# What kind of solar panel is required to keep a mobile alive forever?

I want to build a webcam from an old mobile and I want it to be solar powered. The phone use a 3.7V lithium-ion battery of 1500mAh capacity. The phone last 24h hours on one charge.

So if I'm right, it is 3.7V * 1.5Ah = 5.55Wh

I found some solar panels that claim to give at 5V a maximum of 260mA.

5.55Wh / (5V * 0.26A) = 4.26 hours needed to charge the battery at full capacity.

In a sunny day, this will be done quite easily. But on a rainy day or cloudy day, how much mA should I expect from the solar panel? Do I need to have a battery that will sustain many cloudy days in a row? What can I do to be sure I will never run out of battery?

[Update]

Here is the number of hours of sun of the actual location:

And the cloud cover information:

• What you are asking heavily depends on where you are setting up the camera. You already did the math, now it's time to grab some weather history, figure out how many cloudy days you want to sustain and size the battery accordingly. One day is probably not enough... Commented Jun 11, 2014 at 8:56
• @VladimirCravero I updated the question to reflect the local weather condition
– Pat
Commented Jun 11, 2014 at 9:10