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?