To meet the new wave of renewable energy under the double carbon target, gd32 injected innovative power into the continuous explosion of the „photovoltaic + energy storage“ industry.
In recent years, the solar photovoltaic and energy storage markets have been extremely hot. According to the report „global market outlook – solar energy 2022-2026“ released by the European Photovoltaic Industry Association, the global new photovoltaic installed capacity from 2019 to 2021 was 117.6gw, 139.2gw and 167.8gw respectively, of which the year-on-year growth in 2020 was 19%, and the year-on-year growth in 2021 was 21%. The Association expects that the global new photovoltaic installed capacity will reach 228.5gw this year, an increase of 36% over last year.
Scale and forecast of global PV annual new installed capacity
Compared with traditional energy generation, solar photovoltaic power generation has the characteristics of intermittency, volatility and randomness. It has basically become a consensus in the industry to improve the power quality and maintain the stability of the power grid by configuring energy storage. With the continuous development of photovoltaic power generation and the steady improvement of penetration rate, household light storage integration has become the mainstream direction of household photovoltaic power generation development in various countries. According to statistics, the global household energy storage installed capacity in 2021 will be 6.6gwh, an increase of 46% compared with 2020. It is expected to reach 9.4gwh this year.
Photovoltaic inverter and energy storage converter are similar in technology and function in the system. Gd32 MCU has been widely used in the field of photovoltaic inverter and energy storage, including inverter control, data monitoring, communication transmission, human-machine interaction (HMI), arc pulling detection and fast shutdown, efficiency optimization, BMS monitoring and protection, photovoltaic accessories and other application scenarios.
Market trend of inverter
And product classification
As the core equipment of the photovoltaic power generation system, the inverter presents a rapid growth trend with the development of the global photovoltaic industry. According to wood Mackenzie’s statistics, the global PV inverter shipment increased from 59.7gw in 2015 to 185.1gw in 2020, with a compound annual growth rate of 25.40%.
Global PV inverter shipments (unit: GW)
According to different technical routes, inverters can be mainly divided into three types, namely, centralized inverter, series inverter and micro inverter.
Large output power, single unit capacity of more than 500kW, mature technology, mainly used in centralized photovoltaic power generation system.
The unit capacity is generally below 200kW, including two sub categories of grid connected series inverter and energy storage series inverter. It has the characteristics of high power density, simple installation and maintenance, and can meet the requirements of indoor and outdoor applications. It can be applied to small-scale power stations and large-scale ground power stations with complex terrain.
The unit capacity is generally below 5kW, with high power density, simple installation and maintenance, automatic adaptation to complex power grid environment, and extended power generation time. At the same time, it also has built-in lightning protection and high-precision leakage current protection, energy storage interface and various communication methods, which are widely used in residential roof, courtyard and other household photovoltaic power generation systems.
At present, the market is mainly concentrated inverter and series inverter. According to public data, in the photovoltaic inverter market in 2021, series inverters accounted for 69.6%, centralized inverters accounted for 27.7%, and micro inverters accounted for about 2.7%. In recent years, with the increasing attention of countries around the world to photovoltaic power generation, such as the introduction of relevant policies to encourage the installation of civil roof photovoltaic systems, and the strong demand for distributed installed capacity, the market penetration of micro inverters is showing a high growth trend, and it is expected to increase to 14% in 2025.
The energy storage inverter integrates the functions of photovoltaic grid connected power generation + energy storage power station. When the electric energy is surplus, it stores the electric energy. When the electric energy is insufficient, it inverts the stored electric energy and outputs it to the power grid. It balances the power consumption difference between day and night and different seasons, and plays the role of peak shaving and valley filling.
How to follow the „light“
The inverter plays an important role in the photovoltaic system, such as AC / DC conversion, power control, parallel / off grid switching and so on. MCU is an indispensable key component in the inverter, and MPPT (maximum power point tracking) is the key technology to maximize the efficiency of photovoltaic power generation.
MPPT is equivalent to the brain of the inverter. It is an automatic optimization process. It can detect the power generation voltage of the photovoltaic module in real time and track the maximum voltage and current value, so that the inverter can track the maximum power point under different sunshine and temperature environments to ensure the maximum output power of the photovoltaic array.
The hardware processing performance and software algorithm of master MCU jointly determine the working efficiency of MPPT, and also the key factor to determine the power generation of photovoltaic inverter. The hardware efficiency is mainly determined by the accuracy of the sampling circuit, the MPPT voltage range, and the number of MPPT channels; Software efficiency is mainly determined by control algorithm. Therefore, in order to meet the requirements of high efficiency and high reliability of the photovoltaic inverter, the main control MCU needs to be equipped with multi-channel high-precision ADCs to collect voltage and current signals, high-precision timers to output PWM control and frequency capture functions, and support hardware multiplier divider, floating-point operation, trigonometric function accelerator and other modules to run control algorithms efficiently.
The purpose of the solar inverter is to extract the maximum power from the solar panel and feed clean energy into the power grid. To ensure this, the power stage voltage and current must be accurately sampled, and pulse width modulation (PWM) needs to be accurately generated for the power switches in DC-DC and DC-AC. In other words, the master MCU must have a high sampling rate ADC module and a high-precision timer to realize these functions.
Typical frame diagram of string inverter
Gd32f47x / 42x Series MCU can rely on arm with main frequency up to 240mhz ® Cortex ®- M4 core, with the advantage of large capacity storage, can efficiently handle the complex control algorithm of inverter. Up to two sets of advanced timers capable of outputting three-phase complementary PWM waveforms and three 12 bit High-Speed ADCs with a sampling rate of 2.6MHz are more helpful to accurately measure the voltage and current of the panel and meet the high-precision control requirements required by the inverter drive circuit.
In addition to the inverter master control, MCU can also be used for communication monitoring and HMI modules within the inverter. The gd32f47x / f42x Series MCU provides a variety of communication interfaces, including up to 8-way USART / UART, 6-way SPI, 3-way I2C, 2-way can bus, Ethernet MAC, USB2.0 full speed and high-speed communication interfaces, and integrates TFT LCD controller and hardware graphics accelerator IPA. It can meet the monitoring and protection of over temperature, over voltage and under voltage of the inverter circuit, as well as the needs of more intelligent control such as communication with the outside world, data collection and transmission, human-computer interaction, etc.
Compared with the energy storage inverter, the grid connected inverter has slightly lower performance requirements on MCU, and the human-machine interaction interface requirements are relatively simpler. Gd32f3 Series MCU can meet the requirements. This is familiar to most engineers, based on arm ® Cortex ®- M4 is a classic mainstream MCU product, providing up to 120mhz main frequency, large capacity storage, multi-channel advanced timer, high-precision ADC, LCD interface and rich communication interface. In many scenarios such as the monitoring module of the inverter, the DTU that collects and transmits the operation data of the micro inverter, and the BMS module, it can be seen that the gd32f3 Series MCU is adopted by the head customers of the photovoltaic industry.
For micro inverters and unidirectional grid connected photovoltaic inverters with obvious growth momentum in recent years, DSP was mainly used to realize sine wave inverter control. Now, under the requirements of supply guarantee and cost reduction and efficiency increase, many inverter manufacturers have started to use high-performance MCU to replace DSP. The gd32e5 Series MCU of Zhaoyi innovation provides a successful case and reference scheme.
Gd32e5 Series MCU has the functional characteristics of traditional DSP controller and adopts arm with main frequency up to 180mhz ® Cortex ®- M33 core, built-in hardware multiplier / divider, provides complete DSP instruction set and single precision floating-point operation unit, and is equipped with hardware trigonometric function accelerator to realize digital signal processing and switching power supply control with enhanced computing power, replacing traditional DSP. In addition, gd32e5 has built-in 90ps ultra-high precision timer (shrtimer) and 5 independent counters, which can generate 5 groups of 2-channel PWM control signals with dead band complementary output, and can be linked with other peripherals to generate high-frequency waveforms required for sine wave inversion.
In addition, Zhaoyi innovation is actively promoting the layout of ultra-high performance MCU products, with arm ® Cortex ®- The M7 core provides processing capacity above 800MHz, supports higher frequency conversion characteristics, and constantly enriches the MCU product portfolio applicable to photovoltaic energy storage systems.
Since last year, the growth rate of the photovoltaic and energy storage market has reached more than 100%, and it is expected to double this year. Especially in the European market, due to the high electricity price, the residents have strong demand for new energy. It is also due to the high prosperity of the photovoltaic and energy storage markets that the shipment volume of MCU has been continuously increased.
Expand the application of photovoltaic accessories to a new „blue ocean“
In the photovoltaic and energy storage system, in addition to the core inverter, a variety of MCU application scenarios can also be found in the peripheral accessories. A variety of photovoltaic accessories solutions have become a useful place for gd32.
The device installed on the photovoltaic panel to turn off the photovoltaic module can quickly reduce the output voltage of the photovoltaic panel to below the safe voltage in case of emergency, thus eliminating the DC high voltage in the photovoltaic system array, avoiding the DC arc and air breakdown to cause fire, and ensuring personal safety.
Gd32e230 Series MCU has the advantages of high cost performance ratio, low power consumption, high ADC sampling resolution, rich peripheral interfaces, etc. it can realize the fast shutdown function by communicating through power carrier. According to the 1:1 ratio of the disconnector and the component, the demand for the disconnector will be increasing in the future.
It is installed between the photovoltaic module and the inverter, and adopts the predicted current and voltage technology to ensure that the photovoltaic module is always in the optimal working state. It mainly solves the problem of mismatch caused by the shielding and inconsistent orientation of the module, which greatly reduces the photovoltaic power generation. It can collect the power generation data (such as electricity, voltage, current and temperature) of photovoltaic modules in real time, and has module level shutdown and management functions to improve safety. At present, the world’s leading inverter enterprises have equipped their products with intelligent photovoltaic optimizers.
Gd32e5 Series High-Performance MCU can replace DSP, run MPPT algorithm to realize maximum power tracking of the module, and realize data acquisition, communication monitoring and fast shutdown functions.
It can reduce the connection line between the photovoltaic module and the inverter in the large-scale photovoltaic grid connected power generation system, and has the characteristics of reliability and easy maintenance. Gd32f303 Series MCU can be used in the monitoring box in the intelligent combiner box to realize the current and voltage diagnosis of photovoltaic modules, arc detection, and RS-485 or wireless networking functions. It can ensure that the photovoltaic system is easy to cut off the circuit during maintenance and inspection, and reduce the scope of power failure when the photovoltaic system fails.
At present, changes in the inverter and energy storage market are driving the next wave of growth of the photovoltaic industry. In the future, intelligent inverters will integrate more high-end technologies. For example, the integration of AI algorithms can enable the inverter to run system diagnosis functions more intelligently and actively and reduce maintenance requirements. The inverter can also connect with other devices to the cloud through the network to provide users with more digital, intelligent and visual home energy management services. The integrated energy system of light storage and charging is gradually developing in the aspects of environmental protection, convenience and safety, which can realize multiple benefits such as photovoltaic power generation, charging operation and power distribution capacity increase. As one of the core components, with the enhanced coverage of Zhaoyi innovation gd32 MCU, it will continue to help the rapid development of photovoltaic and energy storage markets.