When talking about solar cells, we are not strange in every living area, highways, and even we can see the solar lights in parks .

And the recent hot shared bicycle also used the solar energy technology.  In the front frame of Mobike bicycles installed with the solar cell, the main part of electricity consumption is the smart lock. The first generation of bike relies on labour that generate power to charge the smart lock, which makes riding more laborious. But now being used the solar power technology, riding will be easier.

So as we can see, so widely used solar technology, what is the working principle? Solar light panel is actually a PN junction composed of two semiconductors. Simply talk about the PN junction, it dopes different elements in the semiconductor silicon , due to the different extranuclear electron number of different electrons, doped with different elements, it will be with excess electrons or holes, that is the formation of p-type semiconductor Or n-type semiconductors. In this case, if combine the p-type semiconductor and the n-type semiconductor, the different electron concentration and the different hole concentration on both sides would move toward the opposite side, which results in an endogenous electric field in PN junction. As shown below.

When the sun shines on the PN junction, it will produce holes or electrons in the P-type semiconductor or N-type semiconductor. Under the action of the endogenous electric field, the holes or electrons will separate quickly. If a loop is formed, would continue to produce current. As shown below.

This is the working principle of the solar panels on the Mobike.