Smart Photovoltaic Cells with Cell-Level Bypass Switches
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Solution Overview
Problem
Conventional crystalline silicon PV modules face significant energy yield reduction and reliability issues due to shading, which leads to hot spots and potential fire hazards, as external bypass diodes shunt entire sub-strings when a single cell is shaded, resulting in substantial power loss and module failure.
Innovation Solution
Integration of a bypass switch and DC-to-DC or DC-to-AC MPPT power optimizer directly on the backside of each solar cell, eliminating the need for external junction boxes and enabling distributed shade management and maximum power point tracking at the cell level, thereby minimizing hot spots and enhancing energy yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external bypass diodes are used to protect against shading, then reliability is improved, but energy yield is reduced due to shunting entire sub-strings
Solution Approach 1:
The patent divides the module into independently controllable cell-level units, with each cell having its own bypass switch and power optimizer. This segmentation allows individual cells to be protected from shading effects without forcing the entire sub-string to shut down, thereby maintaining energy yield while providing reliability protection.
Solution Approach 2:
The patent implements dynamic control through electronically controllable bypass switches and MPPT power optimizers at each cell level. These components can dynamically adjust their operation based on real-time shading conditions, allowing the system to maintain maximum power extraction from unshaded cells while protecting shaded cells, rather than statically shutting down entire sub-strings.
2Object-affected harmful factors
If external bypass diodes are used, then hot spots are prevented, but system complexity increases due to external junction boxes
Solution Approach 1:
The patent merges the bypass functionality and power optimization into integrated cell-level modules that are directly attached to each solar cell. This eliminates the need for separate external junction boxes and sub-string level bypass diodes, reducing system complexity while maintaining hot spot protection through the electronic bypass switches at each cell.
Solution Approach 2:
The patent transitions from a sub-string level protection approach (2D organization with multiple cells per string) to a cell-level approach (1D organization with individual protection). By moving the bypass functionality to the cell level, the system achieves simpler architecture without external junction boxes while maintaining comprehensive hot spot protection.
3Reliability
If external bypass diodes are used, then module failure is prevented, but manufacturing cost increases
Solution Approach 1:
The patent segments the protection functionality to the cell level, allowing for standardized, mass-producible cell-level modules. This segmentation enables independent manufacturing and testing of small units, reducing overall manufacturing complexity and cost compared to assembling large sub-string level bypass systems.
Solution Approach 2:
The patent implements self-service through integrated power optimizers that automatically perform maximum power point tracking and bypass operations at each cell level without external control. This eliminates the need for complex external control systems and reduces manufacturing costs through automated, cell-level autonomous operation.
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 solution significantly increases energy harvesting and reliability by allowing power extraction from shaded cells, reducing system costs, and improving the levelized cost of electricity (LCOE) to less than $0.10/kWh, while eliminating the need for external bypass diodes and junction boxes.
Implementation Method 1
A solar cell may be represented as a current source, producing the photo-generation current shown as IL
Data Source
AI summary
A back contact solar cell comprises an active semiconductor absorber for use in a back contact solar cell having a light capturing front side and a backside opposite the light capturing front side. A first interdigitated metallization is positioned over the backside of the active semiconductor absorber. The first interdigitated metallization forming base and emitter contact metallization of the back contact solar cell. A backplane is positioned over the backside of the active semiconductor absorber and the first interdigitated metallization. A second interdigitated metallization is positioned over the backplane. The second interdigitated metallization is connected to the first interdigitated metallization for extracting photovoltaic power from the active semiconductor absorber. The second interdigitated metallization has base and emitter busbars over the backplane for electrical connection. An electronic component is electrically connected to at least a base busbar and at least an emitter busbar of the second interdigitated metallization. The electronic component has a bypass switch.