The principle of solar street light

As a kind of sustainable renewable energy, the prospect of solar energy is very impressive. It can be used wherever the sun shines. In the lives of ordinary people, except for solar water heaters, solar street lights, and Some emergency road signs, buoys, etc.

Some friends may have such a question, why is there a solar panel, under the conditions of sufficient sunlight, there will be electricity generation? Next, Chang Hui will answer this question for everyone.

Solar panels generally use devices that are responsive to light and can convert light energy into electricity. The common one is silicon. This is one of the most abundant materials on our planet. It has semiconductor characteristics. It laid the foundation for the photoelectric conversion process of solar panels.

But the first thing to understand is that the conductivity of pure silicon is very poor. There are no freely moving electrons in the crystal structure. To enhance its conductivity, pure silicon is usually doped with trace impurities. , Enhance its conductivity, according to this characteristic, it can be made into different conductive devices.

For the silicon used to make solar panels, phosphorus or boron is usually added to it. When boron is added, the silicon crystal will form a hole, because the original silicon atom is surrounded by 4 electrons, and the boron atom is around There are only 3 electrons. After being mixed into the original crystal structure, holes will be generated. This hole has no electrons and is very unstable. It is easy to absorb other electrons to form a P-type semiconductor.

After the phosphorus impurity is doped into the silicon crystal, because there are 5 electrons around the phosphorus atom, the extra electron will be very active, forming an N-type semiconductor. There are many holes in the P-type semiconductor and the N-type semiconductor. There are many active free electrons. When the two are in contact, these free electrons will find holes and fill them up. The contact surface between the two will form a potential difference, that is, a PN junction. The P-type side has positive and negative Electricity, N-type side is positively charged.

When light is received, the energy contained in the light will be transferred to the semiconductor. This energy will loosen the structure of the electrons and allow them to move freely.

This is because light energy will separate the electron-hole. Normally, a photon with a certain energy will release an electron, which happens to form a free hole. If this happens to happen on the contact surface Nearby, when attracted by the built-in electric field, electrons will flow into the n zone, and the holes will flow into the P zone to form a current from the N-type zone to the P-type zone. The power plant of the battery forms a voltage, which also forms electrical energy. Charging function.