Rapid Shutdown Device for Photovoltaic Safety
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Solution Overview
Problem
Conventional photovoltaic systems with serially-connected elements pose safety risks during natural disasters due to high internal voltages, which conventional rapid shutdown devices do not adequately address, threatening the safety of personnel like firefighters.
Innovation Solution
A rapid shutdown device with a switching circuit, control circuit, communication circuit, and auxiliary power circuit is integrated into the photovoltaic system, allowing for controlled disconnection of photovoltaic elements from the system using command signals from the inverter, thereby reducing voltage hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple photovoltaic elements are serially connected to generate high voltage, then power generation efficiency is improved, but safety risk increases due to high internal voltage during emergencies
Solution Approach 1:
The rapid shutdown device divides the high-voltage photovoltaic system into multiple isolated segments using switching circuits. When emergency shutdown is triggered, the device isolates individual photovoltaic element groups from each other, transforming one high-voltage dangerous segment into multiple low-voltage safe segments, thereby eliminating electric shock hazards while preserving the power generation capability of the system
2Reliability
If a rapid shutdown device is installed to isolate photovoltaic elements during malfunction, then safety is improved, but internal voltage of photovoltaic elements remains high
Solution Approach 1:
The switching circuit implements multi-point isolation within the photovoltaic string, creating electrically independent segments. By opening switches at multiple locations simultaneously, the device ensures that no single photovoltaic element or small group maintains high voltage potential, as all elements are isolated from the high-voltage bus and from each other
Solution Approach 2:
The rapid shutdown device acts as an intermediary between the photovoltaic elements and the inverter, and also as an intermediary that creates isolation zones between different photovoltaic element groups. This intermediary function allows the system to maintain safety by preventing direct electrical connection between high-voltage sources and personnel access points
Data Source
AI summary
A rapid shutdown device and a photovoltaic system are provided. The photovoltaic system includes an inverter and multiple serially-connected photovoltaic elements. The rapid shutdown device includes a switching circuit, a control circuit, a communication circuit and an auxiliary power circuit. The switching circuit includes a first switch and a second switch. A first terminal of the first switch is electrically connected with the positive terminal of a first photovoltaic element. A second terminal of the first switch is electrically connected with the negative terminal of a second photovoltaic element. A first terminal of the second switch is electrically connected with the negative terminal of the first photovoltaic element. The communication circuit receives a command signal from the inverter and transmits it to the control circuit. The control circuit controls the first switch and the second switch to turn on or turn off according to the command signal.