Heterojunction PV Cell Heating Temperature During Line Scanning
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Solution Overview
Problem
The challenge in manufacturing photovoltaic cells with heterojunctions is the difficulty in quickly and precisely determining the warm-up temperature during processing, which is crucial to avoid degrading the amorphous silicon layers while ensuring efficient energy conversion efficiency, as existing methods are either too lengthy or incompatible with current production line rates.
Innovation Solution
A process that calculates the stacking temperature using acquired parameters such as irradiance, relative movement speed, and stack thickness, employing an analytical model to determine the temperature and adjust processing conditions to maintain it below a threshold, thereby preventing amorphous silicon degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the irradiance of the luminous flux is increased to improve energy conversion efficiency, then the heating temperature of the stack increases, but the amorphous silicon layers may be degraded
Solution Approach 1:
The patent applies a preliminary cooling action before the light-soaking treatment by circulating a cooling fluid through channels in the support structure. This pre-cooling measure prepares the stack to withstand the thermal load of high-irradiance treatment without degrading the amorphous silicon layers, allowing the process to proceed at higher irradiance levels for improved productivity.
Solution Approach 2:
The patent introduces a cooling fluid as an intermediary substance that mediates between the heat generated by high-irradiance light-soaking and the amorphous silicon layers. The cooling fluid absorbs excess heat through convection, preventing direct thermal damage to the sensitive amorphous silicon while allowing high irradiance treatment to proceed for improved energy conversion efficiency.
2Reliability
If a conventional light-soaking treatment process is used to improve cell efficiency, then the treatment time is long and complex, but the amorphous silicon layers are protected
Solution Approach 1:
The patent implements periodic action by applying high-irradiance light-soaking treatment in controlled intervals with active cooling between exposure periods. The cooling fluid circulates continuously during treatment, creating a periodic thermal management regime that allows higher irradiance levels to be applied safely, thereby reducing total treatment time while protecting the amorphous silicon layers.
Solution Approach 2:
The patent changes the thermal parameters of the processing environment by actively controlling the temperature of the support structure through cooling fluid circulation. This parameter control allows the system to tolerate higher irradiance levels and shorter treatment times that would otherwise degrade the amorphous silicon, thus reducing treatment time while maintaining protection through dynamic thermal management.
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 method allows for rapid and precise determination of the warm-up temperature, ensuring the photovoltaic cell processing is efficient and compatible with industrial production rates without degrading the amorphous silicon layers, thus improving the energy conversion efficiency and stability of the cells.
Implementation Method 1
acquiring an irradiance of the electromagnetic radiation... calculating the heating temperature of the stack using the following relationship: Φsource represents the quantity of heat per unit volume supplied by the radiation source
Implementation Method 2
k are respectively the density, the mass capacity and the thermal conductivity of the stack
Implementation Method 3
Φext represents the quantity of heat per unit volume exchanged with an external environment... h is a convective exchange coefficient
Data Source
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AI summary
The invention relates to a method for determining a heating temperature (T) of a stack comprising a crystalline silicon substrate and a hydrogenated amorphous silicon passivation layer disposed on the substrate, the heating temperature (T) being reached during a scanning treatment process of the stack, the treatment process comprising a step of exposing one face of the stack to electromagnetic radiation, the electromagnetic radiation being emitted by a radiation source and applied to the face of the stack along a line, the stack and the radiation source being in relative translational motion such that the line sweeps at least a part of the face of the stack, the determination process comprising the following steps: a) acquiring a plurality of parameters of the treatment process, the plurality of parameters comprising an irradiance (E) of the electromagnetic radiation,a) a width (L) of the line and a relative displacement velocity (V) between the stack and the radiation source; b) acquire a thickness (e) of the stack; c) calculate the heating temperature (T) of the stack using the following relation: VρcpΔTcTLc1L=−kΔTcTLc2L2+φsourceEe+φext,