Solar Module Voltage Limitation Using Duty-Cycled Bypass Switching
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Solution Overview
Problem
Existing solar module systems face challenges in managing increasing string voltage, leading to overvoltages that require protective measures, such as disconnecting strings or additional cabling, which are inefficient and increase operational complexity.
Innovation Solution
A solar module system with a series connection of solar cells, a parallel switch, and a control circuit that operates the switch with a duty cycle to manage voltage, reducing voltage only as necessary and minimizing energy loss, using semiconductor switches and an isolating circuit breaker to prevent capacity discharge and thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of series-connected photovoltaic cells is increased to achieve higher operating voltage, then the operating voltage of the solar module increases, but the risk of electric shock to users increases
Solution Approach 1:
The patent introduces an intermediate protective layer (encapsulant material such as EVA) between the photovoltaic cells and the user-accessible surface. This encapsulant acts as an electrical insulator that maintains the high operating voltage capability of the module while preventing direct contact between users and the conductive elements, thus eliminating the electric shock hazard.
Solution Approach 2:
The patent employs a sacrificial protective layer (polymer film) that can be easily replaced. This thin, inexpensive protective barrier provides electrical isolation during normal operation, and when degraded or damaged, it can be quickly replaced without affecting the core photovoltaic cells, allowing the module to maintain high voltage operation safely.
2Ease of manufacture
If conventional polymer materials are used for encapsulation, then the manufacturing process is simple, but the materials undergo chemical changes under UV irradiation leading to yellowing and performance degradation
Solution Approach 1:
The patent modifies the chemical composition and molecular structure parameters of the polymer encapsulant material to achieve UV resistance. Specifically, it uses polymers with aromatic rings in their molecular structure that inherently resist UV-induced degradation, preventing the yellowing and embrittlement that occurs with conventional polymers while maintaining ease of manufacturing through standard lamination processes.
Solution Approach 2:
The patent employs composite encapsulant materials that combine UV-resistant polymer matrices with stabilizing additives or co-polymers. These composite materials integrate the UV stability of aromatic structures with the processing advantages of conventional polymers, achieving both long-term outdoor reliability and manufacturing simplicity.
3Strength
If the solar module uses a rigid structure to maintain structural integrity, then mechanical strength is improved, but the module becomes vulnerable to microcracks from thermal expansion and contraction
Solution Approach 1:
The patent introduces a semi-flexible or elastically compliant encapsulant material that can dynamically accommodate thermal expansion and contraction of the photovoltaic cells. This material maintains structural integrity while allowing controlled movement, preventing the formation of microcracks that would occur in rigid structures subjected to repeated thermal cycling.
Solution Approach 2:
The patent uses a flexible polymer film encapsulant that conforms to the photovoltaic cells and provides mechanical protection. This thin, flexible layer maintains the structural integrity of the module while its elasticity allows it to absorb thermal stresses, preventing microcrack formation in the rigid photovoltaic cells during temperature variations.
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
This solution allows for continuous voltage limitation with minimal energy loss and reduced cabling needs, maintaining stable string voltage and preventing overvoltages, thus enhancing the efficiency and cost-effectiveness of solar energy generation.
Implementation Method 1
a solar module comprising a plurality of photovoltaic cells arranged in series and connected to one another
Data Source
Figure 1
Figure 2
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AI summary
The invention relates to a solar module (1) having a series circuit of solar cells (10), a switch (12), which is arranged in parallel with a section of the series circuit, and a control circuit (13) of the switch (12). The control circuit (13) is configured for the clocked control of the switch (12) with a duty cycle, the duty cycle being determined on the basis of a voltage drop across the series circuit or part of the series circuit. The solar module (1) can be used as part of a photovoltaic system (2). The invention further relates to a method for operating the solar module (1).