel is rated as 15V (or higher), would that mean it'll charge the power bank quickly ? (seems obvious I know but I'm a noob on this subject).

Also is a solar panel with just a USB output sufficient and at what point do you start to include a power inverter, etc.... ?
Thanks
Click to expand...

If the solar panel has a 5v output, that will mean you just need a male USB A (normal USB) to a male micro USB plug to connect the solar panel to the power bank. If the power bank is an eBay job there's a fair chance that t won't actually have a 26000 MaH capacity but will still take a while to charge from flat with the solar panel.
 
Professor1991 said:
I still nonetheless want to go ahead and try this. I've managed to acquire a power bank with a advertised capacity of 26'000mah. Would a 5V solar panel be sufficient as it's input is rated as 5V. Also if a solar panel is rated as 15V (or higher), would that mean it'll charge the power bank quickly ? (seems obvious I know but I'm a noob on this subject).
Click to expand...
Not enough information provided. The basic relationships you don't seem to have taken into account are:
* power = voltage x current (eg 1mW = 1V x 1mA)
* energy = power x time (eg 1kWh = 1kW x 1h)

Firstly, how many Volts is the power bank rated at? Its energy storage capacity is a number of mWh, which you get by multiplying the 26,000mAh by the voltage. So for example my phone battery is 2550mAh, but it runs at 3.85V, so the energy storage is 2550 x 3.85 = 9817mWh = 9.8Wh.

Secondly, how many Watts are the solar panels rated at? The 5V or 15V you mentioned are the output voltages, but you need to know what power they generate, measured in Watts. The solar panels on my roof are rated at about 250W per square metre, so that should hopefully help you work out whether you have the decimal point in roughly the right place. (Though I expect a portable panel won't be anywhere near as powerful.)

So then if you know the energy storage capacity of the power bank in Watt-hours, and you know the power output of the panel in Watts, divide the storage capacity by the panel output to work out how many hours it will take to charge the power bank.
 
One other thing to take account of is the relationship between the theoretical output of the solar panels and the actual output, which is caused by (a) the varying angle of the sun, and (b) clouds.

For example, here's a graphic of the output from the panels on our roof on a very sunny day recently. We had wall-to-wall sunshine that day. But although the panels are rated at 4kW, and we had over 15 hours of sunshine, you can see that we didnt get anywhere near 4kW at any time that day and we didn't get anywhere near 60kWh for the day as a whole. The power output only exceeded 3kW for about 3 hours, and the total was only 28kWh. This is because of the angle of the sun; it varies relative to the panels throughout the day, and even at its highest it's not quite optimal at that time of year.
Screenshot_20170612-090211.jpg

But here's another graphic from a more typical recent day. You can immediately see the impact of the variable cloud cover, and the total energy production at 13kWh was less than half what was achieved on the sunny day.
Screenshot_20170612-090917.jpg
 
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you could keep a power bank topped up i imagine, i have a 10,000mah one from a few years ago a POWER ROcks one we bought for going to Bali a few years ago.
However looking at cost i think it would be much more expensive than simply charging a biggy at home once a week.
 
StewartR said:
Not enough information provided. The basic relationships you don't seem to have taken into account are:
* power = voltage x current (eg 1mW = 1V x 1mA)
* energy = power x time (eg 1kWh = 1kW x 1h)

Firstly, how many Volts is the power bank rated at? Its energy storage capacity is a number of mWh, which you get by multiplying the 26,000mAh by the voltage. So for example my phone battery is 2550mAh, but it runs at 3.85V, so the energy storage is 2550 x 3.85 = 9817mWh = 9.8Wh.

Secondly, how many Watts are the solar panels rated at? The 5V or 15V you mentioned are the output voltages, but you need to know what power they generate, measured in Watts. The solar panels on my roof are rated at about 250W per square metre, so that should hopefully help you work out whether you have the decimal point in roughly the right place. (Though I expect a portable panel won't be anywhere near as powerful.)

So then if you know the energy storage capacity of the power bank in Watt-hours, and you know the power output of the panel in Watts, divide the storage capacity by the panel output to work out how many hours it will take to charge the power bank.
Click to expand...

It's concise statements like these that make me think, I did a good job posting here !

The power bank in question is a Anker Astro E7 rated at 26'800mah. It's input is 5V/2A and it's output is 5V/4A (Total). I believe it has 2 2 amp usb outlets hence the total (I could be wrong on that).

In relation to the Solar Panel, I'm still thinking specifically which panel to get, I don't exactly intend to get something cheap off eBay like those cheap £1.99 panels but since I'll be charging a power bank I won't be going for something to heavy. I was thinking of the Anker Solar PowerPort. It's advertised output is 5V/ 3A. I believe the panel is rated at 21W.

Its worth noting, I'm not doing this for the sake of saving a few £££s. It's more so experimentation plus in a few months, I'll be visiting Asia and some of the places I'll be visiting are rural and as such, electricity will be scarce so I'm thinking this will be a good circumnavigation for that problem. I remember someone telling me, they have a solar panel on the sunroof of their car and it chargers a power bank and it comes in quite handy.
 
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Could the answer be a couple or more power banks?

I thought about buying a wee solar panel for camping (Scotland) but due to the obvious lack of sunlight we get here I wonder if the answer is cheap electricity at source, then stored? I've not done the sums yet or compared the weight or bulk of power banks vs panel sizes. Obviously the key factor is the 'source' as I'd never be away more than a week from the car 12v or mains 240v.

I currently use a 10,000mAh bank from Amazon, cost me about a tenner. I guess four of these would have the equivalent footprint of a similarly priced folding panel regarding rucksack space.

You can also get folding panels that output enough for a laptop.

https://www.amazon.co.uk/d/5fn/KING...4OGG/ref=sr_1_1?ie=UTF8&qid=1497342278&sr=8-1
 
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Professor1991 said:
The power bank in question is a Anker Astro E7 rated at 26'800mah. It's input is 5V/2A and it's output is 5V/4A (Total). I believe it has 2 2 amp usb outlets hence the total (I could be wrong on that).

In relation to the Solar Panel, I'm still thinking specifically which panel to get, I don't exactly intend to get something cheap off eBay like those cheap £1.99 panels but since I'll be charging a power bank I won't be going for something to heavy. I was thinking of the Anker Solar PowerPort. It's advertised output is 5V/ 3A. I believe the panel is rated at 21W.
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Hmmm. Anker have a good reputation, but they are rather vague when it comes to advertising precise specifications.

For example they say the Solar PowerPort is rated at 21W, but its maximum output is 5V/3A which is 15W. I'm not sure what the 21W figure means. If I had to guess, I'd suggest that the panel could deliver 21W in ideal conditions - i.e. bright sunshine, with the panel orientated exactly perpendicular to the sun's rays. That would imply that it would be capable of delivering its maximum output of 15W even when the conditions weren't quite ideal. (And presumably when conditions are ideal, some internal circuitry limits the output to 15W and the rest is dissipated as heat, or something like that.)

When we're looking at capacity, I think Anker assume everything runs at 5V. So the capacity of the Astro E7 power bank is 26,800mAh x 5V = 134,000mWh = 134Wh. As you say its input is 5V/2A which is 10W, so it will take at least 13.4 hours to fully charge - more if the charger isn't delivering the full 2A.

If we want to gauge how the power bank would work in connection with the solar panels, I think my experience of the panels on my roof is relevant. (See graphics in previous post). My panels are rated at 4kW, but on that sunny day at the end of May the most they delivered was about 80% of that, and averaged over the entire sunny day the output was about 40-50% of that. So with the Anker panels, with a capacity of 21W, you might reasonably expect to get about 8-10W averaged over the whole day, if you put them on my roof (azimuth angle 20° from south, slope 22°). If you laid them out on a horizontal surface you'd get a bit less; if you hung them on the back of a rusksack as in the Anker illustration you'd get a lot less; if you were using them oop North instead of in Maidenhead where I am you'd get less; and of course if it's not sunny or not summer you'd get a lot less.

So if you laid out the panels on a suitably inclined south-facing surface, in the south of England in the summer, this implies it would take a full sunny day to fully charge the power bank. That's the best case for the UK. If you wanted these to charge your power bank whilst hiking in Death Valley, say, things would be a bit different.
 
Putting Solar to one side. What are peoples views on wind power ?

What if I was to get some type of fan and connect it to a power bank, would this in theory work ? I'm merely inquiring about the wind as I'm just interested.
 
Professor1991 said:
Putting Solar to one side. What are peoples views on wind power ?

What if I was to get some type of fan and connect it to a power bank, would this in theory work ? I'm merely inquiring about the wind as I'm just interested.
Click to expand...
My first thought is that a wind turbine small enough to be portable wouldn't generate enough power to be useful.

My second thought was to research it, and I found this page with lots of numbers.
http://www.greenspec.co.uk/building-design/small-wind-turbines/

There are some useful worked examples about 2/3rds of the way down the page. You can extrapolate from them to draw some inferences regarding the size of system you would need.
 
Most useful, as always, I appreciate the reply.

Whats sparked my interest is that, I've recently seen photos of fans/ blades with wiring attached to them. I was thinking, if those wires were connected to the correct electrical conversion/ storage medium. I suppose you could in theory use a PC fan as a wind turbine ? Mount it in the appropriate location and seeing as their fairly quick/ easy to spin, you'd hope they generate electricity. I suppose you could set up multiples of these to generate some electricity worthy of actual use . Benefit of these above solar power I can see is that, they can also function at night as well.

Another thing, I saw a YouTube video of someone essentially testing this (http://www.ebay.co.uk/itm/NEW-DC-5V...hash=item41c459977e:m:mF0cdNuMUaw5YHG-ulh5BNg) and it got me thinking yet again, what if this was put on a drain pipe you have on the walls of your house ? That seems heavily unlikely to produce any real electrical power worthy of use but I suppose the idea in its base form still stands ? What if the piping leading to these water turbines narrows therefore leading to increased water pressure ? <-- If that makes sense ?

This is me just doing some "clever" thinking in my head. My thinking is that if I find these concepts easy to grasp and understand, then I can work upwards from here instead of attempting to understand something I'll probably never get. Start from simple.
 
Professor1991 said:
I suppose you could in theory use a PC fan as a wind turbine ?
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Did you crunch the numbers? (I showed you how.) what kind of power output does the equation give for a fan which is, say, 80mm or 120mm in diameter?
 
These numbers are flying right above me head ! I'd buy you a beer if I could for all the help you've provided thus far but you get why I created the thread and am seeking info more than advice.
 
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