Semiconductor technology in solar inverters: future development trends

Semiconductor technology in solar inverters: future development trends

1. Current status of semiconductor technology in solar inverters

1.1 Application of traditional silicon-based semiconductors
Traditional silicon-based semiconductors dominate solar inverters and are widely used and mature. Silicon-based insulated gate bipolar transistors (IGBTs) are the core power devices of centralized inverters, with high current carrying capacity and good switching performance. Data shows that the market share of silicon-based IGBTs in centralized inverters exceeds 90%. Its operating voltage range is usually between 600V and 1200V, which can meet the high power requirements of large-scale photovoltaic power stations. However, silicon-based semiconductors have limitations in high-frequency, high-temperature and high-voltage applications. For example, high switching losses are generated during high-frequency switching, which limits the power density improvement of the inverter.

1.2 Application of silicon carbide semiconductors
The introduction of silicon carbide (SiC) semiconductors has brought significant technological breakthroughs to solar inverters. SiC has wide bandgap characteristics and can operate at higher voltages, frequencies and temperatures, greatly improving the power density and efficiency of inverters. For example, the switching frequency of the inverter using SiC MOSFET can be increased to more than 100kHz, which significantly reduces the use of passive components such as inductors compared to the 20kHz of traditional silicon-based IGBTs, and reduces the size of the inverter by about 30%. In addition, the on-state voltage drop of SiC devices is low, and the efficiency advantage is obvious under high load conditions. At present, the application of SiC semiconductors in string inverters is gradually increasing, and the market penetration rate has reached 15%, and is showing a rapid upward trend. With the maturity of technology and the reduction of costs, SiC is expected to occupy a more important position in the field of photovoltaic inverters in the next few years.

1.3 Application of Gallium Nitride Semiconductors
The application of gallium nitride (GaN) semiconductors in solar inverters is still in its infancy, but its potential is huge. GaN devices have higher switching frequencies and lower switching losses, and can operate in the megahertz range, further improving the power density and efficiency of the inverter. However, the maximum reverse voltage of GaN semiconductors is currently only 650V, which limits its application in high-power photovoltaic inverters. At present, GaN semiconductors are mainly used in small and medium-power photovoltaic inverters, such as micro inverters and some string inverters, with a market share of about 5%. In the future, with the continuous advancement of GaN technology and the reduction of costs, its application scope in photovoltaic inverters is expected to expand further.

2. Technology development trend

2.1 Pursuit of high power density and high efficiency
With the growing global demand for clean energy, the power density and efficiency of solar inverters have become key technical indicators. High power density means achieving higher power output in a limited space, which is crucial for large-scale photovoltaic power stations and distributed photovoltaic power generation systems. Data shows that the power density of inverters using silicon carbide (SiC) semiconductors is about 80% higher than that of traditional silicon-based IGBT inverters, mainly due to the wide bandgap characteristics of SiC materials, which enable them to operate at higher voltages, frequencies and temperatures. For example, the on-state voltage drop of SiC MOSFET is low, and the efficiency advantage is obvious under high load conditions. Compared with traditional silicon-based IGBT solutions, the overall system efficiency of inverters using SiC MOSFET can be increased by about 3%. In addition, SiC devices have low switching losses, which can effectively reduce the loss of energy during the conversion process and further improve the efficiency of the inverter. In the future, as SiC technology continues to mature and its cost decreases, its application in high power density and high efficiency inverters will be more extensive.

2.2 High switching frequency and miniaturization development
High switching frequency is one of the key factors to improve inverter performance. Higher switching frequency can reduce the use of passive components such as inductors, thereby achieving miniaturization and lightweight of inverters. For example, the switching frequency of inverters using SiC MOSFET can be increased to more than 100kHz, which significantly reduces the volume and weight of passive components such as inductors compared to the 20kHz of traditional silicon-based IGBTs, reducing the size of the inverter by about 30%. In addition, gallium nitride (GaN) semiconductors have a higher switching frequency and can operate in the megahertz range, further improving the power density and efficiency of the inverter. Although the current maximum reverse voltage of GaN semiconductors is only 650V, which limits their application in high-power photovoltaic inverters, they have great potential for application in small and medium-power inverters. With the continuous advancement of technology, the reverse voltage and current carrying capacity of GaN semiconductors are expected to be further improved, thereby expanding its application range in photovoltaic inverters. In the future, high switching frequency will become an inevitable trend in the development of solar inverter technology, driving the inverter to be smaller, lighter and more efficient.

3. Market demand and application expansion

3.1 Growth in demand for distributed photovoltaic power generation
Due to its flexibility and efficiency, the market demand for distributed photovoltaic power generation systems continues to rise. According to a report by the International Energy Agency (IEA), the world will increase its installed capacity of renewable energy by more than 5,500GW between 2024 and 2030, and solar photovoltaic power generation will account for 80% of the global growth in renewable energy power generation. Among them, distributed photovoltaic power generation systems, such as rooftop solar power generation, have become a market hotspot because they are suitable for scenarios such as homes and commercial buildings. Data show that the global new installed capacity of distributed photovoltaic power generation will increase by 30% year-on-year in 2023, and it is expected that by 2030, distributed photovoltaic power generation will account for more than 40% of global photovoltaic installations.
The rapid development of distributed photovoltaic power generation systems has put forward higher requirements for solar inverters. String inverters and micro inverters have become the first choice for distributed photovoltaic power generation systems because of their flexibility and easy installation. String inverters can track the maximum power peak of 1-4 photovoltaic strings separately, and can combine solutions of different power levels according to application requirements to meet the needs of distributed photovoltaic power generation of different scales. Micro inverters are mainly used for residential power generation, and are also widely used in power supply of urban infrastructure such as street lights and traffic lights. They have huge market potential. Data shows that the newly installed capacity of string inverters and micro inverters has exceeded that of centralized inverters in 2023, and this trend is expected to continue in the next few years.

3.2 Demand for energy storage system integration
With the large-scale application of solar photovoltaic power generation, the demand for energy storage system integration is growing. Energy storage systems can effectively solve the intermittent and instability problems of photovoltaic power generation and improve the reliability and flexibility of power systems. According to data from the China Business Industry Research Institute, the market size of China's energy storage inverters will be approximately RMB 5.95 billion in 2022, a year-on-year increase of 93.81%, and approximately RMB 10.44 billion in 2023. It is expected that the market size will exceed RMB 12 billion in 2024.
As the core equipment of the energy storage system, the energy storage inverter needs to have efficient energy conversion capabilities and stable operating performance. The application of semiconductor technology in energy storage inverters is crucial. For example, the wide bandgap characteristics of silicon carbide (SiC) semiconductors enable it to operate at higher voltages, frequencies, and temperatures, greatly improving the power density and efficiency of energy storage inverters. The energy storage inverter using SiC MOSFET can increase its switching frequency to more than 100kHz, which significantly reduces the use of passive components such as inductors compared to the 20kHz of traditional silicon-based IGBTs, reducing the size of the inverter by about 30%. In addition, SiC devices have a low on-state voltage drop and obvious efficiency advantages under high load conditions. Compared with traditional silicon-based IGBT solutions, the overall system efficiency of energy storage inverters using SiC MOSFET can be improved by about 3%.
In the future, with the continuous growth of the energy storage market and the continuous advancement of technology, the market demand for energy storage inverters will continue to expand. The continuous innovation of semiconductor technology will provide strong support for the performance improvement of energy storage inverters, promote the widespread application of energy storage systems in solar photovoltaic power generation, and further promote the sustainable development of renewable energy.

4. Competitive landscape and enterprise layout

4.1 International enterprise technology advantages and market position
International enterprises occupy a leading position in the field of solar inverter semiconductor technology, and have formed a strong competitive advantage with deep technical accumulation and extensive market layout.
Technical advantages: International giants such as Infineon and ABB have invested heavily in semiconductor technology research and development. Their silicon-based IGBT technology is mature and has excellent performance. It is widely used in centralized inverters with a market share of more than 90%. In the field of wide bandgap semiconductors, international enterprises are also at the forefront. For example, Infineon's silicon carbide (SiC) semiconductor devices have been commercialized. The switching frequency of its SiC MOSFET can reach more than 100kHz, the on-state voltage drop is low, and the efficiency advantage is obvious, which has promoted a significant increase in the power density of the inverter. In addition, international companies are also actively exploring gallium nitride (GaN) semiconductor technology. Although the application of GaN in photovoltaic inverters is currently limited by reverse voltage, its potential in the field of high-frequency switching has been verified. Some international companies have launched GaN-based small and medium-power inverter products, with a market share of about 5%.
Market position: International companies dominate the global solar inverter market, and their products are widely used in large-scale photovoltaic power stations and distributed photovoltaic power generation systems. For example, ABB's centralized inverters are widely used in large-scale photovoltaic power station projects around the world. With its high power output and stable performance, it has won the trust of many internationally renowned photovoltaic developers. Infineon's semiconductor devices provide core components for many inverter manufacturers, and its market share occupies an important position in the international market. With their technological advantages and brand influence, international companies not only have an advantage in traditional markets such as Europe and the United States, but also actively deploy in emerging markets and continuously expand their market share.

4.2 Technological breakthroughs and market expansion of domestic companies
Domestic companies have made significant progress in the field of solar inverter semiconductor technology in recent years. Through technological innovation and market expansion, they have gradually narrowed the gap with international companies and formed a good development trend.
Technological breakthroughs: Domestic companies such as Sungrow Power Supply and GoodWe have continuously invested in inverter research and development and achieved a number of technological breakthroughs. Sungrow Power Supply has made important progress in the application of silicon carbide (SiC) semiconductors. Its SiC MOSFET-based string inverter has increased power density by about 80%, system efficiency by about 3%, and performs well under high load conditions. GoodWe is actively exploring gallium nitride (GaN) semiconductor technology. The GaN inverter it developed performs well in small and medium power application scenarios, with high switching frequency and low loss, providing an efficient solution for distributed photovoltaic power generation systems. In addition, domestic companies are also constantly improving in semiconductor material research and development, device manufacturing processes, etc., gradually improving their independent innovation capabilities and reducing their dependence on imported semiconductor devices.
Market expansion: Domestic enterprises have rapidly risen in the domestic market and actively expanded overseas markets by virtue of technological progress and cost advantages. Sungrow's inverter products have been exported to more than 50 countries and regions around the world. Its full spectrum of photovoltaic inverters covers a power range of 3kW-3MW, meeting the needs of different application scenarios. GoodWe, Jinlong Technology and other companies have also achieved remarkable results in overseas markets, and their products are popular in markets such as Europe, the United States, and Australia. Domestic enterprises have gradually expanded their market share and competed with international companies by providing cost-effective inverter products and high-quality services. At the same time, domestic enterprises have actively laid out in the field of distributed photovoltaic power generation systems and energy storage system integration to meet the market demand for efficient and flexible photovoltaic solutions, further promoting market expansion.

5. Challenges and coping strategies

5.1 The difficulty of balancing cost and reliability
While pursuing high performance, semiconductor technology in solar inverters faces the difficulty of balancing cost and reliability. Although wide bandgap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) can significantly improve the power density and efficiency of inverters, their cost is relatively high. For example, the price of SiC MOSFET is 3-5 times that of traditional silicon-based IGBT, which to a certain extent limits its large-scale application. In addition, the reliability of new semiconductor devices in long-term operation under harsh environments such as high temperature and high humidity still needs to be verified. Data shows that the failure rate of some inverters using new semiconductors in extreme environments is about 10% higher than that of traditional inverters. To solve this problem, companies need to increase R&D investment, optimize device manufacturing processes, and reduce material costs. At the same time, through strict environmental adaptability testing and reliability evaluation, ensure the stable operation of new semiconductor devices under various working conditions.

5.2 Need for improvement of standards and certification systems
With the rapid development of solar inverter technology, the existing standards and certification systems can no longer meet market demand. At present, there is a lack of unified standards for the application of wide bandgap semiconductors in inverters internationally, and there are also differences in certification requirements in different countries and regions. This not only increases the R&D and market access costs of enterprises, but also makes it difficult for users to choose suitable products. For example, the European CE certification and the American UL certification have different requirements for the electromagnetic compatibility and safety of inverters. Enterprises need to conduct tests and certifications separately, which increases time and economic costs. In order to improve the standards and certification system, the International Organization for Standardization and certification agencies of various countries should strengthen cooperation to formulate unified technical standards and certification specifications for wide bandgap semiconductor inverters. At the same time, enterprises are encouraged to participate in standard formulation to ensure the scientificity and practicality of the standards and promote the healthy development of the solar inverter industry.

6. Summary
The semiconductor technology in solar inverters is in a critical period of rapid development, and its future trends show multi-dimensional characteristics, covering multiple aspects such as technology upgrades, market demand, competitive landscape, and challenges faced.

From the perspective of technological development trends, the pursuit of high power density and high efficiency is the core driving force. Silicon carbide (SiC) semiconductors, with their wide bandgap characteristics, significantly improve the power density and efficiency of inverters. Compared with traditional silicon-based IGBTs, the overall system efficiency of inverters using SiC MOSFETs can be increased by about 3%, and the power density can be increased by about 80%. High switching frequency and miniaturization have also become an inevitable trend. The high-frequency characteristics of SiC and GaN semiconductors have greatly reduced the size of inverters. The switching frequency of SiC MOSFET can reach more than 100kHz, which is significantly reduced compared to the 20kHz of traditional silicon-based IGBTs. The use of passive components such as inductors has been significantly reduced, reducing the size of inverters by about 30%.
In terms of market demand, the rapid growth of distributed photovoltaic power generation systems has become the main driving force. According to the International Energy Agency (IEA) report, the world will add more than 5,500GW of renewable energy installed capacity between 2024 and 2030, and solar photovoltaic power generation will account for 80% of the global renewable energy power generation growth. Among them, the market demand for distributed photovoltaic power generation systems continues to rise due to their flexibility and efficiency. In 2023, the global new installed capacity of distributed photovoltaic power generation increased by 30% year-on-year. It is expected that by 2030, distributed photovoltaic power generation will account for more than 40% of global photovoltaic installations. The demand for energy storage system integration is also growing. In 2022, the market size of China's energy storage inverter market was about 5.95 billion yuan, a year-on-year increase of 93.81%, and in 2023 it was about 10.44 billion yuan. It is expected that the market size will exceed 12 billion yuan in 2024.

In terms of competition, international companies are in the leading position in the field of solar inverter semiconductor technology, such as Infineon and ABB. Their silicon-based IGBT technology is mature and has excellent performance, with a market share of more than 90%. They are also at the forefront in the field of wide bandgap semiconductors. Infineon's SiC MOSFET switching frequency can reach more than 100kHz, with low on-voltage drop and obvious efficiency advantages. Domestic companies have made significant progress in recent years. Companies such as Sungrow Power Supply and GoodWe have made important breakthroughs in the application of silicon carbide (SiC) and gallium nitride (GaN) semiconductors. The string inverter based on SiC MOSFET launched by Sungrow Power Supply has increased power density by about 80% and system efficiency by about 3%. The GaN inverter developed by GoodWe performs well in small and medium power application scenarios, with high switching frequency and low loss.

However, semiconductor technology in solar inverters also faces many challenges. The problem of balancing cost and reliability is prominent. The price of SiC MOSFET is 3-5 times that of traditional silicon-based IGBT. The failure rate of some inverters using new semiconductors in extreme environments is about 10% higher than that of traditional inverters. There is an urgent need to improve the standards and certification system. There is a lack of unified standards for the application of wide bandgap semiconductors in inverters internationally. There are differences in certification requirements in different countries and regions, which increases the R&D and market access costs of enterprises.

In summary, while pursuing high performance, high efficiency and miniaturization, semiconductor technology in solar inverters needs to balance cost and reliability, improve standards and certification systems, and cope with the rapid growth of market demand and fierce competition.