Well if you really want to implement something like that, then not under the transparent cover but using a replacement cover which is built from these solar panels.
Another point not mentioned here is the impact of the battery health. If you consider a situation, where sun is once there and then it’s away, you will get tons of charge/discharge cycles which could considerable shorten the lifetime of the battery. Imho, using a solar panel for such a power-efficient device like a smartphone is trying to optimize things on the wrong end. There are so much better opportunities to save power than poweringing a smartphone with solar panels.
To implement the emergency scenario, I would rather suggest to configure the phone in such a way that under 5% of battery it will do a shutdown, so if you really have an emergency you will have enough juice to start it once to do your emergency call / gps fix / whatever.
maybe check this out:
it is a solar battery charger with 3rd generation flexible solar cells. Not cheap, no doubt, and another story where you have to wait for your product. But it is really awesome, I think. Another fair use story, maybe. crowdfunding page link
I don’t fully agree. Most Li-Ion batteries have the lowest wear when you try to keep the charge between 30 to 70%. There are a couple of people (e.g. in the Thinkpad forums) who did that and got only around 5% wear after several years and over 1500 cycles. That’s also the strategy which car makers try to adopt for electric cars, so they design the charge electronics in such a way that you can neither fully charge the battery nor fully discharge it.
With that being said: I still doubt that constant “charge/discharge” - like the one discussed here which purely depends on the sun (like let’s say 80 times a day) - will be really healthy for the battery. Especially in the (rather unlikely case) that it will allow you to keep the battery almost full when you are in sunny conditions and no proper charging strategy has been implemented.
But the biggest concern I have with this is really the point which @ben mentioned. To use the sun energy, you need to put your phone in a hot place. And I hope that we all agree that heat (especially when charging) kills batteries much faster.
Dirk (creator of the jolla keyboard) created a similar sort of thing for the Jolla Phone, and with the phone on flight mode or otherwise using as little amount of power as possible he managed to charge about 3% in an hour.
Keep in mind producing solar panels is probably still very energy and resource intensive.
It is only useful if you put them into good use (i.e. into the sun and producing energy!
Assumption below, i have no data to prove that!
Unless you are really a researches or wildlife photographer or out in the wild for other reasons and really, and i mean really!, using such a charging device, chances are you are never producing the amount of energy production, mining, transportation of such devices to your door cost.
I agree with you (only buy it if you really, really need it … the smaller the panel, the lesser the use time = worse). But do you have recent information to back this up? I know this was true a long time ago (that building solar panels often needed more energy than they would ever “harvest” in their lifetime) but is this still true? I’ve never found new information regarding this and in the meantime a lot of new solar panel manufacturing techniques (with new materials) were invented in the meantime. Does anyone here know? I assume this will be still true for the “smaller” panels, but I was not able to find the information.
I love the concept. Finally a nice every day use for the bio solar panels (for which, btw @ben’s argument is obsolete). It’s a little bit expensive, but I hope that it causes enough impact to draw follow up products.
Edit: From the project page: “Inside HeLi-on you find polymer solar cells produces by infinityPV. Polymer solar cells are part of the third generation of solar cells, also referred to as organic solar cells. The light absorbing active material is carbon based, and the entire solar cell is made with renewable and non-toxic materials. The solar cells are printed directly on thin plastic foil using optimized printing machines.”
As far as I remember they are not as efficient as silicon based cells (which is one of the reasons they are not used for big solar collectors), but since the material is so cheap and easy to work with its perfect for applications with don’t need much energy.
I want to make a solar-cover as well. Therefore I bought a 5V 81mA solar panel which is able to activate the charging process when the phone is turned off. But now I have another problem: How can I connect the pins to the solar panel? They are so incredibly small that for me it is nearly impossible to make some kind of counterparts to mount on the FP2 cover. Can someone of you give me some advice?