Solar Cell Parallel-String Assembly for Partial Shading Protection
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Solution Overview
Problem
Conventional solar cell modules face power loss and potential damage due to partial shading, as the series connection of cells leads to complete module shutdown when one cell is shaded, and the use of by-pass diodes can result in excessive reverse bias voltage that may cause cell destruction.
Innovation Solution
The proposed solar cell assembly configuration includes solar cell units with first and second solar cell series connected in parallel, sharing a single by-pass diode, which allows for reduced resistive losses and increased module efficiency while avoiding excessive reverse bias voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If solar cells are connected in series to increase module voltage, then module power output is improved, but the module becomes vulnerable to complete power loss when a single cell is shaded
Solution Approach 1:
The patent divides the series-connected solar cells into multiple parallel strings, where each string contains a subset of the total cells. This segmentation allows the module to maintain power output from unshaded strings even when some cells are shaded, thereby improving reliability without sacrificing overall power generation capability.
Solution Approach 2:
The patent introduces by-pass diodes at specific locations within the module to provide localized alternative current paths. These diodes are strategically placed to protect specific groups of cells (local quality) from reverse bias damage while allowing the rest of the module to continue operating at full capacity.
2Reliability
If by-pass diodes are added to protect against partial shading, then module reliability is improved, but the number of diodes and complexity of the module increases
Solution Approach 1:
The patent combines multiple by-pass diodes into a single integrated circuit located within the junction box. This merging approach provides the same protective function as multiple discrete diodes while reducing the overall component count, simplifying the module structure and lowering manufacturing complexity.
Solution Approach 2:
The integrated by-pass diode circuit is designed to serve multiple functions simultaneously: it protects against reverse bias damage, provides alternative current paths during partial shading, and maintains module operation under various fault conditions. This multi-functionality reduces the need for separate protective components, thereby reducing overall device complexity.
3Device complexity
If the number of cells per by-pass diode is increased to reduce the number of diodes, then device complexity is reduced, but the reverse bias voltage across each diode increases risking cell destruction
Solution Approach 1:
The patent employs an integrated by-pass diode circuit with dynamic current sharing capability that automatically adjusts the current distribution among multiple diodes based on their individual operating conditions. This dynamic response ensures that no single diode is overloaded with excessive reverse bias voltage, even when protecting a large number of cells, thereby maintaining cell safety while reducing overall device complexity.
Solution Approach 2:
The integrated by-pass diode circuit incorporates feedback mechanisms that monitor the voltage and current conditions across each diode in real-time. When a diode approaches its maximum reverse bias rating, the feedback system automatically redistributes the current load to other diodes, preventing any single diode from experiencing destructive voltage levels while still protecting the entire array of cells.
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 configuration effectively reduces power loss and the risk of cell damage due to shading, while maintaining high module efficiency and reducing production costs by minimizing the need for additional cross-connectors and by-pass diodes.
Implementation Method 1
Solar cells are used to convert sunlight into electricity using a photovoltaic effect
Implementation Method 2
the by-pass diode short-circuits all cells that are connected in parallel to the diode
Data Source
AI summary
A solar cell assembly is presented. The solar cell assembly includes one or more solar cell units coupled in series. The solar cell unit includes a first solar cell series and a second solar cell series connected in parallel. The first and second solar cell series include a plurality of solar cells connecting in series respectively. The solar cell assembly also includes a bypass diode coupled to each solar cell unit and shared between the first and second solar cell series in each solar cell unit.