Bifacial Solar Cell Electrodes Using Copper Gridlines

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Solution Overview

Problem

Conventional solar cells suffer from reduced energy-conversion efficiency due to shading caused by metal grids, which block sunlight and increase series resistance, leading to power losses and higher costs.

Innovation Solution

The use of bifacial tunneling junction solar cells with electroplated Cu gridlines and a single busbar or tab configuration to reduce shading and series resistance, along with cell-level maximum power point tracking (MPPT) devices to optimize power output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal grid is used for electrodes in conventional solar cells, then electrical conductivity is improved, but shading increases and energy conversion efficiency deteriorates

Engineering Contradiction:

Improveelectrical conductivityVSAvoidenergy conversion efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the material parameter from conventional metal (silver, aluminum) to copper, which has superior electrical conductivity. This parameter change allows for reduced electrode thickness and width while maintaining conductivity, thereby reducing shading losses and improving energy conversion efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies different electrode configurations to different regions of the solar cell. Copper gridlines are used in specific patterns with optimized width and spacing, providing high conductivity where needed while minimizing shading in active light-absorbing regions

Inventive Principle:

Principle #3Local quality

2Reliability

If a metal grid is used for electrodes in conventional solar cells, then electrical conductivity is improved, but series resistance increases leading to power losses

Engineering Contradiction:

Improveelectrical conductivityVSAvoidpower losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the material parameter from conventional metal (silver, aluminum) to copper, which has superior electrical conductivity. This parameter change reduces series resistance in the electrode network, minimizing I²R power losses while maintaining electrical connectivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a segmented electrode design with multiple narrow copper gridlines distributed across the solar cell surface. This segmentation creates multiple parallel current collection paths, reducing the overall series resistance and power losses compared to fewer, wider electrodes

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If conventional solar cell fabrication is used, then manufacturing process is established, but fabrication costs are high

Engineering Contradiction:

Improvemanufacturing processVSAvoidfabrication costs

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent changes the material parameter from expensive conventional metals (silver, aluminum) to copper, which is more abundant and cost-effective. This parameter change reduces material costs while maintaining or improving electrical performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs copper, a cheaper and more abundant material compared to traditional silver or aluminum electrodes. This substitution reduces material costs and fabrication expenses while achieving superior electrical conductivity and performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 achieves up to an 18% gain in power output by minimizing shading and series resistance, while reducing fabrication costs and recouping 30% of power lost due to partial shading through MPPT technology.

Implementation Method 1

A respective solar cell includes a multi-layer semiconductor structure, a front-side electrode situated above the multi-layer semiconductor structure, and a back-side electrode situated below the multi-layer semiconductor structure. Each of the front-side and the back-side electrodes comprises a metal grid.

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 2

The single busbar is configured to collect current from the finger lines.

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Implementation Method 3

A solar cell converts light into electricity using the photovoltaic effect.

Methodology Applied

Scientific EffectPhotovoltaic Effect: Photovoltaic Effect

Data Source

PatentUS10164127B2Module fabrication of solar cells with low resistivity electrodes

Publication Date: 2018.12.25 TESLA INC

AI summary

One embodiment of the present invention provides a solar module. The solar module includes a front-side cover, a back-side cover, and a plurality of solar cells situated between the front- and back-side covers. A respective solar cell includes a multi-layer semiconductor structure, a front-side electrode situated above the multi-layer semiconductor structure, and a back-side electrode situated below the multi-layer semiconductor structure. Each of the front-side and the back-side electrodes comprises a metal grid. A respective metal grid comprises a plurality of finger lines and a single busbar coupled to the finger lines. The single busbar is configured to collect current from the finger lines.