Comparison of the main photovoltaic power generation technologies

Solar photovoltaic technology is a technology that converts solar energy into electricity. Its core is a semiconductor material that can release electrons. The most commonly used semiconductor material is silicon. Solar photovoltaic cells have two layers of semiconductors, one for the positive electrode and one for the negative electrode. When sunlight shines on the semiconductor, an electric current is generated at the junction of the two poles. The greater the intensity of the sunlight, the stronger the current. Solar photovoltaic systems can not only operate under strong sunlight, but also generate electricity on cloudy days. Due to the reflection of sunlight, the power generation effect is even better on less cloudy days than on sunny days. 

Comparison of three main photovoltaic cell technologies  

There are three main photovoltaic power generation technologies currently in use: crystalline silicon solar cells, thin-film solar cells and concentrator solar cells. Crystalline silicon cells are the most widely used, accounting for more than 80%; thin-film cells have grown rapidly in recent years, accounting for more than 10%; and concentrator solar cells are used in small quantities. Among these three photovoltaic power generation technologies, the advantages of crystalline silicon cells are high conversion efficiency and small footprint, and the disadvantages are high silicon consumption and high cost, which are more suitable for urban areas; the advantages of thin-film solar cells are low silicon consumption and low cost, and the disadvantages are low conversion efficiency, large investment, large attenuation, and large footprint, which are more suitable for grid-connected power stations and building photovoltaic integration in remote areas; the advantages of concentrator cells are high conversion efficiency, and the disadvantages are that they cannot use scattered sunlight and must use trackers to adjust the system to be precisely opposite to the sun. Currently, they are mainly used in aerospace. It is expected that in the future, photovoltaic power generation will present a situation where multiple technologies coexist and work together to reduce costs. 

Table 1: Comparison of three main photovoltaic power generation technologies 

Although thin-film batteries are not very efficient at present, the conversion efficiency of thin-film batteries with multiple thin layers and multiple pn junctions can reach 40%-50%, so high-efficiency batteries in the future will eventually follow the thin-film technology route. Among various thin-film batteries, only silicon thin-film batteries have abundant reserves of raw materials, are non-toxic and pollution-free, and have more sustainable development prospects. Silicon thin-film batteries can be divided into three types: amorphous silicon thin film, microcrystalline silicon thin film, and polycrystalline silicon thin film. 

Comparison of four major polysilicon technologies  

The main raw material of the most widely used crystalline silicon solar cell is polysilicon. There are four main processes for the production of polysilicon, namely: modified Siemens method, silane method, circulating fluidized bed method, and physical method. Among these four technologies, the modified Siemens method is the most mature and has been widely used. At present, 80% of the global polysilicon production adopts the production route of the modified Siemens method. The disadvantages are high cost and complex by-product recycling technology; the silane method is currently produced by only one company in the United States. The advantage is high quality, but the disadvantage is high risk and high process requirements; the fluidized bed method can improve the utilization rate of raw materials in polysilicon production, and the cost is low. The disadvantage is that the technology is not mature yet. At present, only one company in the United States uses this technology; the biggest advantage of the physical method is low cost, but the disadvantage is that it does not solve the problem of industrial production, the product is not stable enough, and the purity is not enough.