Solar Panel Junction Box Overvoltage Protection Circuit
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Solution Overview
Problem
Conventional solar panels face issues with reduced output and potential damage due to varying irradiation intensities and voltage peaks, which can lead to operational safety and lifespan reduction.
Innovation Solution
A junction box design with at least three electrical contact devices, two bypass diodes, and an overvoltage protection diode, where the overvoltage protection diode is connected in parallel with the bypass diodes to protect against overvoltages and voltage spikes, ensuring safe operation and extended lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass diodes are used to protect against partial shading, then the current flow is maintained and damage is prevented, but the response time is too slow to protect against voltage peaks from thunderstorms or line inductances
Solution Approach 1:
A capacitor is introduced as an intermediary component between the solar cell and bypass diode. The capacitor responds instantaneously to voltage peaks by absorbing excess voltage, buying time for the bypass diode to activate. This mediator resolves the speed mismatch between the fast-acting voltage peaks and the slower bypass diode response.
Solution Approach 2:
The capacitor is pre-charged during normal operation and stands ready to immediately counteract voltage peaks before they can damage the bypass diode. This preliminary energy storage prepares the system in advance for potential overvoltage events, enabling faster protection without modifying the bypass diode itself.
2Reliability
If multiple bypass diodes are added to protect against partial shading of multiple solar cell groups, then the reliability under shading conditions improves, but the device complexity and cost increase
Solution Approach 1:
The capacitor serves multiple functions: it protects against voltage peaks from thunderstorms, protects against voltage spikes from line inductances, and works in conjunction with bypass diodes to protect against partial shading. This single component provides universal protection across multiple failure modes, reducing the need for additional specialized components.
Solution Approach 2:
The capacitor combines the protection functions of multiple bypass diodes into a single protective mechanism. Instead of requiring separate bypass diodes for each solar cell group, the capacitor provides centralized overvoltage protection that works across the entire array, simplifying the overall device architecture.
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 prevents damage from voltage peaks and ensures continuous operation by diverting current through the bypass diodes during overvoltages, maintaining the solar panel's performance and reliability.
Implementation Method 1
at least one overvoltage protection diode, wherein the first of the at least two bypass diodes electrically connects the first contact device to the second contact device and the second of the at least two bypass diodes electrically connects the second contact device to the third contact device, and wherein the at least one overvoltage protection diode is connected in parallel with at least one of the bypass diodes
Data Source
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AI summary
The socket (7) has electrical contact devices (13a-13d) i.e. metal sheet punching elements, contacted with electrical wires (5a-5d) i.e. conductor bands, of a solar module (3), where the socket is casted with synthetic resin. A bypass-diode (25a) electrically connects one of the contact devices (13a) with another contact device (13b). Another bypass-diode (25b) electrically contacts the latter contact device (13b) with the third contact device (13c). Over voltage-protection diodes (27) i.e. surface mounted device-components, are connected parallel to the bypass-diodes. The over voltage-protection diodes are designed as suppressor diodes, bipolar-suppressor diodes, zener diodes, schottky-diodes and varistors. An independent claim is also included for a method for manufacturing the connection socket.