Edge-Mounted Solar Junction Box with Sealed Flap
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Solution Overview
Problem
Existing solar junction boxes face challenges in sealing and light efficiency due to their design, which can lead to damage and water ingress, especially when terminating junction boxes at the edge of solar panels with varying glass thicknesses and bifacial panels that collect reflected sunlight.
Innovation Solution
A solar junction box with a housing that mounts at the edge of the solar panel, featuring a terminal cavity and an edge flap with a seal that can accommodate different panel thicknesses, ensuring secure termination and sealing of the foil while allowing sunlight to pass through, thereby enhancing efficiency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the junction box is mounted at the center of the back sheet, then the electrical connection is stable, but the foil is exposed and susceptible to damage and water ingress
Solution Approach 1:
The housing is divided into a front portion and a rear portion that can be separately assembled. The front portion includes a front wall that provides structural support and mounting surface, while the rear portion includes a rear wall that forms the sealing cavity. This segmentation allows the housing to simultaneously provide stable mounting and protective sealing functions.
Solution Approach 2:
A seal member is introduced as an intermediary element between the housing and the back sheet. The seal member includes a first sealing surface that contacts the back sheet and a second sealing surface that contacts the foil, creating a protective barrier that prevents water ingress while maintaining electrical connection stability.
2Reliability
If the junction box blocks the back sheet, then the electrical connection is achieved, but reflected sunlight is blocked in bifacial panels
Solution Approach 1:
The sealing and electrical connection functions are extracted from a traditional solid junction box structure and redistributed into the hollow housing cavity. The housing walls are designed to be transparent or translucent in regions where sunlight needs to pass through, allowing the junction box to maintain electrical connection while permitting reflected sunlight to reach the PV cells in bifacial panels.
Solution Approach 2:
Different portions of the housing have different optical properties. The front wall and portions of the side walls are designed to be transparent or translucent to allow sunlight transmission, while the rear wall and sealing portions maintain opacity for effective sealing. This local differentiation of material properties resolves the contradiction between electrical connection and light transmission.
3Strength
If adhesive is applied to the solar panel to adhere the housing, then the housing is securely mounted, but the sealing effectiveness is compromised
Solution Approach 1:
The mounting and sealing functions are separated into distinct structural elements. The housing walls provide the primary mounting surface through mechanical attachment to the back sheet, while the seal member provides the sealing function. This segmentation prevents adhesive from interfering with the sealing interface.
Solution Approach 2:
The seal member acts as an intermediary between the housing and the back sheet, providing a dedicated sealing interface that is independent of the mounting mechanism. The seal member can be compressed or deformed to create effective sealing without requiring adhesive, while the housing provides structural mounting support.
4Reliability
If the foil is routed through the glass layer by drilling holes or slots, then the electrical connection is achieved, but the manufacturing cost increases
Solution Approach 1:
Instead of routing the foil through the glass layer from the front, the housing is mounted on the back sheet and the foil is routed from the back side through the housing cavity to the front. This inverted routing approach eliminates the need to drill holes or slots through the glass layer, reducing manufacturing complexity and cost while maintaining reliable electrical connection.
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 solution provides a secure and efficient termination of the foil connections, preventing damage and water ingress while maintaining light efficiency, particularly for bifacial panels, by using an edge flap that seals the foil at the edge of the solar panel, accommodating various thicknesses and ensuring reliable operation.
Implementation Method 1
An edge seal is provided on the edge flap and is configured to be applied to the edge of the solar panel to seal the foil at the edge of the solar panel
Implementation Method 2
Due to the photovoltaic effect, the energy of photons is converted into electrical power within a PV cell when the PV cell is irradiated by a light source such as sunlight
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
A solar junction box (102) for a solar panel (106) having a semiconductor layer (110) including at least one photovoltaic cell (108) and a foil (116) electrically connected to the at least one cell, the solar panel having a glass layer (112) above the semiconductor layer and a back sheet (114) below the semiconductor layer includes a housing (130) having walls (134) defining a cavity (140). The housing is mounted at an edge (118) of the solar panel. A terminal (150) is received in the cavity and is configured to be terminated to the foil. An edge flap (200) extends from the housing. The edge flap has an edge seal (220) configured to be applied to the edge of the solar panel to seal the foil at the edge of the solar panel.