A miniature solar cell is basically one of the many uses for BPW34 which is a general purpose PiN photodiode that could be used for many sorts of things.
The Solar cell is sensitive to wavelengths ranging between 430-1100nm which really is such a wide range that allows producing power in many different settings. Also, the rated open circuit voltage is 350mV (900nm, 1mW/cm2 light source), on the other hand, the short circuit current is 47μA.
This is highly recommended, since it isn’t just helpful, it’s also fun!
We have used it to produce 0.5VDC open circuit voltage by shining a 940nm infrared LED on one of them. In addition to that, we were able to turn an LED on with them by having 4 of them stringed in series. Last but not least, they could be used for producing small voltage, ~250mV, in a brightly, fluorescent-lit room. Try it yourself and enjoy the experience.
[Product description and pictures courtesy of SparkFun.com]