As the input impedance of the power management circuit is extremely large it is possible to power projects from unusual sources.
In this example I have used a series of LEDs to power a Bluetooth low energy board that transmits temperature measurements. When hit by direct sunlight the LEDs produce about 50nA of current at 0.5V. By combing them in series and parallel it was possible to produce sufficient power to run an application.
With 12LEDs placed in the sun I was receiving wireless packets to my phone every few minutes. With this power management circuit it was possible to turn Light Emitting diodes into solar cells.