Brief Introduction, Main Characteristics, Main Applications and Market Situation of GaAs Solar Cells

Brief introduction of solar cell

Solar cell is a device that uses photovoltaic effect to convert solar energy into DC energy through semiconductor materials (light energy into electric energy). Commercial solar cells mainly include crystalline silicon solar cells (including monocrystalline silicon and polycrystalline silicon) and semiconductor compound solar cells (mainly gallium arsenide solar cells).

Among these two types of solar cells, crystalline silicon solar cells are widely used in the field of power generation and currently occupy most of the market share; GaAs solar cells are one of the typical representatives of new energy and new materials. Although the photoelectric conversion efficiency is higher than the first two, the highest photoelectric conversion rate in the world has reached 46%; However, gallium arsenide has greater technical difficulty and cost, which is difficult to meet the needs of large-scale production. Therefore, gallium arsenide is mainly used in space vehicle power supply and other high-end applications, and gradually has a small number of applications in ground power generation systems.

Solar cell industry chain

The solar cell industry chain generally includes five main links: battery raw materials, solar cell epitaxial wafers, solar cell chips, solar cell modules and solar power plants.

Main characteristics of GaAs solar cells

Gallium arsenide is more brittle than silicon in physical properties, which makes it easier to crack during processing. Therefore, it is often made into thin films and substrates (often Ge [germanium]) are used to combat its disadvantages in this regard, but it also increases the complexity of the technology.

Compared with other types of solar cells, the process of GaAs solar cells is more complex, especially multi junction GaAs cells. Three junction GaAs solar cells have three p-n junctions, which generally need to grow nearly 30 epitaxial layers. The design of epitaxial structure and the quality of epitaxial growth of each layer directly affect the performance of the whole GaAs solar cells. Therefore, GaAs solar cell industry has certain technical barriers. The following figure shows the advantages and disadvantages of GaAs solar cells.

Main applications and market of GaAs solar cells

From the perspective of specific application, due to the high preparation cost of GaAs solar cells, they are mainly used in space exploration and utilization (mainly used as solar cell panels) and less on the ground (mainly used as high-temperature concentrating solar cells).

Concentrating photovoltaic power station (CPV) is the main application field of ground GaAs solar cells. Concentrating photovoltaic power generation means that the sunlight in a certain area is concentrated in a narrow area through the concentrating system, and the concentrated sunlight is directly converted into electric energy through the photovoltaic effect of semiconductor materials through solar cells. If the concentration multiple is several times to dozens of times, it becomes low-power concentration. If the concentration multiple exceeds 100 times, it is usually called high-power concentration. Gallium arsenide, which can withstand 1000 times the light intensity, is a common material for concentrating photovoltaic at present.

With the reduction of technology and cost, the installed capacity of concentrating photovoltaic power station presents an accelerated development trend. According to his statistics, the cumulative installed capacity of global CPV in 2015 was 254mv, which is expected to reach 1362mw in 2020, with CAGR of 39.91%, significantly higher than the overall growth rate of photovoltaic power stations. The following figure shows the distribution of the global CPV cumulative installed market in 2015.

At present, the United States is the country with the highest photoelectric conversion efficiency of GaAs thin-film solar cells and the largest production base. Its actual output of GaAs solar cells for space and ground concentration accounts for about 50% of the world, and it is a global leader in technology. Emcore and Spectrolab (photovoltaic laboratory under Boeing) It is the world's leading manufacturer of GaAs thin film solar cells.

At this stage, the application field of GaAs solar cells in China is still mainly space applications. The solar cells used on satellites launched in China are completely produced by ourselves. Driven by the development demand of domestic aerospace industry, China has made rapid development in the R & D and production of space GaAs solar cells. The photoelectric conversion efficiency of space triple junction GaAs solar cells has approached the international advanced level.