Back-Contact Solar Cell Layout for Lower Recombination Loss
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Solution Overview
Problem
The existing all-back electrode solar cell design is limited by parasitic absorption and recombination due to emitters with the same polarity covering a smaller area, restricting efficiency improvement.
Innovation Solution
A solar cell design where the first polarity metal gate line penetrates insulating material locally to contact the first polarity emitter, minimizing its area fraction and ensuring the second polarity emitter occupies most of the area, thereby reducing parasitic absorption and recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the first polarity emitter with the same polarity as the substrate is minimized in area, then parasitic absorption and recombination are reduced, but the metal gate line cannot adequately contact the emitter
Solution Approach 1:
The metal gate line is segmented into two functional parts: a first part that penetrates the insulating material to contact the first polarity emitter, and a second part that covers the second polarity emitter while being insulated from it. This segmentation allows the gate line to fulfill multiple contact functions while minimizing parasitic effects.
Solution Approach 2:
An insulating material is introduced as an intermediary between the metal gate line and the second polarity emitter. This insulating layer allows the metal gate line to be positioned over the second polarity emitter for structural support and electrical isolation, while preventing harmful electrical contact and parasitic absorption.
2Productivity
If the second polarity emitter area fraction is increased, then conversion efficiency is improved, but the metal gate line width must be increased which complicates the structure
Solution Approach 1:
The metal gate line is designed to serve multiple functions simultaneously: it provides electrical contact to the first polarity emitter through the insulating material, provides structural support over the second polarity emitter, and maintains electrical isolation from the second polarity emitter. This multi-functionality allows the second polarity emitter to occupy most of the area without requiring separate support structures.
3Productivity
If the first polarity emitter area is minimized, then conversion efficiency is improved, but the metal gate line cannot provide adequate electrical contact
Solution Approach 1:
The insulating material is applied selectively rather than uniformly across the entire surface. It is positioned specifically in regions where electrical isolation from the second polarity emitter is needed, while allowing the metal gate line to contact the first polarity emitter through designated penetration points. This local application of insulation maintains both efficiency and contact reliability.
Data Source
Figure 1~2
AI summary
Embodiments of the present disclosure relate to, but are not limited to, a solar cell (100), including: a substrate (110); a first polarity emitter (120) in contact with the substrate (110) and having the same polarity as the substrate (110); a second polarity emitter (130) in contact with the substrate (110) and having an opposite polarity to the substrate (110); and a first polarity metal gate line (140) in contact with the first polarity emitter (120), where the first polarity metal gate line (140) only penetrates an insulating material (170) locally to contact the first polarity emitter (120), while a part of other regions of the first polarity metal gate line (140) covers the second polarity emitter (130) with the insulating material (170) in between and is insulated from the second polarity emitter (130) via the insulating material (170).