Innovation leads the future, distributed inverters will become the mainstream of the market

Recently, the "2016 China Energy Development and Innovation Forum" was grandly held in Kunming, Yunnan, under the guidance of the National Development and Reform Commission and the National Energy Administration and hosted by China Reform Newspaper. A grand award ceremony was also held at the same time as the forum. Sineng Electric Co., Ltd. (hereinafter referred to as "Sineng Electric") successfully defended its title and became the only company to win the "2015 Technological Progress Enterprise" award. After the meeting, the reporter interviewed Li Jianfei, vice president of Sineng Electric, who said: "The pattern is derived from history, and innovation leads the future. Distributed inverters will become the mainstream of the market."

Independent research and development leads the photovoltaic industry

In the emerging industry of photovoltaic power generation, unlike most companies, Sungrow Electric did not engage in simple copying or take the shortcut of purchasing technology and then DIY assembly. Instead, it focused on product research and development from the beginning. Therefore, all of Sungrow Electric's products have completely independent intellectual property rights.

"The reason for this choice is that most of the founding team of Sineng Electric came from the world's top 500 power electronics companies, and the R&D team members themselves are senior experts in the power electronics industry." Li Jianfei explained, "The founding team of Sineng Electric has positioned the company's strategy as 'committed to becoming a world-class power supply company'. Only by independent research and development and mastering core technologies can the company be driven to continue to develop."

In August 2014, Sineng integrated the photovoltaic business of Emerson Network Power in the United States, taking over Emerson's advanced technology platform and century-old experience, integrating the hard work of a new innovative enterprise with the experience of a century-old foreign company, and fully realizing the integration with the world's advanced level in R&D, management and marketing.

In January 2015, the National Development and Reform Commission and eight other departments jointly issued the "Energy Efficiency Leader System Implementation Plan", marking the full launch of the PV Leader Program. Sineng Electric became the first PV company to pass the leader professional test and obtain the leader qualification certification. In September of the same year, Sineng Electric was named "China's 2015 PV Leader Outstanding Inverter Enterprise".

Distributed type represents the future development direction of inverters

In the field of photovoltaic power generation, the inverter is the "heart" of the photovoltaic power station, and is responsible for the realization of the core functions of the photovoltaic power station, such as power conversion, grid connection control, power quality, intelligent monitoring, and safety protection. In the photovoltaic power generation system, the inverter MPPT solution determines whether the photovoltaic array can play the maximum efficiency. The conversion efficiency of the inverter is also a key factor in determining the power generation of the photovoltaic power station. The quality of the inverter grid connection control algorithm determines the quality of the power at the grid connection point. The reliability and safety protection measures of the inverter are directly related to whether the photovoltaic power station can operate continuously to the maximum extent. The intelligent monitoring function of the inverter is the basis for realizing the optimized operation of the photovoltaic power station.

In terms of type, photovoltaic inverters are traditionally divided into string inverters and centralized inverters. As inverters become increasingly homogenized, finding more efficient, reliable, durable and safer inverter solutions has become a common concern for the entire industry. Based on its strong technological innovation and R&D capabilities, Sineng Electric has checked and improved existing inverter products one by one, and finally created the third technical route for inverters, that is, the distributed inverter route, which combines the respective advantages of centralized inverters and string inverters. It is known as "the best inverter solution for photovoltaic power stations with higher returns" and represents the future development direction of inverters. "In the future, distributed inverters will become the mainstream of the market." Li Jianfei said confidently.

Li Jianfei told reporters that the main features of distributed inverters are "centralized inverter" and "distributed MPPT tracking", and the value they bring to customers is mainly reflected in three aspects:

First, decentralized MPPT reduces the power generation loss caused by various mismatches of photovoltaic modules. Objectively, various factors such as the dispersion of components, obstruction of the array, and changes in the inclination of the bracket will lead to mismatch losses. In the distributed inverter solution, each intelligent MPPT controller has 4 or 8 MPPT control modules, and each MPPT control module is connected to 4 or 2 strings. Compared with the centralized inverter solution with nearly 100 strings connected to 1 MPPT, the distributed inverter greatly reduces the parallel mismatch loss of the strings. Through the multi-channel MPPT solution, the average power generation income of the system is increased by at least 1.5%.

Secondly, the distributed inverter solution reduces AC and DC line losses. The intelligent MPPT control module (corresponding to the junction box of the centralized inverter) has a voltage boosting function, which increases the DC transmission voltage over long distances (from the junction box to the inverter room) to about 800VDC. Compared with the DC input of about 600VDC of the centralized inverter and the 480VAC AC output of the string inverter, the line loss of the distributed inverter solution is greatly reduced. The AC output voltage of the distributed solution is also increased to about 500VAC, and the AC line loss is also reduced compared to the 315VAC of the centralized inverter. With the distributed inverter solution, the system line loss is reduced by about 0.5% compared to the other two inverter solutions.

Thirdly, the system cost of the distributed inverter solution is basically the same as that of the centralized inverter solution, and has obvious cost advantages over the string inverter solution. The use of distributed inverter solutions to form inverter units of 2MW and above, and the use of 1500V distributed inverter solutions to form 4MW inverter units in the future will have greater advantages in reducing system costs and increasing power generation.

In addition, the distributed solution uses string-level electronic switches and active tripping functions of circuit breakers, which greatly improves system reliability and realizes string-level fault isolation, without affecting the normal power generation of non-faulty strings or MPPT modules. Distributed inverters are also superior to string inverters and centralized inverters in terms of flexible configuration options for capacity ratio. Generally speaking, the distributed solution is a more cost-effective solution that has been widely recognized in the industry and has begun to be applied in batches. It is the preferred solution for the optimization design of photovoltaic power stations.

There is no shortcut to becoming a champion

After years of research, Sineng Electric has achieved excellent results in photovoltaic power generation applications. It has the most complete photovoltaic power station solutions in the industry, including centralized inverter solutions, string inverter solutions, distributed inverter solutions, off-grid inverter solutions, microgrid energy storage solutions and Sineng Photovoltaic Cloud Intelligent Operation and Maintenance Solutions. Among them, my country's most efficient centralized and distributed inverters are both from Sineng Electric, with efficiency rates of 98.32% and 98.34% respectively, which can be said to be double champions, and both products have passed the photovoltaic "leader" certification.

"We are very focused. Over the years, we have invested all our energy in the research and development and optimization of the inverter field. 90% of Sungrow Electric's revenue comes from the sales of inverters. In addition, quality is the lifeline of our company and a principle we have always adhered to. The Ministry of Industry and Information Technology proposed the concept of Chinese efficiency, requiring that the Chinese efficiency of inverters should reach 98%, while our product efficiency has reached 98.32%, ranking at the forefront of the industry. We are also one of the first inverter companies to meet and exceed the standards of the Ministry of Industry and Information Technology," said Li Jianfei.

Since its establishment, Sineng Electric has been ranked the top two in China in terms of PV inverter shipments. In high-end markets such as power generation groups, Sineng Electric has taken the lead. By the end of 2015, Sineng Electric's cumulative shipments exceeded 10GW, ranking second in the industry. Its customer base includes national power generation groups such as State Power Investment Corporation, China Energy Conservation, Huaneng, Huadian, Three Gorges, Guodian, CGN, Datang, Guotou, and China Resources, provincial power generation groups such as Ningdian Power, Yunnan Power, Guangdong Power, Jiangsu Guoxin, Hainan Tianneng, and Qaidam Energy, and excellent private enterprises such as China Minsheng Investment, GCL, Yingli, and Aikang. The installation areas involve harsh environments such as strong wind and sand, high altitude, high temperature, high cold, and high salt fog. Its products are widely used in large-scale photovoltaic grid-connected power stations and distributed photovoltaic power generation projects.