An international research team has proposed a novel reconfiguration technique for PV arrays operating under fixed and moving shadows.
The proposed approach utilizes an asterisk sudoku method to determine the optimal way to connect the panels in the array, eliminating cluster shading, significantly reducing mismatch loss, and bypassing dependency.
“Asterisk sudoku is a variant of the popular logic-based puzzle that introduces a unique constraint: a set of nine cells arranged in an asterisk pattern must contain the digits 1 to 9 without repetition,” the team explained. “The asterisk cells interact with rows, columns, and subgrids, adding another layer of logical complexity. The distribution and number of clues affect the interconnection scheme, which is used to enhance the PV array’s electrical behavior, reducing mismatch losses and increasing power output.”
The scientists used the algorithm to reconfigure a 9 x 9 PV array divided into 3×3 blocks, arranged in a T-shaped pattern. Those grouped T-blocks were identified as shaded or not, and the algorithm rearranged them in a way that spreads them evenly in rows and columns. In practice, the different blocks are then rewired within the array.
The proposed method was then checked in MATLAB Simulink, with the 9×9 array being simulated with a panel capacity of 400.32 W. Key performance metrics, including I-V and P-V characteristics, were analyzed under four shading patterns, namely short wide (SW), long wide (LW), short narrow (SN), and long narrow (LN).
The optimal arrangement was checked under both fixed and moving shadows. Furthermore, it was also compared to other rearrangement methods, including the dominance square (DS), total cross-tied (TCT), killer sudoku (KSDK), and the chess knight.
Image: Hamad Bin Khalifa University, Renewable Energy, CC BY 4.0
“The proposed method showed significant improvement, achieving a maximum power gain of 1,339.74 W in SW and a 397.87 W increase in LW compared to the KSDK arrangement,” the academics stressed. “This approach redistributes shading effects, balancing row and column currents to minimize energy losses and improve efficiency. The method maintains a higher fill factor and stable power output, making it ideal for real-time PV array reconfiguration.”
In addition, the group validated its simulation results using an experimental setup, which was set up in Doha for two consecutive September days. Global horizontal irradiance (GHI) peaked at 900 W/m², while temperatures reached a maximum of 43 C. They used a 3×3 PV array, consisting of 240 W polycrystalline modules, and employed geotextile materials to replicate theoretical shading patterns.
The experimental validation confirmed the effectiveness of the new methodology in mitigating mismatch losses and maximizing energy yield under partial shading.
“Furthermore, its enhanced spatial redistribution of shaded modules effectively mitigates cluster shading effects, reducing mismatch losses without requiring additional hardware or complex controls,” the group concluded. “These results demonstrate that the asterisk sudoku-based T-swap method not only optimizes power output and efficiency under partial shading but also delivers superior annual energy yield and economic returns, confirming its robustness and scalability for dynamic PV array reconfiguration.”
Its findings were presented in “Performance analysis of a new PV array reconfiguration approach: Simulations and outdoor experiments under fixed and moving shadows,” published in Renewable Energy. The study was conducted by researchers from Qatar’s Hamad Bin Khalifa University and South Korea’s Pohang University of Science and Technology.
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