Remote Disconnect Device for PV Array Safety
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Solution Overview
Problem
Fire departments face safety risks and increased response times when dealing with fires in buildings equipped with photovoltaic (PV) power systems, as rooftop-mounted disconnect switches are aesthetically unpleasing, pose safety risks, and are susceptible to corrosion, and existing solutions require firefighters to manually operate switches on the roof, while PV panels remain energized during daylight.
Innovation Solution
A remote disconnect device is positioned near the PV array, typically in a protected space beneath the roof, which senses the removal of power from the electrical interface and electrically disconnects the PV array from the inverter, using a control mechanism to create an open circuit and ensure safe de-energization of electrical wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rooftop-mounted disconnect switch is used, then firefighters can manually de-energize PV panels, but the device is exposed to environmental corrosion and requires firefighters to access the roof (increasing response time and safety risks)
Solution Approach 1:
The patent introduces an intermediary remote disconnect device that is electrically connected to the PV system but physically located in a protected environment (such as a utility room or equipment closet) rather than on the rooftop. This intermediary device allows firefighters to de-energize the PV system without exposing themselves to environmental corrosion on the roof or safety risks of roof access, while still achieving the same functional result of disconnecting the PV array from the inverter.
2Reliability
If an external disconnect switch on the roof is installed, then all PV circuits can be deactivated, but the device is aesthetically unpleasing and susceptible to corrosion
Solution Approach 1:
The remote disconnect device serves as an intermediary that relocates the disconnect functionality from the aesthetically sensitive rooftop area to a more acceptable location such as a utility room, equipment closet, or other protected space within or near the building. This maintains the full deactivation capability while improving aesthetic appearance and environmental durability.
Solution Approach 2:
The patent segments the PV system control into two separate locations: the PV array remains on the rooftop while the disconnect device is placed in a protected location. This segmentation allows the aesthetic and environmental concerns of the rooftop to be separated from the functional requirement of circuit deactivation.
3Reliability
If firefighters manually operate rooftop disconnect switches, then PV panels can be de-energized, but response time is increased and safety risks are elevated
Solution Approach 1:
By providing an intermediary remote disconnect device in a readily accessible protected location, the patent eliminates the need for firefighters to travel to the rooftop and perform manual disconnection. The device can be operated from ground level or from a safe location within the building, significantly reducing response time and eliminating the safety risks associated with roof access during emergency situations.
Data Source
AI summary
A PV installation comprises a PV array, an electrical interface connecting a utility power source to an electrical load, and a DC to AC inverter. A first set of wiring electrically connects the PV array to the inverter through a disconnect device and a second set of wiring electrically connects the inverter to the electrical interface. A control mechanism connects the disconnect device to the electrical interface so that when power from the electrical interface is removed, the PV array is electrically disconnected from the inverter. The disconnect device may be a remote disconnect device located at a position at or near the PV array, such as in the space beneath a roof supporting the PV array. A method electrically disconnects a PV array from electrical wiring at a site.