Solar Cell Arrays with Tunneling Junctions
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Solution Overview
Problem
Conventional solar cells face issues with high material usage, mechanical stress, and weight due to metal traces, leading to inefficiencies and potential failures, especially in applications like aerospace, where weight is critical. Additionally, the assembly process is complex and costly, with significant steps required to form interconnected arrays.
Innovation Solution
The development of an array of interconnected photovoltaic cells using tunneling junctions and a manufacturing method that includes partial processing of wafers, singulation with lasers, and flexible insulating layers to reduce metal usage and simplify assembly, allowing for flexible and robust cell configurations with reduced power losses and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If metal traces are used to interconnect solar cells, then electrical conductivity is improved, but weight and material usage increase
Solution Approach 1:
The patent replaces traditional metal trace interconnection with a direct semiconductor-to-semiconductor bonding approach, eliminating the need for separate metal interconnect layers. This substitution reduces both weight and material complexity while maintaining electrical conductivity through direct carrier transport across bonded cell surfaces.
Solution Approach 2:
The invention extracts and removes the metal trace layer from the solar cell structure, using only necessary metallization for contact formation while eliminating extensive metal interconnection networks. This extraction reduces material usage and weight while preserving essential electrical functions.
2Reliability
If metal traces are deposited onto solar cells, then electrical connection is achieved, but mechanical stress and weak points increase
Solution Approach 1:
The patent replaces the metal trace deposition and welding process with direct semiconductor bonding. This eliminates thermal processing steps that cause stress and avoids creating weak points at metal-semiconductor interfaces, thereby improving structural reliability.
Solution Approach 2:
The invention performs preliminary surface preparation and bonding interface preparation before final cell assembly, ensuring proper alignment and contact. This preliminary action prevents misalignment stresses and ensures uniform contact pressure across bonded surfaces.
3Productivity
If conventional assembly processes are used to form solar cell arrays, then electrical interconnection is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges multiple separate assembly steps (cell alignment, metallization, bonding, and encapsulation) into an integrated manufacturing process. By combining these operations and using direct semiconductor bonding, the process reduces the total number of steps while maintaining interconnection quality.
Solution Approach 2:
The invention creates a universal bonding interface that can accommodate different cell types and configurations without requiring specialized assembly equipment or processes. This multi-functional approach simplifies manufacturing by using the same basic process for various array configurations.
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 approach results in high-performance solar cell arrays with reduced material usage, lower power losses, and simplified assembly, enhancing mechanical and electrical resilience while minimizing weight, making them suitable for critical applications like aerospace.
Implementation Method 1
using a laser to singulate individual photovoltaic cells from the wafer
Implementation Method 2
adhering the wafer to a stretchable carrier
Data Source
Figure 1(a)~1(d)
Figure 2~3
Figure 4
AI summary
High performance single crystal silicon cells and arrays thereof are manufactured using a rapid process flow. Tunneling junctions formed in the process provide performance benefits, such as higher efficiency and a lower power temperature coefficient. The process generates a large array of interconnected high performance cells smaller than typical cells without requiring additional process steps, and simplifies integration of these coupons into the final product. The cells can have different shapes, sizes, and orientations, enabling the array to be flexible in any desired direction. Higher efficiencies and lower hot spotting under shading is achieved by connecting small low current, high voltage cells in dense series and parallel configurations. Low current cells also require much less metallization than typical solar cells and arrays.