In the current era of rapid development of the photovoltaic industry, the "photovoltaic + energy storage" combination model has gradually become a necessity. During the day when there is sufficient sunlight, the photovoltaic system often generates more electricity than the demand, resulting in wasted energy; while during the peak hours of electricity consumption in the morning and evening, the photovoltaic system is unable to supply power and can only rely on the power grid. The addition of an energy storage system perfectly solves this "supply-demand mismatch" problem. Through "peak shaving and valley filling", it not only improves the utilization rate of electricity but also reduces electricity costs, and even provides emergency power supply in case of power grid failure. However, the integration of photovoltaic and energy storage is not a simple combination; it involves many technical details. Today, let's talk about the four core design points of the photovoltaic + energy storage system.
Design Point 1: Bidirectional power conversion to achieve efficient energy flow. The power conversion in traditional photovoltaic systems is unidirectional, that is, the DC electricity generated by the photovoltaic module is converted into AC electricity through an inverter for use by the load or fed into the power grid. After adding an energy storage system, it is necessary to achieve energy flow in two directions: "photovoltaic charging to energy storage" and "energy storage discharging to load/power grid". This requires the use of a bidirectional power conversion architecture. Compared with the traditional "two unidirectional converters" solution, the bidirectional power converter can combine the charging and discharging paths into one, reducing the number of components and system costs, while improving energy conversion efficiency. Currently, the industry mostly adopts a digital control scheme based on real-time microcontrollers (MCU), using complex pulse width modulation (PWM) technology to achieve safe and efficient energy transmission between the power grid, photovoltaic array, and energy storage battery. 
Design Point 2: Selection of High-Voltage Batteries and Adaptation for System Power Upgrade. As the power of photovoltaic systems continues to increase, the voltage level of energy storage batteries is also upgrading. Previously, photovoltaic energy storage systems mostly used 48V battery packs, but now 400V battery packs have gradually become the mainstream, especially in industrial and large-scale photovoltaic power station scenarios. High-voltage battery packs have higher energy storage density and transmission efficiency, but they also place higher demands on power conversion. To match the 400V battery packs, low-loss and high-efficiency power switching devices are required, such as wide-bandgap semiconductor devices based on silicon carbide (SiC) and gallium nitride (GaN). These materials can effectively reduce switching losses and improve the power density of the converter, ensuring the system operates stably at high voltages. Additionally, 400V battery packs from retired electric vehicles are also gradually being applied to photovoltaic energy storage systems, achieving resource recycling and further reducing costs. 
Design Point 3: Thermal Optimization Design, Balancing Safety and Aesthetics. Today's energy storage systems not only need to be practical but also need to consider appearance, especially for wall-mounted energy storage devices in residential and industrial/commercial settings, where there are high requirements for volume and aesthetics. This requires the adoption of thermal optimization solutions in the design. Through a distributed power supply architecture, heat is dispersed throughout the system, reducing the risk of local overheating and achieving natural convection cooling. This avoids the use of large fans for heat dissipation, thereby reducing energy consumption and making the system more streamlined and aesthetically pleasing. In terms of component layout, it is necessary to reasonably plan power devices and heat dissipation channels to ensure that the system can operate stably in complex environments such as high temperatures and humidity. 
Design Point 4: Precise Current and Voltage Sensing to Ensure System Stability and Controllability. During the operation of the photovoltaic + energy storage system, there are frequent fluctuations in current and voltage, especially in scenarios with high switching frequencies. Precise current and voltage sensing is crucial as it can provide real-time feedback on the system's operating status, offering accurate data for the MCU's control decisions and preventing equipment damage due to overcurrent or overvoltage. In the design, high-precision sensing components need to be selected, and the layout of the sensing circuit should be optimized to reduce the impact of electromagnetic interference on the sensing accuracy. Additionally, a comprehensive protection mechanism should be coordinated to respond quickly when there are abnormalities in current or voltage, cutting off the faulty circuit to ensure system safety. 
In addition to the above four core points, the design of the photovoltaic + energy storage system also needs to take into account resource and environmental factors (such as local sunlight conditions, extreme weather), economic costs (equipment procurement, installation and maintenance expenses), and intelligent scalability (real-time monitoring, remote management), etc. Nowadays, with the continuous maturation of technology, the application scenarios of "photovoltaic + energy storage" are becoming increasingly widespread. From household rooftops to large power stations, from industrial and commercial parks to remote areas without electricity, its presence can be seen everywhere. In the future, with the advancement of battery technology and the reduction of costs, "photovoltaic + energy storage" will become the mainstream mode of new energy power supply, providing important support for achieving the "dual carbon" goal.