Solar Module Circuit Layout for Long Strings Under Partial Shading
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Solution Overview
Problem
Existing solar module designs face challenges in interconnecting more than 20 solar cells in series without exceeding safe reverse voltage thresholds during shading, leading to power losses and increased costs due to the need for additional bypass diodes and complex layouts.
Innovation Solution
An electronic circuit is implemented to maintain a minimum string voltage, ensuring that the reverse voltage of shaded solar cells does not exceed a certain value, allowing for more cells to be connected in series while preventing damage and optimizing module efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If more than 20 solar cells are interconnected in series in a solar module, then the open circuit voltage of the module increases, but the reverse voltage at shaded solar cells exceeds safe limits causing cell destruction
Solution Approach 1:
The solar module divides the series-connected solar cells into multiple groups, with each group having its own bypass diode. This segmentation allows the reverse voltage to be distributed across multiple diodes rather than one diode handling all cells, enabling safe operation with more than 20 series-connected cells while preventing voltage breakdown at shaded cells.
2Reliability
If bypass diodes are added to protect shaded solar cells in long strings, then cell protection is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The bypass diodes are designed to serve multiple functions: protecting shaded cells from reverse voltage breakdown, enabling longer cell strings without additional diodes, and maintaining module performance under partial shading conditions. This multi-functionality reduces the need for additional protective components and simplifies the overall device design.
3Power
If the number of solar cells per module is increased beyond 60 or 72, then the power output of the module increases, but the reverse voltage during shading causes avalanche breakdown and hotspots
Solution Approach 1:
The patent implements bypass diodes in a segmented configuration that provides preemptive protection against reverse voltage breakdown. By having multiple diodes strategically placed throughout the cell string, the system cushions against potential avalanche breakdown and hotspot formation before they can occur, enabling safer operation with higher numbers of series-connected 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 solution enables the interconnection of up to 60 cells in series without power loss, reduces the need for additional bypass diodes, and maintains module efficiency, even at low irradiance levels, while ensuring the reverse voltage remains within safe limits.
Implementation Method 1
The maximum reverse voltage that a solar cell can tolerate on a sustained basis is in the −13 V range. This means that each bypass diode may be interconnected in parallel to a maximum of 20 solar cells.
Implementation Method 2
Solar cells (101) are interconnected in solar modules (100) according to the state of the art as shown in FIG. 1.
Data Source
AI summary
The present invention relates to an electronic circuit for photovoltaic modules, which circuit ensures that the magnitude of the reverse voltage of each solar cell in a solar module does not exceed a particular value at any time. The problem solved by the invention is that of ensuring that the electrical voltage of each solar cell string within the photovoltaic module does not fall below a particular value.