Solar Cell Module Overlap Resin Stress Distribution

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Solution Overview

Problem

The existing solar cell module manufacturing techniques that overlap adjacent solar cells to improve cell filling factor lead to reduced load bearing and thermal cycling resistance due to stress concentration at the solar cell/wiring member interface, potentially causing cracks and decreased performance.

Innovation Solution

Incorporating a resin layer between the solar cells and the wiring member in the overlapping portions of the solar cell module, with encapsulants having a storage modulus of 20 MPa or lower at room temperature and 0.5 MPa or lower at 100°C, to distribute stress and enhance mechanical flexibility and thermal cycling resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If two adjacent solar cells are connected such that portions of the respective solar cells overlap, then the gap between the two solar cells is eliminated and the cell filling factor is improved, but the load bearing and thermal cycling resistance may be reduced

Engineering Contradiction:

Improvecell filling factorVSAvoidload bearing and thermal cycling resistance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces a resin layer as an intermediary substance between the overlapping solar cells and the wiring member. This resin layer acts as a stress-distributing medium that prevents direct contact and stress concentration at the solar cell-wiring member interface, thereby maintaining mechanical strength and thermal cycling resistance while allowing the overlapping configuration for improved filling factor.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent specifies particular parameters for the resin layer including storage modulus requirements (20 MPa or lower at room temperature, 0.5 MPa or lower at 100°C) and thickness (1 mm or less). These parameter changes in the intermediate material enable it to effectively distribute stress while maintaining the structural integrity needed for load bearing and thermal cycling resistance.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a resin layer is added between the solar cells and wiring member to distribute stress, then the load bearing and thermal cycling resistance are improved, but the device complexity and manufacturing steps increase

Engineering Contradiction:

Improveload bearing and thermal cycling resistanceVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the resin layer application with the existing encapsulation process. The resin is applied to the back surface of the first solar cell before the second solar cell is positioned, and the entire assembly is then encapsulated together in a single lamination step. This merging of steps adds the stress-distribution function without significantly increasing the number of discrete manufacturing operations.

Inventive Principle:

Principle #5Merging (Combining)

3Strength

If the resin layer is made thinner to maintain structural integrity, then the load bearing is improved, but the stress distribution effect may be reduced

Engineering Contradiction:

Improveload bearingVSAvoidstress distribution capability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent specifies that the resin layer thickness should be 1 mm or less, and defines specific storage modulus parameters (20 MPa or lower at room temperature, 0.5 MPa or lower at 100°C). These parameter specifications ensure the resin layer is thin enough to maintain structural integrity and load bearing while still being sufficient to distribute stress effectively. The low storage modulus values ensure adequate stress distribution even at minimal thickness.

Inventive Principle:

Principle #35Parameter changes

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 resin layer effectively reduces stress concentration and prevents cracking, thereby maintaining load bearing and thermal cycling resistance while improving the solar cell module's reliability and efficiency.

Implementation Method 1

sandwiching the string by a protection member and an encapsulant having a storage modulus at room temperature of 20 MPa or lower and a storage modulus at 100° C. of 0.5 MPa or lower

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 2

laminating a stack to induce a temperature of 100° C. or higher in the encapsulant

Methodology Applied

Scientific EffectPhase transition: Phase Change

Data Source

PatentUS11522095B2Solar cell module including solar cells, method of manufacturing solar cell module

Publication Date: 2022.12.06 PANASONIC HOLDINGS CORP

AI summary

A 12th solar cell and a 13th solar cell are provided to overlap in part as viewed from a side of a light receiving surface 22. A portion of a light receiving surface of the 12th solar cell and a portion of a back surface of the 13th solar cell face each other in an overlapping portion across a wire. The overlapping portion includes a part where a resin is located both between the light receiving surface of the 12th solar cell and the wire and between the back surface of the 13th cell and the wiring member.