Photovoltaic String Disconnection Apparatus with Energy Harvesting
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Solution Overview
Problem
Existing solar installations with string inverters require additional lines for signal transmission and power supply, and integrating protective circuits into existing installations is cumbersome, especially due to space constraints and the need for multiple connection boxes.
Innovation Solution
A disconnection apparatus for photovoltaic strings that integrates a circuit breaker, band-stop filter, and supply circuit in series, with a bandpass filter and reverse current diode to enable energy autonomy and efficient power supply, reducing the need for additional lines and simplifying integration into existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective circuits are integrated into each solar module connection box, then safety compliance is achieved, but installation complexity and space requirements increase
Solution Approach 1:
The protective function is segmented from individual module connection boxes and consolidated into a single disconnection apparatus positioned between the string combiner and inverter. This segmentation approach maintains safety compliance while reducing the number of protective circuits from multiple modules to a single centralized unit, thereby simplifying installation and reducing space requirements.
Solution Approach 2:
The disconnection apparatus acts as an intermediary component between the photovoltaic string combiner and the inverter DC input. It provides the necessary protective disconnection function without requiring integration into each individual solar module's connection box, thus avoiding the space constraints and installation complexity associated with modular integration while ensuring safety standard compliance.
2Ease of operation
If additional lines are added for signal transmission and power supply, then protective circuit operation is enabled, but installation complexity and wiring requirements increase
Solution Approach 1:
The disconnection apparatus is designed to operate using the existing DC string current that flows through the photovoltaic string. The apparatus performs multiple functions including power reception, control signal processing, and protective disconnection, all without requiring additional dedicated power supply lines or signal transmission wires. This multi-functional design eliminates the need for extra wiring while ensuring reliable protective circuit operation.
Solution Approach 2:
The disconnection apparatus utilizes the existing DC current flowing through the photovoltaic string to power its operation and process control signals. By harvesting energy and signals from the existing string current, the apparatus makes itself self-sufficient without requiring external power supply lines or additional signal transmission infrastructure, thereby reducing wiring complexity while maintaining operational capability.
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 allows for reliable energy supply to the disconnection apparatus and other components, ensuring safe operation and easy startup of solar installations without the need for additional lines, while minimizing power draw from control signals and reducing installation complexity.
Implementation Method 1
A bandpass filter for coupling out a high-frequency control signal from the electrical connection bridges the circuit breaker and the band-stop filter in parallel
Implementation Method 2
a diode that is oppositely polarized relative to an operating current flow direction, the diode being referred to hereinafter as reverse current diode, is connected in parallel with the circuit breaker. In this configuration, a reverse current can flow through the string even with the circuit breaker open
Implementation Method 3
the electrical power for supplying the disconnection apparatus and, if appropriate, the further electrical components is substantially drawn from a direct current flowing between the first and second terminals
Data Source
AI summary
A description is given of an apparatus for disconnecting an electrical connection between solar modules of a photovoltaic string, the apparatus including a first and a second terminal for a respectively assigned solar module of the photovoltaic string, also a circuit breaker, a band-stop filter and a supply circuit for supplying energy to the apparatus, which are arranged in a series circuit with respect to one another between the first and second terminals. A bandpass filter for coupling out a high-frequency control signal from the electrical connection bridges the circuit breaker and the band-stop filter in parallel. In this case, a reverse current diode that is oppositely polarized relative to an operating current flow direction is connected in parallel with the circuit breaker or the partial series circuit comprising the circuit breaker and the band-stop filter.