Photovoltaic Module String Layout for Partial Shading Isolation
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Solution Overview
Problem
Conventional photovoltaic modules experience reduced power generation efficiency due to partial shading of photovoltaic cells, which activates bypass diodes and leads to power loss in multiple strings connected in series.
Innovation Solution
The photovoltaic module incorporates a configuration with turn-back portions and bus bars, where each photovoltaic cell connection unit is connected in parallel with a bypass diode, reducing the impact of shading on power generation by isolating affected units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass diodes are provided inside a terminal box for the entire photovoltaic string, then power generation can be maintained when a string fails, but partial shading of photovoltaic cells causes power loss in multiple strings connected in series
Solution Approach 1:
The photovoltaic string is divided into multiple independent photovoltaic cell connection units (e.g., 6 cells per unit), each with its own bypass diode connection. This segmentation allows only the shaded unit to activate its bypass diode while other units continue generating power, preventing power loss in entire strings as in conventional designs.
Solution Approach 2:
Each photovoltaic cell connection unit is equipped with its own bypass diode connection through turn-back portions and output wiring members. This local protection approach ensures that bypass functionality is distributed to each unit rather than applied globally to the entire string, enabling localized response to shading conditions.
2Power
If multiple photovoltaic strings are connected in series to form groups, then voltage output is increased, but partial shading activates bypass diodes and causes power loss across multiple strings
Solution Approach 1:
The series-connected string is segmented into multiple photovoltaic cell connection units with independent bypass capabilities. This allows the system to maintain high voltage output through series connection while preventing cascading power loss by isolating shading effects to individual units rather than affecting multiple strings.
3Ease of manufacture
If conventional terminal box structure is used with output wiring members drawn from back surface, then terminal box can be easily attached, but bypass diodes cannot provide localized protection to individual photovoltaic cell connection units
Solution Approach 1:
The terminal box structure is modified to include multiple turn-back portions and output wiring members that distribute bypass diode connections to each photovoltaic cell connection unit. This maintains the ease of terminal box attachment while enabling localized protection that prevents power loss in multiple strings during partial shading.
Solution Approach 2:
Turn-back portions are introduced to route output wiring members from the front surface side of photovoltaic cells to the back surface, creating a three-dimensional wiring path. This allows bypass diode connections to reach individual photovoltaic cell connection units while maintaining the conventional terminal box attachment method.
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 mitigates the decrease in power generation efficiency by confining the impact of shading to a single photovoltaic cell connection unit, preventing hot spots and maintaining power output from unaffected units.
Implementation Method 1
The terminal box includes a plurality of bypass diodes. Each of the plurality of photovoltaic cell connection units is connected in parallel with corresponding one of the bypass diodes.
Implementation Method 2
A photovoltaic module includes photovoltaic strings in which a plurality of photovoltaic cells as power generating elements is electrically connected in series.
Data Source
AI summary
A photovoltaic module includes a plurality of photovoltaic cell connection units in each of which a plurality of photovoltaic cells adjacent to each other in a first direction is connected in series with each other. Two of the photovoltaic cell connection units, the two being adjacent in a second direction orthogonal to the first direction, are connected in series with each other by bus bars to constitute a photovoltaic string. An end of an output wiring member is connected to a starting end or a terminating end of the photovoltaic cell connection unit, and another end of the output wiring member establishes electrical continuity with a terminal box. The terminal box includes bypass diodes, and each of the plurality of photovoltaic cell connection units is connected in parallel with corresponding one of the bypass diodes.