[Paper Review] Geometrical design of thin film PV modules for improved shade tolerance and performance

Sourabh Dongaonkar, Muhammad A. Alam|arXiv (Cornell University)|Mar 19, 2013

Photovoltaic System Optimization Techniques30 references3 citations

TL;DR

This paper proposes a novel geometrical design of thin film photovoltaic (TFPV) modules using radial and spiral cell arrangements to enhance shade tolerance and performance. By optimizing cell shape and orientation, the design prevents reverse breakdown in shaded cells, boosts power output under partial shading, and reduces sheet resistance losses—demonstrating improved resilience and efficiency compared to conventional rectangular layouts.

ABSTRACT

Partial shading in photovoltaic modules is an important reliability and performance concern for all photovoltaic technologies. In this paper, we show how cell geometry can be used as a design variable for improved performance and resilience towards partial shading in monolithic thin film photovoltaic (TFPV) modules. We use circuit simulations to illustrate the geometrical aspects of partial shading in typical TFPV modules with rectangular cells, and formulate rules for shade tolerant design. We show that the problem of partial shading can be overcome by modifying the cell shape and orientation, while preserving the module shape and output characteristics. We discuss two geometrical designs with cells arranged in radial and spiral patterns, which (a) prevent the reverse breakdown of partially shaded cells, (b) improve the overall power output under partial shading, and (c) in case of spiral design, improve the module efficiency by reducing sheet resistance losses. We compare these designs quantitatively using realistic parameters, and discuss the practical approaches to their implementation.

Motivation & Objective

• To address the critical challenge of partial shading in thin film photovoltaic (TFPV) modules, which degrades performance and reliability.
• To investigate how cell geometry—specifically shape and orientation—can be leveraged as a design parameter to improve resilience under partial shading.
• To develop and evaluate alternative geometrical layouts (radial and spiral) that maintain module form factor while enhancing electrical performance.
• To quantify improvements in power output and efficiency under partial shading conditions using circuit simulations with realistic parameters.

Proposed method

• Conduct circuit simulations to analyze the electrical behavior of conventional rectangular TFPV modules under partial shading conditions.
• Formulate design rules for shade tolerance based on current flow and voltage distribution in partially shaded cells.
• Propose two alternative geometrical configurations: radial and spiral arrangements of cells within the module.
• Optimize cell shape and orientation to minimize reverse current and voltage stress on shaded cells.
• Compare the performance of radial and spiral designs against standard rectangular layouts using realistic module parameters.
• Evaluate the impact of reduced sheet resistance losses in the spiral design on overall module efficiency.

Experimental results

Research questions

• RQ1 How does cell geometry influence the susceptibility of TFPV modules to reverse breakdown under partial shading?
• RQ2 To what extent can radial and spiral cell arrangements improve power output compared to conventional rectangular layouts under partial shading?
• RQ3 Can non-rectangular cell geometries maintain the same module shape and output characteristics while enhancing performance?
• RQ4 How do sheet resistance losses affect overall module efficiency, and can spiral design mitigate this?
• RQ5 What are the practical implementation challenges and benefits of adopting radial and spiral cell layouts in TFPV modules?

Key findings

• The radial and spiral cell designs prevent reverse breakdown in partially shaded cells by distributing current more evenly and reducing voltage stress.
• The spiral design reduces sheet resistance losses, leading to improved module efficiency compared to conventional rectangular layouts.
• Both alternative geometries significantly enhance power output under partial shading conditions, outperforming standard rectangular modules.
• Circuit simulations confirm that optimized cell geometry can maintain desired module output characteristics while improving resilience.
• The proposed designs offer a viable pathway to enhance reliability and performance of TFPV modules without altering the overall module form factor.
• Quantitative comparisons using realistic parameters demonstrate measurable gains in performance and shade tolerance, validating the design approach.