Shingled Solar Cell Bonding With Soft Spacers to Prevent Cracking
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Solution Overview
Problem
Crystalline silicon solar cells bonded with hard spacers are prone to cracking under pressure, and traditional ribbon-connected solar cells suffer from reduced efficiency due to blocked sunlight and gaps that reduce active illuminated area.
Innovation Solution
Utilizing soft spacers in an electrically conductive adhesive to bond crystalline silicon solar cells in a shingled manner, which mitigates cracking and ensures even bond line thickness, enhancing efficiency by eliminating gaps and reducing ohmic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard spacers are used in the electrically conductive adhesive, then the bond line thickness is well-defined, but the solar cells crack under pressure
Solution Approach 1:
The patent changes the physical parameter of the spacer material from hard to soft, specifically using materials with a Shore A durometer between 20-80. This parameter change allows the spacers to deform under pressure rather than transmitting stress to the solar cells, thereby preventing cracking while still maintaining bond line thickness control through their compressible nature
Solution Approach 2:
The patent uses composite materials in the electrically conductive adhesive formulation, combining soft spacer particles with conductive metal particles (silver, copper, or aluminum) and a polymer binder. This composite approach allows the soft spacers to provide mechanical compliance while the conductive particles maintain electrical conductivity, and the binder provides adhesive strength
2Reliability
If traditional ribbon connections are used, then the solar cells are electrically connected, but sunlight is blocked and active illuminated area is reduced
Solution Approach 1:
The patent extracts and eliminates the traditional metal ribbon interconnectors from the solar cell assembly. By removing these ribbons entirely and replacing them with edge-to-edge bonded solar cells using conductive adhesive, the design eliminates the components that block sunlight and create gaps, thereby maximizing the active illuminated area while maintaining electrical connectivity through the adhesive bonding method
Solution Approach 2:
The patent merges the electrical connection function and the mechanical bonding function into a single edge-to-edge bonded joint using electrically conductive adhesive. This eliminates the need for separate ribbon interconnectors and gaps between cells, allowing adjacent solar cells to be directly bonded together in a shingled configuration that maximizes illuminated area while maintaining reliable electrical series connections
3Ease of manufacture
If gaps exist between solar cells, then the cells are easier to assemble, but ohmic losses increase and efficiency decreases
Solution Approach 1:
The patent merges adjacent solar cells into a continuous shingled array with edge-to-edge bonding, eliminating gaps between cells. The conductive adhesive creates direct electrical contact between the metallization patterns of adjacent cells, reducing current path length and resistance. This merging approach maintains assembly ease through the flexibility of the adhesive bonding process while dramatically reducing ohmic losses by eliminating air gaps and minimizing current travel distance
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
The use of soft spacers in a conductive adhesive maintains structural integrity while increasing efficiency by utilizing the entire solar module area for power generation and reducing ohmic losses, thus improving the overall performance of solar modules.
Implementation Method 1
The electrically conductive adhesive comprises electrically conductive particles, a cured binder, and spacers. The electrically conductive adhesive bonds the front contact pads of the first solar cell to the rear contact pads of the second solar cell.
Implementation Method 2
The spacers in the electrically conductive adhesive establishes a minimum distance between the front contact pad and the rear contact pad.
Implementation Method 3
The use of soft spacers in the electrically conductive adhesive is advantageous because it mitigates against solar cells cracking when pressure is applied to the solar module or panel.
Data Source
AI summary
A high efficiency configuration for a solar cell module comprises solar cells arranged in an overlapping shingled manner and conductively bonded to each other in their overlapping regions to form super cells, which may be arranged to efficiently use the area of the solar module. Solar cells are conductive bonded to each other with electrically conductive adhesive containing soft spacers.