Bifacial Solar Cell Array with Local Concentrators for Airship Power
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Solution Overview
Problem
Current solar generator systems for stratospheric balloons face challenges such as complex geometric alignment, integration difficulties, reduced efficiency due to transparent envelope requirements, internal heating, and mechanical stress, which complicate design and testing, and result in inefficient energy production and mechanical strain.
Innovation Solution
A compact solar generator with local radiation concentrators arranged outside the balloon, paired with bifacial solar cells, where each local concentrator has a convex reflecting face to converge solar radiation onto the rear faces of the cells, minimizing mechanical and thermal interaction with the balloon envelope and allowing for independent manufacturing and testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a global solar concentrator is installed inside the balloon envelope, then solar radiation can be concentrated onto solar cells, but the geometric alignment becomes complex and integration with the flexible envelope is difficult
Solution Approach 1:
The patent divides the single global concentrator into multiple small local concentrators distributed across the envelope surface. Each local concentrator independently concentrates sunlight onto nearby solar cells, eliminating the complex geometric alignment required for a single large concentrator while maintaining effective solar energy concentration.
Solution Approach 2:
The patent transitions from a centralized 3D concentrator structure to a distributed 2D array of local concentrators integrated directly onto the envelope surface. This dimensional change simplifies alignment requirements while maintaining effective solar energy concentration across the flexible surface.
2Use of energy by moving object
If the envelope is made transparent to solar radiation, then solar rays can reach the concentrator, but the efficiency of the solar generator decreases due to radiation absorption
Solution Approach 1:
The patent extracts the solar concentrators and solar cells from the interior of the envelope and places them on the exterior surface. This eliminates the need for transparent envelope sections, allowing the envelope to be fully opaque while still enabling solar radiation to reach the concentrators without absorption losses.
Solution Approach 2:
Instead of making the envelope transparent to allow solar radiation through to internal concentrators, the patent inverts the approach by placing the concentrators and solar cells on the outside of the envelope, eliminating the transparency requirement entirely.
3Power
If solar radiation enters the balloon, then the concentrator can function, but internal heating increases the internal pressure requiring over-dimensioning of the envelope
Solution Approach 1:
The patent extracts the solar concentration system from the balloon interior and relocates it to the exterior surface. This prevents solar radiation from entering the balloon interior, eliminating internal heating and pressure increase while maintaining full solar concentration functionality.
4Power
If the solar generator is integrated into the envelope, then it can provide power, but the design constraints are coupled making the system difficult to test
Solution Approach 1:
The patent segments the solar generation system into independent modular units (local concentrators with associated solar cells) that can be developed, tested, and manufactured separately from the balloon envelope, then integrated later. This decoupling enables independent testing and simplifies manufacturing.
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 configuration enhances energy efficiency, simplifies production and testing, reduces mechanical and thermal stress on the balloon, and maintains aerodynamics by keeping the solar generator thin compared to the balloon diameter, while avoiding direct contact with the envelope and internal heating.
Implementation Method 1
a reflector, a first reflecting face of which has a surface of convex shape suitable for converging solar radiation towards the rear faces of the solar cells
Implementation Method 2
A compact solar generator with local radiation concentrators arranged outside the balloon, paired with bifacial solar cells, where each local concentrator has a convex reflecting face to converge solar radiation onto the rear faces of the cells
Implementation Method 3
a first set of at least one line of bifacial photovoltaic solar cells
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A dirigible balloon (102) is equipped with a compact concentrating solar generator (104) to supply electrical energy to said balloon (102) in flight from solar radiation. The compact solar generator (104) comprises a first set (122) of row(s) (124, 126, 128, 130, 132) of bifacial photovoltaic solar cells, arranged parallel to a longitudinal central axis (116) of the balloon, and a solar radiation concentrator (136) to focus solar rays onto the rear faces of the bifacial solar cells of the first set (122).The solar radiation concentrator (136) is a second set (156) of one or more local solar radiation concentrator(s) (164, 166, 168, 170, 172), in which each local concentrator (164, 166, 168, 170, 172) is paired with a corresponding row of solar cells and includes a convex-shaped reflector adapted to converge solar radiation towards the rear faces of the solar cells in the paired row.