Backside Contact Solar Cell Insulator Gap Design
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Solution Overview
Problem
Existing backside contact solar cells face issues with high consumption of insulating material and unclear impact on photoelectric conversion efficiency due to bus bar electrode placement, leading to decreased parallel resistance and electrical contact challenges.
Innovation Solution
A solar cell design featuring dielectric films and insulator films with strategically placed gaps between the base bus bar electrode and emitter region, optimizing the distance between insulator films to 40 μm or more and (W+110) μm or less, ensures efficient electrical contact and reduced material consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulator films are provided in the entire region below bus bar electrodes to prevent direct contact with substrate, then direct contact between bus bar electrodes and substrate is avoided, but a large amount of insulating material is consumed
Solution Approach 1:
The insulator film is segmented into multiple regions: it is provided in contact with the base layer and emitter layer in specific regions, but has gaps in other regions. This segmentation allows the insulator film to prevent direct contact between bus bar electrodes and substrate in critical areas while reducing overall material consumption by eliminating unnecessary coverage in non-critical areas.
Solution Approach 2:
The insulator film is applied with varying coverage: full coverage in regions where electrical isolation is critical (contact with base layer and emitter layer), and gaps in regions where isolation is less critical. This local quality approach optimizes the balance between reliability and material consumption by applying insulation only where needed.
2Loss of energy
If bus bar electrodes are placed to reduce wiring resistance of collecting electrodes, then wiring resistance is reduced, but parallel resistance decreases due to contact between base bus bar electrode and emitter region
Solution Approach 1:
The insulator film acts as an intermediary between the base bus bar electrode and the emitter region. By strategically positioning the insulator film to have gaps in specific regions, it allows controlled electrical contact where needed for low wiring resistance while preventing harmful contact in regions that would reduce parallel resistance, thus mediating between these two conflicting requirements.
3Reliability
If insulator film coverage is increased to prevent electrical contact issues, then electrical isolation is improved, but material consumption and manufacturing complexity increase
Solution Approach 1:
The insulator film pattern is segmented into distinct regions with different coverage levels, simplifying the overall design by clearly defining where insulation is needed and where gaps should exist, rather than using a complex continuous coverage pattern.
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 design alleviates decreases in parallel resistance, maintains excellent electrical contact, and enhances solar cell characteristics while minimizing insulator material usage, improving overall photoelectric conversion efficiency and productivity.
Implementation Method 1
dielectric films which are in contact with the base layer and the emitter layer on the first main surface; first insulator films which cover the emitter electrode, are placed on the dielectric films, and are arranged to have a gap at least on the base layer
Data Source
AI summary
A solar cell having, on a semiconductor substrate's first main surface a first conductivity type, a base layer having first conductivity type and an emitter layer which is adjacent to base layer and has a second conductivity type which is a conductivity type opposite to first conductivity type, the solar cell includes: a base electrode which is electrically connected with base layer; and an emitter electrode which is electrically connected with emitter layer, solar cell including: dielectric films which are in contact with base and emitter layer on first main surface; first insulator films which cover the emitter electrode, are placed on the dielectric films, and are arranged to have a gap at least on base layer; and a base bus bar electrode placed at least on first insulator films, and being wherein gap distance between the first insulator films is 40 μm or more and (W+110) μm or less.