An energy storage system (ESS) is used to collect and store temporarily unused energy in a certain manner, and the stored energy can be extracted to be used when needed or transported to an energy-deficient place for use. In this way, the utilization efficiency of energy is improved and the waste of energy is avoided, which are particularly important in the modern society suffering from energy shortage. This article will introduce you to the concept and development status of ESS, as well as the reference design and various solutions provided by Arrow Electronics.
ESS solves the problem of energy shortage
The generation of energy (such as hydropower, solar power, and wind power among renewable energy sources) is often limited by time and space. For example, hydropower production is usually high in summer, but low during the dry season; solar power can only be generated during the day; wind power generation tends to be affected by seasonal and weather factors, so it is hard to realize continuous and stable power generation. Furthermore, energy utilization by humans is also affected by seasonal and weather conditions, and there are peak hours and off-peak hours for power consumption, to which the above-mentioned power generation methods can hardly adapt.
Therefore, energy storage system equipment for storing surplus energy generated in a period of time, and then supplying it to a power grid during peak hours have become one of the popular applications at present. The energy storage system can store excess heat energy, kinetic energy, electric energy, potential energy, chemical energy, etc., and change the output capacity, output location, and output time. Common energy storage technologies include sensible heat storage technology, latent heat storage technology and chemical reaction heat storage technology.
Sensible heat storage technology stores thermal energy by increasing the temperature of storage medium. Commonly used sensible heat storage materials include water, soil and rock. This is a well-developed energy storage method featuring high efficiency and low cost.
Latent heat storage technology stores thermal energy by means of melting heat generated during the phase change between a liquid phase and a solid phase of an energy storage medium. However, energy storage medium is expensive and tend to corrode, and some of them may produce a decomposition reaction. Furthermore, this technology requires a more complicated storage device compared with the sensible heat storage technology, and has more technical difficulties.
Chemical energy storage technology stores energy by decomposing chemical substances, and the stored energy can be released through chemical combination of the decomposed substances. It can be realized by reversible decomposition reaction, organic reversible reaction and hydride chemical reaction, and is helpful in solving the problem of energy shortage.
Global energy storage market is growing rapidly
Energy storage is a key technology to improve the reliability of power systems and promote the consumption of new energy. The energy storage system can dynamically absorb and store electric energy from a power generation side or a power grid, and release it when needed, thus changing the traditional mode where electric energy production, transmission and use are completed synchronously, making the real-time balanced “rigid” power system more “flexible”, and effectively improving the power quality and power consuming efficiency.
In addition to the energy storage application of large-scale power grid systems, energy storage systems applied to household users (household energy storage) will become an important part of new power systems. This kind of energy storage systems is usually installed together with a household photovoltaic system to provide electricity for household users. In the daytime, photovoltaic electric energy is preferentially used by local loads, surplus energy is stored in a storage battery, and still surplus energy can be selectively incorporated into the power grid. When the photovoltaic system cannot generate electricity at night, the storage battery discharges electricity for the local loads to use. Household energy storage systems encourage users to generate power for their own use by working with household photovoltaic systems, reduce the electricity cost of users, and ensure electricity consumption stability in extreme weather.
A household electrochemical energy storage system usually consists of a battery pack, a battery management system (BMS), a power conversion system (PCS) and an energy management system (EMS), and the energy storage battery and converter are core links with high value.
At present, the global energy storage market is growing rapidly, and user-side energy storage is one of the important driving forces. According to the data of Frost & Sullivan, in 2021, the new installed capacity of global energy storage systems reached 25.2 GWh, with a year-on-year increase of 133.3%, with the installed capacity on the power generation side, power grid side and user side being 14.4, 2.7 and 8.1 GWh respectively, which shows rapid growth in the household energy storage market, especially in Europe and the United States.
China’s energy storage market is developing rapidly too with the support of national policies. Take Shenzhen as an example. Shenzhen plans to promote the application of distributed photovoltaic industry and industrial innovation, and explore the “double-carbon” power generation mode featuring “peak carbon dioxide emissions and carbon neutrality” in megacities. Specifically, Shenzhen vigorously promotes Building Integrated Photovoltaics (BIPV) and strives to increase the installed photovoltaic capacity by 1.5 million kilowatts, which is expected to reach 5 million kilowatts in 2025. The development of the global energy storage market in Shenzhen is extremely fast. If the practice of Shenzhen is promoted in other cities in China, huge market and development opportunities will be produced.
Photovoltaic/solar energy storage system applied to residential buildings
The photovoltaic/solar energy storage system applied to residential buildings is crucial to the further development of renewable energy and distributed energy generation. Easy-to-use products must be provided to design an efficient power conversion and battery management system, for which system cost and performance optimization are key driving factors, and fast appearance on the market and reliable delivery performance are key requirements.
Take a 10 kw solar energy storage system as an example. This 10 kw DC/AC three-phase photovoltaic inverter introduced by Arrow Electronics has a battery pack and a two-way charging system, and is mainly composed of four blocks, that is, a three-phase T-type DC-AC inverter block, a maximum power point tracking (MPPT) booster block, a bidirectional battery charging system block, and a human-machine interface (HMI) block, which can speed up product development and design for customers.
The topology of the three-phase T-type DC-AC inverter block is a 10-15 kw three-stage T-type inverter, using a SiC MOSFET supporting the 1200 V, 75 mΩ and TO247-4 package, and a SiC MOSFET supporting the 650 V, 45 A and TO247-4 package, and also equipped with the NCV1117ST and CS51414 DC regulators by onsemi, the NCV7357D CAN transceiver by onsemi and the NCS20061SN2T1G amplifier by onsemi.
The main devices of the MPPT booster block include the TMS320C28379 MCU by TI, a SiC MOSFET supporting the 1200 V, 75 mΩ and TO247-4 package, and a SiC diode supporting the 1200 V, 20 A and TO247-3 package, as well as the NCS20061SN2T1G amplifier and the NCV1117ST33T3G and NCV1117ST50T3G DC regulators by onsemi.
The topology of the bidirectional battery charging system is a 10 kw CLLLC bidirectional DCDC power converter, which adopts a primary SiC MOSFET supporting the 1200 V, 32 mΩ and TO247-4 package, and a secondary Si MOSFET supporting the 650 V, 15 mΩ and TO247-4 package, and is also equipped with an isolated SiC gate driver, an amplifier and a DC regulator by onsemi, and an MCU by TI.
The HMI block supports WiFi, Ethernet, RS485, CAN and other interfaces, is matched with an isolated auxiliary power daughter board, and supports a Vin of 900-1000 V DC Link Bus input and a Vout of 12 V/4A isolated DC output. The main devices adopted include the onsemi UC2844BD1R2G PWM controller, the onsemi 1700 V high-voltage SiC MOSFET, the onsemi FDMS86101DC low-voltage power MOSFET, the onsemi NCP4306DADZZ synchronous controller, the onsemi NCP431BCSNT1G reference voltage, the onsemi FOD817A optocoupler, the onsemi BCP56T1G power transistor, and many diodes and Zener diodes by onsemi.
High-efficiency bidirectional power converter
Arrow Electronics also introduced a bidirectional power converter for energy storage PFC, which is a reference design of bidirectional power converters for energy storage PFC. It consists of a totem pole PFC topology, and uses a SiC MOSFET to operate at high switching frequency to achieve high efficiency and reduce the size and weight.
The maximum charging power of the bidirectional power converter in the charging mode is 6.6 kw, the rated input voltage is 200 Vac to 265 Vac 50 Hz, the rated output voltage is 380 Vdc to 580 Vdc, and the efficiency can exceed 98%. In the inversion mode, the maximum inverter power is 6.6 kw, the inverter rated input voltage is 550 Vdc, and the inverter rated output voltage is 220 Vac 50 Hz, and the efficiency also exceeds 98%.
This bidirectional power converter for energy storage PFC can be used in high-power charging systems, such as UPS, solar energy systems, etc. This evaluation board can help users speed up the design of a SiC MOSFET system and significantly shortens the product development cycle.
Conclusion
Energy storage systems can improve the utilization efficiency of energy, and can be used in all links of a power system, including the power generation side, the power grid side and the user side, among which the market development potential of the user side is the greatest. This article introduced the energy storage solution developed by Arrow Electronics, which will greatly speed up the development of the energy storage system. To learn more about this energy storage system, please contact Arrow Electronics.