Question about solar panel circuit Answered
I'm putting together a solar powered cell phone charger and I need some advice from someone who knows a thing or two about photovoltaics.
I've spent the better part of my free time the past three days or so absorbing as much information about electrical charging over USB and solar cell output as possible. I've seen a lot of helpful DIYs, and they would be great if I was following their method exactly. Unfortunately my project has serious space and power constraints. It's not for trickle charging an additional battery, it's for providing direct power to a USB phone.
Here are my specifications. I need 5V and preferably ~500mA. Anything over 400mA should work fine. I *think* I've come up with a way to get that within my space requirements but I'm not positive it will work because I'm mixing two different size solar cells in one circuit. I can't seem to find a definitive answer as to whether or not this is OK, and what the results will be.
I've attached a diagram of my plan. Two 5.5V/70mA solar cells wired in parallel with seven 1.5V/50mA cells. If I'm assuming correctly, this will give me an output of 5.5V (before the regulator) and 490mA.
I don't know how or if the lower voltages of the smaller cells will effect the output. Can I use a combination of high voltage and high amperage cells in one circuit to get the output I need?
I've talked with people in the Science and Tech forums and I've gotten a long way on the electrical circuit aspects and USB issues, but I'm hoping someone here will know a thing or two more about solar cells to tell me if my plan is viable as it is or if I will have to modify it.
Thanks for any help.