PV Panel Wireline Keep-Alive Control for Rapid Shutdown
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Solution Overview
Problem
There is a need to address safety issues in the proliferation of photovoltaic (PV) systems, particularly in ensuring rapid shutdown and controlled reactivation of solar panel connectivity to the power grid to protect emergency personnel from electric shock and energy hazards, as mandated by safety standards like the National Electrical Code (NEC).
Innovation Solution
A photovoltaic system that includes an inverter, solar panels, electrical wiring, and a transmitter that uses a multibit wireline messaging protocol to selectively connect or disconnect solar panels from the grid through a safety actuator, employing Keep-Alive signals to maintain or disrupt power supply based on signal detection, ensuring compliance with safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solar panels are continuously connected to the power grid, then energy generation and supply efficiency is improved, but safety hazards from electric shock and energy exposure to emergency personnel worsen
Solution Approach 1:
The system performs preliminary action by implementing rapid shutdown capability that can disconnect solar panels from the grid within 30 seconds of receiving an actuator signal. This preliminary safety measure ensures that before emergency personnel arrive at the scene, the system has already reduced voltage to safe levels (not more than 30 VDC, or 15 VAC at 8 A), preventing electric shock hazards while maintaining normal operation during non-emergency conditions.
Solution Approach 2:
The patent introduces an intermediary control system consisting of a transmitter and receiver that communicate through the electrical wiring to control the disconnect device. This intermediary messaging protocol system acts as a mediator between the inverter and the disconnect mechanism, enabling rapid shutdown and controlled reactivation without direct human intervention at the panel level, thus resolving the conflict between continuous operation and safety.
2Object-affected harmful factors
If rapid shutdown capability is implemented, then safety for emergency personnel is improved, but system complexity and control requirements worsen
Solution Approach 1:
The electrical wiring in the solar panel system serves multiple functions: it acts as both the power transmission medium and the communication channel for the messaging protocol. The existing wiring infrastructure is utilized for dual purposes - carrying both power signals and control messages, thereby implementing rapid shutdown capability without adding separate complex control wiring or communication systems.
Solution Approach 2:
The system implements self-service through automated shutdown and reactivation control. The receiver detects actuator signals and automatically triggers the disconnect device to shut down the solar panels. Similarly, the transmitter can automatically reactivate the system by sending reactivation messages through the wiring, eliminating the need for manual intervention and reducing operational complexity.
3Reliability
If controlled reactivation is implemented, then safety compliance with NEC requirements is improved, but response time and operational delays worsen
Solution Approach 1:
The system implements feedback control where the receiver continuously monitors for actuator signals on the electrical wiring. When a shutdown signal is detected, the disconnect device activates to reduce voltage. For reactivation, the transmitter monitors system conditions and automatically sends reactivation messages when safe to operate, creating a feedback loop that ensures safety compliance while minimizing reactivation delays through automated decision-making.
Data Source
AI summary
A photovoltaic system with an inverter, at least one solar panel for providing electrical power, and electrical wiring for coupling electrical power from the at least one solar panel to the inverter. Also included is a transmitter for transmitting a messaging protocol along the electrical wiring, where the protocol includes a multibit wireline signal. Also included is circuitry for selectively connecting the electrical power from the at least one solar panel along the electrical wiring to the inverter in response to the messaging protocol.