Solar powered cellphone

The conversation about fair telephone operators has inspired me. For those of you who know a little more than me about electriciy and solar power, my post might seem silly, but as I’m totally ignorant as fas as these topics go, here is what my little brain came up with: the problem with mobile phones is that it’s encouraging people to use a lot more electricity than they should in a planet that is trying to encourage it’s inhabitants to save energy. I have a wonderful Texas Instruments calculator that is mainly solar powered. In the 80’s, I had one that was totally solar powered. So I’m wondering whether a mobile phone could use solar power. I started talking about this to a friend that said that he had read somewhere about a phone charger that uses solar power. Do you have any information about this?

I think an independent smart phone powered by internal photovoltaic cells is not efficient becauseost of the time you have your phone in your pocket… I own a solar powered watch, but smart phones are just too energy consuming.

There is Waka Waka, which also has a cooperation with FP going, and they even donate one of their products to developing countries, for each product they sell:
One would have to calculate though how energy consuming the production is, and if it amortizizes in the long run.

I would favor a crank to generate electric energy, just like some torches have them.

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Samsung tried this with their Blue Earth phone some time ago: http://en.m.wikipedia.org/wiki/Samsung_S7550
I know someone who had it. Apparently it wasn’t very practical.

I have a Waka Wake myself (http://waka-waka.com) which works okay with the summer sun here in the Netherlands. Now that it’s less sunny it works a lot less efficient. Also, even under good circumstances it takes a number of hours to fully charge the Waka’s battery, which equates to a little over a single charge for a FairPhone. So in all honesty, even with the Waka I’ve not been able to run my phone completely off of solar power, except for the really sunny days (which, admittedly, we’ve had quite a few of last summer).


Unfortunately I don’t think solar charged phones are useful unless you live in a country when you can leave it in the sun to charge and don’t need to put it in a pocket.

The better way to go is to move to a solar based charger - so you can leave that in the sun all day and then charge your phone from it as and when (which could then be overnight). There are solar charges on the market already so may be worth having a look at them.

I have an older generation of the Solio charger - the new model looks a lot better as it works on micro-usb rather than a proprietary connector as mine does. It has given me many years of good service but for me works best when travelling (UK weather has not permitted me to use this very often).


To me, it seems there’s another problem with a built-in solar charger in your phone: heat. I wouldn’t feel comfortable exposing my phone to high intensity direct sunlight for longer stretches of time. The sun can get pretty hot :slight_smile:


Thanks for your opinions on this topic. I do remember seeing some report about some people wearing caps with solar carptors to charge their phones. Anyway, if people never tried to do something that sounds impossible at first, nothing much would evolve on our planet! I’d like to be able to use my phone without feeling guilty about wasting energy for such a futile reason as making a phone call!

I actually already had a forced shutdown one because I left my FP in the sun. It displayed a temperature warning and turned off.

Me Zoo. It was beeping and beeping and I wondered why it does it. Then I looked at the display and saw the message. It didn’t turn off on its own though… I removed the battery immediately.

My brother just went on a trip to Latin America for several months. In order to always be able to charge his FP1 he has taken a solar"-fuelled" power bank with him. Maybe this could be an alternative, also for home usage. However, one has to take into account the production of such a power bank as well…

You made me look into the matter of hand crank chargers again and I found this website, which sells such devices (there are other corps too, but these look the most promising).

There is one device only for charging, and another, which has a radio too and serves in emergency situations. The author of this article states the following:

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:joy: :grin: I’m mildly excited! A Solio solar charger, if it works on FF2 would be awesome! I work May - Aug at small UK festivals. No power. But a charger panel out in the sun with my phone tucked underneath? Brilliant. I go look… Thanks @Chris_R

On that Solio charger… $70 is a stretch to just try it on a FF2 - particularly when it has special settings for Apple stuff (as their chargers don’t charge my FF2) Has anyone tried one? The detail spec is
" Max Wattage: 5 Watts
Discharge Rate: Fixed 5V, 1,000mAh
Charge Rate: 5-5.5V 450mAh
Charge Time via USB port/wall charger: 4 hours 30 min.
Charge Time via Sun: 8-10 hours "
but I’ve no idea what the first 3 lines mean.

I’m also looking for a solar power bank for the fp2. The Watts, Volt and Ampere talk gets me cross eyed too. Is there anyone who already did some research on this; What are the minimum and/or preferable specs?

No need to get cross eyed. :wink: Here are some posts for you: :slight_smile:

####Bottom line:

  • Fairphone 2 needs 5V, which is USB standard (if the solar power bank has a USB outlet, it will be 5V).
  • Amperage can be 1A to 2A.
  • Watts is simply the product of voltage and amperage, so the charger would be providing 5W to 10W.

Even if it was practical / efficient to have solar cells in smartphones, the other hardware wouldn’t just be resistant enough to heat. If you’ve ever left your phone in the sun for a little too long, it can do serious damage. If the cells are on the back, what if you have a case on your phone? You would also have to put your phone screen-down to expose it, potentially damaging your screen. Logistically very difficult to pull off.

As people have said here, you would be far better with solar powered battery packs or chargers. They are designed to sit in the sun all day. That’s assuming you live somewhere that has enough sun, too. Anyways, it’s definitely something that can occur in the future. They are already making solar powered bike parts like this 3d printed bike light. Maybe 3d printing and solar power (When combined together) could create something special in the near future. Guess only time will tell.

Thanks for your answer. So the ampere makes the charging go quicker or slower, with 2A being quicker than 1A :confused:

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Correct. :slight_smile: I’m not sure, however, what the maximum “speed” (aka amperage) for FP2 is. (It does not support “quick charge”.)

The best i could obtain was 1.3Amps from a “Devilros” 2Amp charger (normaly used for my raspberry Pi).

Little precision about amperage:
The Fairphone 2, like any other phone can be charged from any “current” as long as the voltage is 5 Volts. The current maked on the adpater is just an indication of how much it can supply, but the Fairphone will regulate it and just take what he need
So, if you have a 5V 0.2 Amp charger (like some very old computers) it will wok perfectly, but it will be super long to charge, if you have a 2 amps charger, the FP will just take more or less 1 amp, as its not really designed for more (the 1.3 being probably the absolute maximum).
If you have a 100 amps 5 volt source, it still wont use more than 1 amp.

So a 2amp charger wont necessarily be faster than a 1 amp charger

Whats best for our fairphone ? the ideal charging rate of a Lithium battery is not the lowest one, it’s the half of its capacity : our Fairphone have a 2420mAh battery, so the ideal charge rate is 1.2 amps…so just use a 1amp or more charger if you want to get the maximum durability :slight_smile:

Source : “battery university” and personal knowledge