The application of solar power generation and energy storage technology not only serves as an important supplement to current human energy utilization, but also has the potential to become the main source of energy for future human activities. This article focuses on the research of household solar off grid inverter energy storage systems, and the main research is as follows:
(1) A design method for MPPT step-down solar charger was proposed, and the working mode, circuit design, charging control strategy, and battery management of the charger were studied during solar charging. When the charging current is greater than 10% of the rated charging current, the MPPT efficiency of the charger will reach over 99%, and the maximum conversion efficiency will reach 98.5%, which can meet the needs of solar energy storage charging.
(2) Through the study of the functional parts of battery discharge and mains charging in household solar off grid inverter energy storage systems, a DC-DC bidirectional conversion circuit was designed to meet the requirements of both boosting the battery in battery discharge mode and lowering the BUS voltage in mains charging mode.
(3) A design method for a full bridge AC-DC bidirectional converter has been proposed. The bidirectional converter meets the requirements of a household solar off grid inverter energy storage system. On the one hand, it needs to invert the high-voltage DC bus into AC to provide for household loads, and on the other hand, it needs to rectify the AC mains power to the high-voltage DC bus to provide bidirectional applications for subsequent charging and energy storage.
(4) Establish a complete system architecture for a 5 kW household solar off grid inverter energy storage integrated machine by integrating three major functional modules. The MPPT tracking efficiency and inverter conversion efficiency of the all-in-one machine were tested, proving the effectiveness and feasibility of the design method.
(5) A household solar off grid inverter energy storage system was designed using the PVsyst simulation design software, with a 5 kW household solar off grid inverter energy storage integrated machine as the core, and the practicality of the design was verified.
During the research process, it was found that the utilization and management of solar energy storage is still a relatively cutting-edge project. By combining power electronics technology, material chemistry technology, and control theory, the research prospects in this field are very broad. Although these technologies have been widely applied in the field of photovoltaic power generation and energy storage, there are still many technical problems that need to be solved, especially in energy network management, lithium battery charging and discharging management, and improving the overall efficiency of inverters, which require further research, including:
(1) The hardware structure of solar MPPT charging has been studied, and the efficiency of MPPT has only been verified using a PV simulator. Further stability and accuracy need to be tested in actual operation.
(2) Due to the significant influence of sunlight environmental factors on the stability of solar power generation, the solar charging controller needs to adapt to the application of solar power generation environment. Therefore, it is necessary to study the control strategy of solar charging controller and the charging and discharging management strategy of battery pack in the solar power generation energy storage system.
(3) This is a study on a single 5 kW household solar off grid inverter energy storage system. Of course, in practical applications of inverters, running two or more low-power inverters in parallel to obtain higher power is also of practical value. In the parallel operation of multiple inverters, higher technical requirements have also been put forward for the control strategy of inverters, which can be considered for future research.
In the future, based on solar photovoltaic power generation, technologies such as photovoltaic+energy storage, independent off grid power supply, integration of off grid and grid, and distributed energy storage for peak shaving and valley filling will gradually emerge. There is no doubt that the application prospects of solar power generation and energy storage technology will be very significant.