The United States has developed unique three-dimensional solar cells that capture nearly all light, increase PV system efficiency, and reduce size, weight, and mechanical complexity.

A South Korean company has developed a set of high-efficiency spherical solar cells (Figure 2.37), named “Sphe1ar”. This spherical solar cell represents a great leap in the field of solar cell development, which greatly improves the utilization efficiency of solar energy and changes the traditional form of solar energy. While traditional planar solar cells have only one side to collect solar energy, this spherical solar cell can harvest energy in all directions. Small balls with a diameter of 1~1.5mm are embedded in the solar panel, and the entire surface of the ball can collect solar energy. It is understood that this spherical solar cell can not only improve the solar energy conversion efficiency, but also uses less silicon raw material in the production process than conventional panel solar cells.

Sunovia Energy Technology Corporation and EPIR Technology Corporation of the United States have developed a new generation of cadmium phosphide (CdTe) solar cells. Although the solar industry is now dominated by the use of silicon (Si), the application of CdTe is growing rapidly and it is the second most used solar cell material in the world. CdTe is also recommended as the I1-V1 material because it combines two elements from a group in the periodic table containing the group of 6 elements. Expanding usage knowledge and combining 11-VI materials with Si can accelerate the development of high-efficiency, low-cost solar cell systems.

Sunovia Energy Technology Corporation and EPIR Technology Corporation announced in May 2008 that they had made an unprecedented breakthrough in the growth technology of single crystal Cd Te on Si by molecular beam epitaxy (MBE) method, which is called the Cd Te/Si manufacturing process (Fig. 2.38). The two companies discovered this method of producing single crystal silicon CdTe/Si much faster than any previous laboratory has achieved.

This breakthrough paves the way for continuing to move single-crystal epitaxial CdTe/Si toward large-scale manufacturing and commercialization, opening up promising prospects for CdTe/Si-based ultra-high-efficiency solar cells. It is believed that this development result will greatly reduce the manufacturing cost of high-efficiency solar cells based on CdTe, and can also greatly improve the crystalline quality of CdTe production. The improvement in crystalline quality of 3in CdTe wafers is said to be more than two times better than the improvement achieved in a decade. Furthermore, the uniformity improvement of the wafer is even more pronounced.