Photovoltaic will usher in the first year of 1500V large-scale application

"Since the second half of 2015, the 1,500-volt system has been frequently mentioned by people in the photovoltaic industry, and some companies have even launched 1,500-volt products in advance." Jiang Hao, project manager of the New Energy Department of Shanghai Electric Power Design Institute, pointed out at the "Reliability and Economic Analysis Seminar on Technical Solutions for Photovoltaic Power Generation Grid-Parity Projects" held on April 18 that the 1,500-volt system plays a leading role in reducing costs and increasing efficiency, can effectively buffer the impact of subsidy reduction, and start a new engine for photovoltaic grid parity.

1500V system becomes a new engine for affordable grid access

China has achieved global leadership in the photovoltaic manufacturing industry, but has not been able to immediately apply some advanced technologies after development. As early as 2015, photovoltaic inverter manufacturers represented by Sungrow launched 1500-volt voltage levels and over-matching solutions, but to this day, technologies such as 1500 volts, over-matching, and 72-cell large modules, which are "standard" technologies in other countries, have not been widely used.

It is understood that the main reason for this phenomenon is that the developers, designers and holders of my country's photovoltaic projects are not the same entity. For the holders, they only require a fixed rate of return and are not very enthusiastic about pursuing technological progress. In addition, the mentality of investment companies tends to be stable and they have not really achieved data-based operations. At the same time, the design department lacks profits and innovation motivation, which together have led to the current development trend.

In the "2019 China Photovoltaic Grid Parity Industry Report" released at the conference, Zhixin Research Institute pointed out that with the advancement of grid parity, companies have been under bidding pressure for a long time, and this situation is expected to be resolved this year.

This year's National Energy Administration's "Notice on the Relevant Requirements for the Construction and Management of Wind Power and Photovoltaic Power Generation in 2019 (Draft for Comments)" shows that competitive bidding projects will account for a large proportion of ground power stations and industrial and commercial power stations in 2019. The fierce bidding mechanism will inevitably force companies to achieve the ultimate in power station design, construction and operation and maintenance, otherwise some companies will be "eliminated" from the competition.

"The upgrade of photovoltaic systems from 600 volts to 1000 volts has brought about a reduction in costs and an increase in power generation. When 1000 volts are upgraded to 1500 volts, the efficiency of photovoltaic systems will also be greatly improved." Jiang Hao pointed out at the meeting that my country's photovoltaic power generation subsidies will be reduced year by year, and the overall cost reduction space of the 1000-volt DC system is limited. Upgrading to 1500 volts will be a revolution. The 1500-volt system, which has both cost reduction and efficiency improvement functions, may become an effective solution to reduce the cost per kilowatt-hour.

Industry insiders pointed out that around 2015, domestic manufacturers such as Sungrow, TBEA, Huawei, and overseas manufacturers such as GE, PE, and SMA successively launched 1500V voltage level system solutions. This technology was first applied to foreign power station projects, and with lower BOS costs and lower losses, it has become an important force in helping global photovoltaic power stations move towards parity. The application of the new "1500V voltage system + large array + high super matching" technology can make the power generation curve smoother, making new energy a more stable energy source, and at the same time reduce the photovoltaic power cost by more than 5%.

"Balanced grid-connected projects in overseas markets have basically applied 1500V photovoltaic system solutions." Bian Changle, general manager of Huawei Smart Photovoltaic China Solution Sales Department, pointed out at the meeting that in the global trend of "balanced grid connection", 1500V photovoltaic system solutions have become the first choice for overseas markets.

In addition, although the mature 1500V technology is a cost-reduction tool for the photovoltaic industry, it also poses a challenge to the safety of photovoltaic electrical systems. It is understood that since this technology increases the voltage of the photovoltaic system by 1.5 times, the number of photovoltaic modules in a single string has increased by 1.5 times compared with the 1000V technology; and the higher the DC voltage, the more likely it is that dust will accumulate and cause poor insulation. In places where the electrical clearance and creepage spacing are insufficient, it is easier to form electrical breakdown and leakage, thus causing safety hazards such as arcing or electric shock. Once arcing occurs, it is difficult to extinguish due to the high DC voltage and high energy intensity, which may cause fire.

Some people believe that when designing a 1500V system, the DC nodes should be minimized and the DC current should be reduced. Considering these aspects, the inverter of the string type is close to the bracket, the DC path is short, and the electric energy is mainly transported by AC, which is more guaranteed in terms of electrical safety of the 1500V photovoltaic system.

String inverter solutions and other designs based on electrical safety have also become a weapon for 1500-volt solutions to compete in the global market. Previously, GE of the United States conducted research and analysis from the aspects of system cost, power generation, and LCOE, and believed that 1500-volt DC voltage is the best voltage for photovoltaic power stations. First, more components can be connected to each string in the DC 1500-volt component system, which can increase the string length by 50%; secondly, due to the increase in system voltage, the number of components in series increases, the use of DC cables connected to the inverter decreases, and the number of junction boxes can be reduced accordingly; at the same time, the power density of electrical equipment such as junction boxes, inverters, and box transformers increases, the volume decreases, and the workload in transportation and maintenance is also reduced, which is conducive to reducing the overall cost of photovoltaic systems.

Industrial chain supports 1500V system installation

In November 2015, Beijing Jianheng Certification Center issued the "1500V Photovoltaic Power Station Key Equipment Certification Implementation Rules", and third-party certification agencies such as CQC and T譈V also have relatively mature 1500V related certification access and product test design. After nearly 4 years of development, the 1500V voltage level related standard system has become increasingly mature.

In terms of photovoltaic equipment, in order to adapt to the 1500-volt photovoltaic system, the technology development has also become more mature and perfect. At present, the mainstream domestic component manufacturers all provide a full range of 1500-volt voltage-related products. They have enhanced the insulation and ensured the safety of components by optimizing the component version design, upgrading the backplane material, replacing the junction box and other measures to adapt to the high-voltage electrical shock of the 1500-volt photovoltaic system; in terms of inverters, manufacturers such as TBEA, Huawei, and Sungrow also have rich experience in foreign projects. These domestic manufacturers have launched 1500-volt inverter products adapted to the Chinese photovoltaic market since 2016, such as Huawei's SUN2000HA series.

At the same time, the problems of high-voltage switches and lightning protection have also been solved. Previously, the DC cables required for 1500-volt photovoltaic systems had already been applied on a large scale, and mainstream manufacturers at home and abroad had supplied them, but there were no high-voltage switches of matching specifications, which made it difficult to match the entire system. After the development from 2016 to 2018 and the popularization of 1500-volt photovoltaic systems in overseas markets, the current mainstream switch and fuse manufacturers in China have developed corresponding supporting products, obtained CCC and CE certification, and are in sufficient supply.

It is worth noting that 1500V photovoltaic systems have begun to be used in China. In January 2016, the first 1500V photovoltaic power generation system demonstration project in China, the 30MW photovoltaic project of Golmud Sunshine Qiheng New Energy, was officially connected to the grid for power generation. In addition, Sungrow also invested in the 50MW smart photovoltaic power station of the Shanxi Datong Photovoltaic "Leader" Base in the same year, which has been connected to the grid for power generation. These projects performed well during the grid connection period.

There is reason to believe that if relevant conditions are met, my country's photovoltaic industry will usher in a large-scale "cost reduction" this year. Photovoltaic power stations with a voltage level of 1,500 volts will also become one of the key plans for photovoltaic project construction this year due to their advantages.