Solar String Shut-Off Layout for Low-Power Rapid Shutdown
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Solution Overview
Problem
The existing solar power generation systems face increased installation costs and operational instability due to the requirement for rapid shutdown functions, particularly affecting firefighters' safety, as the shut-off devices for solar cell modules can lead to unstable power supply and repeated switching between ON and OFF states when power generation is low or unstable.
Innovation Solution
A solar power generation system is designed with a master-slave configuration of shut-off devices, where the first shut-off device cuts off connections to the inverter when power falls below a threshold, allowing the second shut-off device to operate independently and reducing installation costs by simplifying its configuration, and using semiconductor switching devices like MOSFET or IGBT to maintain stability even with low power, and communication via a different system than power line communication to prevent noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shut-off device is installed for each solar cell module to improve firefighter safety, then safety is improved, but installation cost increases
Solution Approach 1:
The patent combines multiple solar cell modules into a single string with one shut-off device, merging the protection function across multiple modules to reduce the total number of shut-off devices needed while maintaining safety standards
Solution Approach 2:
The shut-off device is designed to control multiple solar cell modules simultaneously, making a single device serve multiple protection zones and reducing overall system complexity
2Loss of time
If the switching element is driven by power from solar cell modules, then the system uses self-generated power, but operational stability deteriorates when power generation drops
Solution Approach 1:
The system stores power in advance during periods of high generation to ensure sufficient power is available for the switching element during low generation periods, preventing operational instability
Solution Approach 2:
The power storage device acts as a cushion, absorbing power fluctuations and ensuring stable power supply to the switching element even when solar cell output drops, preventing repeated ON/OFF switching
3Device complexity
If power line communication is used for control signals, then communication is simplified, but noise interference increases affecting stability
Solution Approach 1:
The patent introduces a dedicated communication line as an intermediary between the inverter and shut-off device, separating control signals from power lines to eliminate electromagnetic interference while maintaining communication functionality
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
This configuration decreases installation costs and improves the stability of the solar power generation system by ensuring the shut-off devices can maintain operation even with low or unstable power supply, enhancing safety and efficiency.
Implementation Method 1
The inverter is connected to the string for converting DC power output from the solar cell modules to AC power
Implementation Method 2
a plurality of solar cell modules connected in series
Data Source
AI summary
A solar power generation system includes a string, an inverter, and first and second shut-off devices. The string includes a plurality of solar cell module groups. The first shut-off device cuts off the connections between the plurality of solar cell module groups of a first electric path in response to a first control signal. The second shut-off device cuts off the connections between the plurality of solar cell module groups in a second electric path in response to a second control signal output by a different communication system. The first shut-off device includes a first open-close unit, a first semiconductor switching device connected in series to the first open-close unit and a power supply unit configured to generate power to drive the first open-close unit. The first semiconductor switching device enters an OFF state if the amount of generated power is smaller than a predetermined threshold value.