Double-Sided PV Cell Metallization via Segmented Electrolysis
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Solution Overview
Problem
The development of double-sided photovoltaic cells is hindered by the complexity and cost of existing metallization techniques, particularly due to the incompatibility of electrochemical plating methods with both surfaces, leading to performance limitations and high production costs.
Innovation Solution
A method involving a shared electrolysis tank with separate compartments for depositing a metal layer on one surface and a metal oxide layer on the other, assisted by illumination and potential differences, allowing simultaneous electrochemical deposition on both active surfaces of double-sided photovoltaic cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrochemical plating is used for metallization, then productivity and cost-effectiveness improve, but it cannot be applied to both surfaces of double-sided cells simultaneously due to technical incompatibility
Solution Approach 1:
The electrolysis tank is divided into two separate compartments, each dedicated to treating one surface of the double-sided cell. This segmentation allows independent optimization of electrochemical parameters for each surface while enabling simultaneous processing, resolving the incompatibility issue that prevented conventional electrochemical plating from being applied to both surfaces.
Solution Approach 2:
An ion-exchange membrane is introduced as an intermediary between the two electrolysis compartments. This membrane enables selective ion transport while electrically isolating the two compartments, allowing each surface to undergo appropriate electrochemical reactions without interference from the other surface, thus making simultaneous dual-surface metallization possible.
2Reliability
If screen printing with silver paste is used, then metallization is achieved on both surfaces, but shadowing rate increases and electrical conductivity decreases
Solution Approach 1:
The mechanical screen printing process is replaced with electrochemical deposition. This substitution enables precise control of metal layer thickness at the micro-scale, producing thinner metallization patterns that reduce shadowing while maintaining or improving electrical conductivity through better contact with the semiconductor surface.
Solution Approach 2:
The deposition parameters (current density, deposition time, electrolyte composition) are precisely controlled to optimize the metal layer characteristics. By adjusting these parameters, the metallization pattern width can be reduced by over 50% compared to screen printing, significantly reducing shadowing while achieving superior electrical contact properties.
3Quantity of substance
If conventional electrochemical plating is used, then silver usage is reduced and cost decreases, but deposition speed is too slow for industrial production
Solution Approach 1:
The electrolysis system is designed to simultaneously perform metallization on both front and rear surfaces in a single processing step. This multi-functionality doubles the effective deposition throughput compared to sequential single-surface treatment, making the process industrially viable while maintaining low silver consumption through efficient electrochemical deposition.
Solution Approach 2:
Both surfaces are metallized simultaneously in continuous operation within the same electrolysis bath system. The dual-compartment design with ion-exchange membrane allows uninterrupted concurrent deposition on both surfaces, eliminating idle time between surfaces and achieving deposition speeds 10 times greater than conventional electroless methods.
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 enables faster, cost-effective, and high-performance metallization of both surfaces with reduced shadowing, improved conductivity, and lower silver usage, overcoming the limitations of existing methods while achieving deposition speeds 10 times greater than current electroless methods.
Implementation Method 1
The deposition step comprises in particular a shared operation of depositing on each of the active surfaces, implemented by electrolysis in a shared electrolysis tank
Implementation Method 2
deposit induced by light (Light Induced Plating or LIP)... by illuminating the semiconductor, the p-n junction generates electron-hole pairs
Data Source
AI summary
Fabrication of a double-sided photovoltaic cell, with two opposite active surfaces, comprising a step of depositing, on each active surface, at least one electric contact. The deposition step comprises in particular a shared operation of depositing on each of the active surfaces, implemented by electrolysis in a shared electrolysis tank comprising: a first compartment for depositing a metal layer on a first active surface of the cell, for fabrication of a contact comprising said metal layer on the first active surface; and a second compartment for depositing, by oxidation, a metal oxide conductor layer on the second active surface of the cell, for the fabrication of a contact comprising said metal oxide layer on the second active surface.