My son is working on his science fair project. I had told him that LED bulbs produce voltage in sunlight and he's been exploring that and is trying to see if he can charge a cell phone using LED bulbs under a light source. Using dozens of small LEDs, he is producing about 5v under a light bulb. He's adapted a usb cord to connect to the LED sources and connected it to his phone but it's not charging and doesn't seem to be producing any current. I'd like to give him some help, but not sure how. Is it possible to use LEDs in this way to power a cell phone? Or is the current so insignificant as to not be a viable solution? Thanks for any help!