Photovoltaic Grounding Switches for Residual Voltage Dissipation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Photovoltaic arrays generate high DC voltages that persist even after external power and inverter shutdown, posing a safety risk during emergencies like fires, as the DC cabling remains at operating voltage, necessitating a method to reduce electrical potential for safe access.
Innovation Solution
A photovoltaic power system with improved grounding is implemented, utilizing multiple grounding points connected via switches between the photovoltaic array, combiner box, and DC to AC inverter, allowing for safe reduction of DC voltage by grounding the positive and negative conductors, which can be manually, remotely, or automatically activated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC cabling is physically protected in metal conduit with fused thermal protection, then safety and reliability are improved, but the cabling remains at operating voltage even after power shutdown, creating a new safety hazard during emergencies
Solution Approach 1:
The patent extracts the grounding function from the standard protective measures and adds it as a separate, controllable system. Switches are installed to disconnect the DC cabling from the photovoltaic array, allowing the cabling to be grounded independently of the array's operational state. This extraction enables the cabling to be safely discharged without compromising the metal conduit protection.
Solution Approach 2:
The patent implements preliminary grounding action by providing a mechanism to ground the DC cabling before emergency personnel need to access the building. The switches can be activated to connect the cabling to ground, dissipating residual voltage in advance of any emergency response activities, thus preventing the harmful effect before it can cause harm.
2Object-affected harmful factors
If switches are added to enable grounding of DC conductors, then safety during emergencies is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing grounding switches only at specific locations where DC cabling enters buildings or structures, rather than throughout the entire photovoltaic system. This localized approach provides safety where it is most needed during emergencies while minimizing the overall increase in system complexity.
Solution Approach 2:
The grounding switches serve multiple functions: they provide emergency safety grounding, enable controlled discharge of residual voltage, and can potentially be integrated with existing system monitoring and control infrastructure. This multi-functionality justifies the added complexity by delivering multiple safety and operational benefits from a single component addition.
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 system effectively reduces residual voltage on DC cabling, enhancing safety during emergencies by enabling safe access to the building by grounding the conductors at multiple points, ensuring electrical safety and compliance with industry standards.
Implementation Method 1
a positive-conductor ground electrically connected by a switch to the positive conductor and a negative-conductor ground electrically connected by a switch to the negative conductor
Data Source
AI summary
Embodiments disclosed include photovoltaic power systems and methods for manufacturing the same. A photovoltaic power system can include a photovoltaic array, a DC to AC inverter, a positive conductor electrically connecting a positive inverter terminal of the DC to AC inverter to the positive array terminal and a negative conductor electrically connecting a negative inverter terminal of the DC to AC inverter to the negative array terminal, a positive-conductor ground electrically connected by a switch to the positive conductor, and a negative-conductor ground electrically connected by a switch to the negative conductor.