I will, as an expert in this field, once again point out this simply will not happen. The physics are against you.

In AM1.5 sunlight, what we get over most of the part of the world that has iProducts, you have 1000 watts of power per square meter of space. Conventional solar cells can capture about 15 to 20 percent of that, and the polymer ones talked about here are about half that. Power conversion will drop another 50% of that. So realistically you're looking at maybe 35 watts per square meter.

The iPhone is about 0.05 square meters. That means it's going to collect a few milliwatts of power. That's less that it draws when in sleep mode, and perhaps the same amount of power that you'd get by plugging it in for 2 minutes or so.

Why bother?

Unfortunately I cannot really picture myself leaving say my iPad or iPhone in the sun for a couple hours to charge. Doesn't really pan out as a "good" idea in my mind as the last thing I would want to happen is the direct exposure from the suns light causing any kind of heat damage, moisture, or sunspots to the screen itself.

Luckily I believe companies such as Energizer have the right idea with their inductive charging technology which allows them to "wirelessly charge" a device. Mind you even that technology has flaws, and is not considered "free energy" unless you perhaps power the charging pad with say um? A solar panel.

I had one of these in 1986 - 25 years ago! And it worked quite well actually.



In the past 25 years surely the tech has advanced enough to drive (or at least top up the charge) on laptop.

You naysayers are looking at this all wrong. This would not initially be to fully power or even truly charge the device. It would be to offset the consumption of power to make the battery possibly last a while longer. If you can get an extra hour would it be worth it to you?

Well, ok, lets take this seriously for a moment, after that little blunder of mine.

Let's take xyz001's tech specs for the solar panels for granted. The biggest (wrong) assumption he is making in that maths is that the back of the iPad will be facing directly to the sun (without even considering clouds!). His numbers would support a vision where we wouldn't need to recharge the iPad at all, ever.

Let's make some less crazy assumptions.

Let's assume that it is in fact viable a 2.5w production of power in these panels. This "2.5" is peak power. Mostly you will have your iPad facing down (specially if it is lying around in any desk). This means that in 80% of the time the solar panel is not doing anything. Let's focus then in usage time. When you are using the iPad, you will be facing it with an angle to the floor, inside some building.

Thus the wattage of light coming into the solar panel will not be 1000 watts per meter, but more on the level of 50-200 watts per meter, depending on where you are, what are you facing, etc. This means that the actual production of the panel will be something between 0.1w and 0.5w. 0.5w in 10 hours is 5.0wh, which is one fifth of the entire energy stored in the battery. It means 2 hours ~ of usage.

So, using the most optimistic numbers ever, we have reached 2 hours of more battery life. And you won't be able to recharge it while facing up (while lying on the desk). This is akin to a few tweaks on the battery levels and the CPU usage, etc. so why bother in the first place? Remind yourselves that far from the better numbers, the average will be more like 20-30 minutes of increased battery, i.e., well within error margin.



There is an exception to this. Imagine that there is this magic "smart cover" that is a thin solar panel. You close your iPad with it and it is facing upwards, lying in a desk. Now that's something better, but nevertheless quite useless (if you are lying it on the desk, why not just docking it and charging it WAY faster??).


So I see no point in here. Only when solar panels get just too cheap to matter, and when CPUs and LEDs use just mind-boggingly low wattages will this have any interest (it might already have for e-ink devices though).