Photovoltaic Cell Efficiency Explained

Extract

[...] How to Improve the Efficiency of a Photovoltaic Cell? - Grand Oral Introduction The transition to renewable energy sources has become a global priority in the face of current environmental and energy challenges. Solar cells, which convert solar energy into electricity, play a central role in this transition. However, to maximize the impact of photovoltaic technologies, it is crucial to improve their efficiency. The efficiency of a photovoltaic cell is defined as the ratio of the electrical energy produced to the solar energy received, or as the ratio of the electrical power produced to the luminous power received. [...]

[...] Thus, the multi-junction cell offers two major advantages for efficiency. A larger part of the solar spectrum is converted into electricity and there is a reduction in thermal losses. In fact, each layer is optimized for a specific part of the spectrum by absorbing high-energy photons in adapted layers. Multi-junction cells were developed for space applications, for which the key parameter is not the power-to-price ratio but thepower-to-mass ratio (or the power-to-mass ratio (Wc/kg). Conclusion To conclude, if to improve efficiency, my oral only concerned the structure and materials involved, there are however other procedures. [...]

[...] Let's recall that there is an electric current if there is electron circulation. For electrons to be mobile and circulate, they must be in the conduction band. They must gain energy. If the valence and conduction bands overlap, the material is conductive. If not, they are separated by a gap. If it is large, the material is insulating, and if it is small, the material is semi-conductive. Light is a flux of photons. To convert the energy of photons into electrical energy, cells made of semiconductors are used. [...]

[...] This will create a lack of electrons in the N layer and therefore a positive charge, and an excess of electrons in the P layer and therefore a negative charge. There is now an electric field at the junction of these two layers. When photons come to excite the electrons, they will migrate from the P zone to the N zone thanks to the electric field. The electrons in the P layer having left, they will then leave holes, which the neighboring electrons will fill, and so on. [...]

[...] Let's try to understand what happens in the photovoltaic cell. Exposed to the right radiation, valence electrons of silicon atoms become conduction electrons. They vibrate. However, this is not enough to create an electric current. The electric current is a circulation of electrons in a very precise direction. To obtain this current, we will dope the silicon. Doping is an operation that consists of obtaining a surplus of electrons on one side and a deficit of electrons on the other. [...]