Technically ways to solve this problem there are two: First, the use of thin-film solar cell, the second is the use of concentrator solar cells, reduce dependence on raw material volume. Low conversion rate used thin-film battery, so the new high-power condenser battery system attention by researchers [1]. Concentrator solar cells is convex or parabolic mirrors to focus sunlight to the times, several times or several hundred or even thousands of times, and then projected onto a solar cell. Then the solar cell can produce a corresponding multiple of electrical power. They have a high conversion rate, the battery supplies less small footprint advantages and. High-power condenser battery representative is gallium arsenide (GaAs) solar cells.

　　GaAs belongs to the group III-V compound semiconductor material, which matches the energy gap of the solar spectrum is more suitable, and can heat. Compared to silicon solar cells, GaAs solar cell has better performance

　　Comparison of GaAs cells and silicon photocell

　　1, photoelectric conversion rate:

　　GaAs band gap than the silicon-wide, making it the spectral response and space solar spectrum capacity than silicon good match. Theoretical efficiency of silicon cells was about 23%, while the theoretical efficiency of single-junction GaAs cells reached 27%, the theoretical efficiency GaAs cells and multi-junction of more than 50%.

　　2, temperature resistance

　　Conventionally, GaAs cells temperature resistance better than silicon photovoltaic cells, there are experimental data show that gallium arsenide cells can still work under the conditions of 250 ℃, but at 200 ℃ silicon photovoltaic cells have been unable to operate normally.

　　3, mechanical strength and specific gravity

　　GaAs compared with silicon on the physical properties to be more brittle, which makes their machining easier than when broken, so often put it into a film, and the use of a substrate (usually Ge [germanium]), against its In this regard the negative, but also increases the complexity of the technology.

　　Current Development of GaAs cells

　　GaAs solar cells developed from the beginning of the 1950s, has been more than 50 years of history. In 1954 the world's first discovery GaAs material with photovoltaic effect. In 1956, LoferskiJ.J. And his team investigate the physical properties of the best material for the manufacture of solar cells, they noted Eg material within the range of 1.2 ~ 1.6eV with the highest conversion efficiency. (GaAs material Eg = 1.43eV, in the high-efficiency range, theoretically estimate, GaAs single-junction solar cell efficiency up to 27%). 1960s, Gobat and other developed first a zinc-doped GaAs solar cells, but the conversion rate is not high, only 9% to 10%, much less than 27% of the theoretical value. 1970, IBM company and the former Soviet Union Ioffe Institute of Technical Physics, represented by research units, using LPE (Liquid Phase Epitaxy) technology into heterogeneous GaAlAs window layer, reducing the GaAs surface recombination rate, so that the efficiency GaAs solar cells up to 16%. Soon, the United States HRL (HughesResearchLab) and Spectrolab LPE through improved technology so that the average efficiency of the battery reaches 18 percent, and to achieve mass production, creating a new era of high-efficiency GaAs solar cells [4]. From the 1980s, GaAs solar cell technology has gone from LPE to MOCVD, from homogeneous to heterogeneous epitaxial extension, from single to multi-junction knot laminate structure several stages of development, its growth rate is accelerating, efficiency continue to improve, currently the highest laboratory efficiency has reached 50% (data from the IBM company), industrial production and the conversion rate of more than 30%.