Why should we vigorously develop solar photovoltaic power generation?
What is solar energy, I believe that many people have a general understanding of solar energy to explain the related technologies of solar energy application. Let's talk about photovoltaic power generation in solar energy application technology. There are two main aspects: principle and advantages.
The photoelectric effect can occur in liquid and solid materials, but only solids (especially semiconductor PN junction devices) have higher photoelectric conversion efficiency under sunlight. Using the principle of photovoltaic effect to manufacture crystalline silicon solar cells, the light energy of the sun can be directly converted into electricity. The energy converter of solar photovoltaic power generation is solar cell, also known as photovoltaic cell, which is the foundation and core equipment of solar photovoltaic power generation system. The process of converting solar energy into electricity mainly consists of three steps:
(1) After the solar cell absorbs a certain amount of photon energy, electron-hole pairs are generated in the semiconductor, which are called "photogenerated carriers". The polarities of the two are opposite. Electrons are negatively charged and holes are positively charged.
(2) The photogenerated carriers of opposite polarity are separated by the electrostatic field generated by the semiconductor PN junction.
(3) The light-generating current-carrying electrons and holes are collected by the positive and negative electrodes of the solar cell, respectively, and generate current in an external circuit to obtain electrical energy.
When light hits the surface of the solar cell, part of the photons are absorbed by the silicon material, and the energy of the photons is transferred to the silicon atoms, causing the electrons to undergo transitions and become free electrons, which converge to form a PN junction on both sides potential difference. When the external circuit is turned on, under the action of this voltage, current will flow through the external circuit to generate a certain output power. The essence of this process is the process of converting photon energy into electrical energy.
In a solar power generation system, the total efficiency η of the system is determined by the photoelectric conversion efficiency of the solar cell module, the controller efficiency, the cell efficiency, the inverter efficiency and the load efficiency. At present, the photoelectric conversion efficiency of solar cells is only about 17%. Therefore, improving the photoelectric conversion efficiency of the solar cell module and reducing the unit power cost of the solar photovoltaic power generation system is the focus and difficulty of the industrialization of solar photovoltaic power generation. Crystalline silicon has been the main material since the advent of solar cells. Current research on the conversion efficiency of silicon solar cells has focused on increasing the energy-absorbing surface (e.g., using bifacial cells to reduce reflection), using gettering and passivation techniques to improve the conversion efficiency of silicon solar cells, and - thin cells.