Solar Module Decoupling Device for Fire Safety
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Solution Overview
Problem
Photovoltaic systems mounted on roofs pose a fire hazard due to their inability to be turned off, increasing the risk for firefighters, and existing solutions to mitigate this hazard are costly and detrimental to system reliability.
Innovation Solution
A solar system configuration that includes a device to electrically decouple solar modules from the system using a low-cost, low-power transformer and thermal switches or power transistors, which provide a closed circuit when an AC signal is present and an open circuit when it is not, allowing for safe disconnection of modules during emergencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PV systems are mounted on roofs to generate renewable energy, then energy production is improved, but fire hazard increases due to inability to turn off the power source
Solution Approach 1:
The PV system is segmented into individually controllable modules, each with its own decoupling device. This allows selective disconnection of specific modules from the string circuit without affecting other modules, enabling targeted shutdown during fire emergencies while maintaining power generation from unaffected modules.
Solution Approach 2:
A decoupling device is introduced as an intermediary component between the PV modules and the string circuit. This device includes a switch element controlled by a control circuit that responds to emergency signals, mediating the connection/disconnection to eliminate direct electrical hazard while allowing normal operation under normal conditions.
2Object-affected harmful factors
If existing solutions are implemented to reduce electrical hazard during fires, then fire safety is improved, but system cost increases significantly
Solution Approach 1:
The decoupling device utilizes the existing AC mains power infrastructure to provide control signals for shutdown. The control circuit detects the absence of AC power (indicating firefighter action) and automatically triggers the switch element to open, eliminating the need for separate emergency power sources or complex control systems.
Solution Approach 2:
The decoupling device serves multiple functions: normal operation switching, emergency shutdown, and system protection. By designing a single device that handles all these functions, the patent avoids the cost penalty of having separate dedicated systems for each function.
3Object-affected harmful factors
If existing solutions are implemented to reduce electrical hazard during fires, then fire safety is improved, but system reliability is reduced
Solution Approach 1:
The system incorporates a bypass diode in parallel with the switch element that provides a predetermined alternative current path. This cushioning measure ensures that if the switch element fails or malfunctions, current can still flow through the bypass path, maintaining system operation and preventing complete system failure.
Solution Approach 2:
The control circuit monitors electrical parameters such as AC power presence and voltage levels to determine when shutdown is required. By continuously monitoring these parameters and responding to changes, the system maintains reliability through adaptive control rather than fixed, potentially failure-prone mechanical switches.
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 reduces electrical hazards during fires by allowing individual solar modules to be turned off without compromising the reliability or increasing the cost of the PV system, ensuring safer firefighting conditions while maintaining system functionality.
Implementation Method 1
the switch is a thermal switch and the thermally conductive material is thermally coupled to the thermal switch
Implementation Method 2
the switch is a power transistor and the thermally conductive material is coupled to the power transistor
Data Source
AI summary
Devices and methods for electrically decoupling a solar module from a solar system are described. In one embodiment, a solar system includes a string of a plurality of solar modules coupled with an inverter through a DC power line. An AC input is coupled with the DC power line. A device is also included and is configured to provide a closed circuit for one of the plurality of solar modules if an AC signal voltage from the AC input is present on the DC power line, and is configured to provide an open circuit for the one of the plurality of solar modules if no AC signal voltage from the AC input is present on the DC power line.