Inverter Ground Potential Adjustment for Solar PID Recovery
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Solution Overview
Problem
The increasing voltage in solar power systems leads to potential induced degradation (PID) due to leakage currents, causing performance degradation in solar cell modules, especially when humidity and temperature conditions are high, and existing solutions to recover degraded performance often complicate the power supply system and increase costs.
Innovation Solution
A power supply system incorporating an AC voltage measurement circuit that applies a predetermined voltage to solar cell modules at night via an inverter, using a circuit with resistors and diodes to adjust the potential, thereby recovering degraded performance while minimizing the number of components and maintaining system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate device is added to recover degraded performance of solar cell modules, then performance degradation due to PID can be suppressed, but the power supply system becomes larger and more complicated
Solution Approach 1:
The patent combines the PID recovery function with the existing inverter by integrating a ground potential adjustment circuit into the inverter's control unit. This allows the inverter to apply a predetermined voltage to adjust the ground potential of solar cell modules during nighttime recovery periods, eliminating the need for separate recovery devices and reducing system complexity while maintaining effective PID suppression
Solution Approach 2:
The inverter is designed to perform multiple functions: it not only converts DC power from solar cells to AC power for grid supply during daytime operation, but also adjusts the ground potential of solar cell modules during nighttime to suppress PID. This multi-functionality allows a single device to handle both power conversion and performance recovery tasks
2Power
If the voltage of solar power generation system is increased, then power generation efficiency is improved, but potential difference between cell and grounded frame increases causing leakage current and PID phenomenon
Solution Approach 1:
The patent applies a predetermined voltage to the solar cell modules during nighttime before PID degradation can progress further. This preliminary anti-action counteracts the harmful effects of high voltage operation by adjusting the ground potential to prevent ion migration and performance degradation that would otherwise occur during high-voltage daytime operation
3Productivity
If solar cell modules operate at high voltage during daytime, then power generation efficiency increases, but performance degradation occurs due to negative ground potential
Solution Approach 1:
The patent implements periodic action by operating the solar cell modules at high voltage during daytime for maximum power generation efficiency, then switching to ground potential adjustment mode during nighttime to recover and prevent PID degradation. This periodic alternation between power generation mode and recovery mode allows the system to maintain both high productivity during operation and high reliability over time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses performance degradation due to PID by setting the ground potential of solar cell modules to a positive value at night, preventing further degradation and simplifying the system without increasing costs.
Implementation Method 1
The cell 13 is an element having a semiconductor layer (power generation layer) that converts light energy into power using a photovoltaic effect
Data Source
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AI summary
A power supply system (100, 200, 300, 400, 500,), comprising: a solar cell (110); a non-isolated type DC/DC converter (120), boosting a DC voltage from the solar cell (110) input from an input end with a predetermined boosting ratio and outputting a DC voltage from an output end; and an inverter (31), converting the DC voltage output from an output end of the DC/DC converter (120) into an AC voltage, the power supply system (100, 200, 300, 400, 500,) being connected to an external power system for system interconnection, wherein the power supply system (100, 200, 300, 400, 500,) comprises a potential adjustment device (130, 131, 132, 133, 134, 135, 136, 137, 138) for applying a voltage of an external power system to the solar cell (110) via the inverter (31) to set a ground potential of a negative electrode of the solar cell (110) to positive when an output of the solar cell (110) is smaller than a predetermined value.