The MPPT (Maximum Power Point Tracking) technology of solar inverters is a technique that enables solar panels to always operate near the maximum power point. The following provides a detailed explanation of its principles, implementation methods, advantages, and challenges:
Working principle
The output characteristics of solar cells are affected by factors such as light intensity and temperature. Under different working conditions, solar cells have a corresponding maximum power output point. MPPT technology monitors the output voltage and current of solar panels in real time, calculates their output power, and adjusts the working state of the inverter according to the algorithm, so that the working point of the solar panel continuously approaches the maximum power point, thereby achieving the maximum power output of the solar panel under various lighting and temperature conditions.
Implementation method
Common algorithms
Disturbance observation method (P&O): By periodically perturbing the operating point of the solar panel and comparing the power changes before and after the disturbance, it is determined whether the current operating point is close to the maximum power point. If the power increases, continue to disturb in that direction; If the power decreases, it will be disturbed in the opposite direction. This method is simple and easy to implement, but tracking errors may occur when the light intensity and temperature change rapidly, and even cause the operating point to oscillate near the maximum power point, affecting tracking efficiency.
Conductivity incremental method (INC): Based on the power voltage characteristic curve of solar cells, the relative position between the operating point and the maximum power point is determined by comparing the increment of conductivity with the increment of current, and then adjusting the operating point. This method has high tracking accuracy, can quickly track the maximum power point under changes in lighting and temperature, and is not prone to oscillation. However, the algorithm is relatively complex and requires high hardware requirements.
Hardware circuit design: Implementing MPPT technology requires appropriate hardware circuit support. Usually, dedicated MPPT controllers or digital signal processors (DSPs) are used in solar inverters to execute algorithms. The hardware circuit also includes high-precision voltage and current sensors for real-time acquisition of output voltage and current signals of solar panels, as well as power switching devices for adjusting the operating point of solar panels.
advantage
Improving power generation efficiency: Effectively improving the overall efficiency of solar power generation systems, with the same solar panel configuration, the power generation can be increased by 10% -30%, depending on lighting conditions and system performance.
Cost reduction: By fully utilizing the power generation capacity of solar panels, the number of solar panels used can be reduced while meeting the same electricity demand, thereby reducing the initial investment cost of the system. At the same time, due to the increase in power generation, the cost per unit of electricity has also been reduced, improving the economy of solar power generation.
Challenges and Countermeasures
Rapidly changing environmental conditions: In practical applications, light intensity and temperature may change rapidly, which places high demands on the tracking speed and accuracy of MPPT technology. To address this challenge, researchers continuously improve algorithms to enhance their response speed and robustness, such as using adaptive algorithms to automatically adjust tracking strategies based on the speed of environmental changes.
Partial occlusion problem: When the solar panel is partially occluded, its output characteristics will undergo complex changes, which may result in multiple local maximum power points, leading to misjudgment by the MPPT algorithm. One solution is to use an MPPT algorithm with local occlusion detection and processing capabilities, which can identify and avoid local maximum power points, and track to the global maximum power point. In addition, optimizing the layout of solar panels and adopting intelligent bypass diodes can also help alleviate the impact of partial obstruction.
