Back Contact Solar Cell String Wire Interconnect Design

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Solution Overview

Problem

Conventional back contact solar cell strings face high production costs due to excessive silver paste consumption and manufacturing difficulties caused by circuitous connections between front and back sides of cell pieces.

Innovation Solution

A back contact solar cell string design where conductive wires directly connect positive and negative electrode thin grid lines on adjacent cell pieces, eliminating the need for busbars and ribbons, with wires cut off between cells to achieve serial connection, reducing silver paste usage and simplifying alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If busbars and ribbons are used for serial connection of back contact solar cells, then electrical connection between cells is achieved, but silver paste consumption increases and production costs rise

Engineering Contradiction:

Improveelectrical connectionVSAvoidsilver paste consumption

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent merges the functions of busbars and ribbons into a single integrated conductive wire system. The conductive wires directly connect the thin grid lines of adjacent cells, eliminating the need for separate busbar and ribbon components, thereby reducing silver paste consumption while maintaining electrical connection reliability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the complex busbar and ribbon structure from the connection system. By using simple conductive wires that directly connect thin grid lines, the invention removes unnecessary components and reduces material consumption without compromising electrical connection functionality

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If busbars and ribbons are used for serial connection, then electrical connection is established, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveelectrical connectionVSAvoidconnection structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the complex busbar and ribbon structure from the connection system. By using simple conductive wires that directly connect thin grid lines, the invention removes unnecessary components and reduces structural complexity while maintaining electrical connection functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using the conventional approach of connecting cells through front-side ribbons and back-side busbars, the patent inverts the connection approach by using conductive wires that connect thin grid lines directly on the back contact surface, simplifying the overall connection structure

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If circuitous connection routes are used from back side to front side, then cell pieces are connected in series, but alignment difficulty and manufacturing problems occur

Engineering Contradiction:

Improveserial connectionVSAvoidcell alignment

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent segments the connection function into simple conductive wires that connect individual thin grid lines, rather than using complex integrated busbar-ribbon systems. This segmentation simplifies the alignment process and reduces manufacturing complexity

Inventive Principle:

Principle #1Segmentation

4Ease of manufacture

If single-side welding is used for cell piece connection, then manufacturing process is simplified, but warping of cell pieces occurs due to stresses

Engineering Contradiction:

Improvewelding processVSAvoidcell piece flatness

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent applies counterbalancing forces during the welding process by using dual-side welding. This counteracts the thermal stresses and mechanical forces that would otherwise cause cell piece warping, maintaining flatness and structural stability while enabling simplified manufacturing

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Data Source

PatentEP4095931A1Back contact solar cell string and manufacturing method therefor

Publication Date: 2022.11.30 ZHEJIANG AIKO SOLAR ENERGY TECH CO LTD

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AI summary

Aback contact solar cell string includes at least two cell pieces, each cell piece including P-type doped regions and N-type doped regions that are alternately arranged, the P-type doped regions including positive electrode thin grid lines, and the N-type doped regions including negative electrode thin grid lines; and a plurality of conductive wires connected to the positive electrode thin grid lines and the negative electrode thin grid lines. The conductive regions configured for electrical connection between each conductive wire and the positive electrode thin grid lines or the negative electrode thin grid lines and insulation regions configured for insulating connection between each conductive wire and the negative electrode thin grid lines or the positive electrode thin grid lines are alternately disposed at joints between each conductive wire and the positive electrode thin grid lines, and at joints between each conductive wire and the negative electrode thin grid lines.