High power concentrator photovoltaic cells gradually become the new focus of the field of solar energy

After 30 years of development, the high-power concentrating photovoltaic (HCPV) batteries as the third generation of solar power technology is becoming a new focus of the field of solar energy, causing the industry enterprises in the chase. In good sunlight several European countries, has passed the preferential tariff law and multijunction decline in the popularity and cost of solar cells with 40% conversion efficiency III-V semiconductors, high power concentrating photovoltaic cell market to enter period of rapid growth.

Compared with previous generations battery, HCPV using multi-junction GaAs cell, having a broad spectrum absorption, high conversion efficiency, good temperature characteristics, low energy consumption, manufacturing process, etc., so that it can be a high temperature environment of the high power focusing still maintained in a high solar panel photoelectric conversion efficiency. Higher threshold of high power concentrating photovoltaic system technology and industry span, covering semiconductor materials and process manufacturing, semiconductor packaging, optical design, automation and control, mechanical design and manufacturing, metal processing and other fields. 

HCPV industry products including multi-junction solar cell epitaxial material, the photoelectric converter chip, and the light receiver assembly, condenser, photovoltaic modules, biaxially tracker. Compared with the silicon-based material, based on a group III-V semiconductor multijunction solar cell having the highest photoelectric conversion efficiency, and substantially higher than about 50% of the silicon solar cell.

Group III-V semiconductor having a high temperature characteristics much higher than silicon, and still has a high photoelectric conversion efficiency in the high illuminance and thus can use the high-power converging technologies, which means to produce the same amount of electricity requires little sun Battery chip. A unique aspect of the multi-junction technology is material - can choose a combination of different materials so that their absorption spectra and the sunlight spectrum close to the same the relatively crystalline silicon, which is a huge advantage.

To almost limit (25%) of the conversion efficiency of the latter, while the multi-junction theoretical conversion efficiency of the device is up to 68%. Is currently used most three pn junction is formed by germanium, gallium arsenide, gallium indium phosphide, three kinds of different semiconductor materials, in this multi-junction solar charge controller  not only the lattice constants of these three kinds of material substantially match, and each a semiconductor material having different band gap, respectively absorb the different bands of the sunlight spectrum, which can be full spectral absorption of sunlight.

The concentrating solar cell chip was encapsulated into the light receiver, the receiver package to protect the solar cell, converging light homogenizing the same time play the role of cooling. The receiver assembly further comprises a bypass diode and the lead terminals. Chip reflow welding process and eutectic solder, the two most important difference is that the former uses flux welding, need to be cleaned to remove flux residue after soldering, the eutectic solder flux solder lug.

Gold band bonded to the chip and peripheral circuit connected in order to export electricity from the chip is required. The receiver component test indicators, including the empty rate and electrical performance tests, empty rate is a standard test welding is good or not. Electrical properties, the photoelectric conversion rate of 5.5mm × 5.5mm receiver components in sunlight of 500 times as high as 38.5% or more.

In actual use, also need the receiver assembly and the secondary optics, the radiator package together to form a complete receiver. Secondary optics can reduce the requirement of the high accuracy of the tracker, and more evenly through the Fresnel lens focused spot irradiation to the battery on the chip.