Photovoltaic Cell-String Layout for Partial Shading Resilience
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Solution Overview
Problem
Existing solar module layouts are not sufficiently resilient against partial shading, leading to issues such as overheating, reduced efficiency, and increased assembly effort, particularly with half-cut solar cells, and require complex control units like micro-inverters or power optimizers.
Innovation Solution
A solar module layout with alternating series and parallel connections of substrings, utilizing a sequence of polarities in end terminals and insulated cross-connections to enhance resilience against partial shading without increasing assembly complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If all solar cells are interconnected in series with a standard layout, then the assembly effort is reduced and the module structure is simplified, but the module becomes highly sensitive to partial shading leading to overheating and reduced efficiency
Solution Approach 1:
The solar module is divided into multiple independent parallel substrings instead of a single series connection. Each substring contains a portion of the solar cells connected in series, and these substrings are connected in parallel to each other. This segmentation allows current to flow through alternative paths when partial shading occurs, preventing the entire module from being affected and eliminating the need for complex control units.
2Loss of energy
If half-cut solar cells are used in a standard layout, then resistive losses are reduced, but the number of substrings must be increased requiring split module zones and multiple junction boxes
Solution Approach 1:
Multiple parallel substrings are combined into a single unified electrical structure that connects to one junction box. The parallel configuration allows all substrings to share common connection points, eliminating the need for multiple separate junction boxes and split module zones while maintaining the low resistive losses achieved through half-cut solar cells.
3Device complexity
If the number of solar cells per substring is increased to reduce the number of substrings, then the module structure is simplified, but the reverse bias voltage on shaded cells increases causing overheating
Solution Approach 1:
The electrical configuration parameter is changed from series connection to parallel connection of substrings. This parameter change fundamentally alters the voltage distribution characteristics: in parallel configuration, each substring experiences the same voltage, preventing the accumulation of high reverse bias voltage on individual shaded cells that would occur in series configurations with more cells per substring.
4Reliability
If multiple junction boxes with bypass diodes are used to protect against shading, then resilience against partial shading is improved, but the assembly effort and device complexity increase significantly
Solution Approach 1:
The parallel substrate configuration provides inherent self-protection against partial shading without requiring additional protective components. The natural current distribution in parallel circuits automatically routes current around shaded areas, making bypass diodes and multiple junction boxes unnecessary and simplifying the overall assembly process.
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 layout significantly enhances energy yield and reduces resistive losses in partial shading scenarios, maintaining efficiency and simplifying assembly by eliminating the need for split module designs and additional control units.
Implementation Method 1
solar cells 101 are interconnected to solar module zones of solar modules 100
Implementation Method 2
Each substring 104 is connected to a bypass diode 103 in an anti-parallel fashion. In case a substring 104 is shaded, the bypass diode 103 becomes active and bypasses the shaded substring 104
Data Source
AI summary
The present invention relates to a solar module zone (110) of a solar module (100), the solar module zone (110) comprising an array of solar cells (101,201) arranged in pairs of substrings (104) along columns of the array, wherein each substring (104) comprises a plurality of solar cells (101,201) electrically connected in series along the column the substring (104) extends in; each pair of substrings (104) comprises two substrings (104) that extend along the columns, particularly adjacent columns, and that are electrically connected in series, and wherein all pairs of substrings (104) are electrically connected in parallel; each pair of substrings (104) comprises a positive and a negative end terminal (105) for connecting the pair of substrings (104) to a plus and a minus pole of the solar module (100), wherein the negative and the positive end terminals (105) of each pair of substrings (104) are located adjacent to each other in an end terminal-connecting portion of the solar module zone (110), particularly solar module (100), such that the end terminals (105) of the pairs of substrings (104) form a sequence of end terminals (105) along the columns having a sequence of polarities; wherein the sequence of polarities of the end terminals (105) comprises at least two changes of polarity of adjacent end terminals (105), characterized in that the sequence of polarity of the end terminals (105) comprises the following sequence of polarity: positive, negative, negative, positive, positive, negative or vice versa. The invention also relates to a solar module (100) comprising such a solar module zone (110) as well as a photovoltaic system (111).