When you expose the silicon die of a transistor to a light source a charge is produced. CircuitsDIY opened up a 2n3055 transistor and did some experimenting. With the help of a magnifying glass he was able to built up a charge of 0.65V and produce 42.2mA of current.
Most photovoltaic cells are made of silicon chip above which there resides a very thin layer of noble metal through which around 1% of photon particles enter the material and activates electron flow.
Here I’m showing how to make one simple solar panel using transistor.