Partial Shading Effects on Photovoltaic Systems

Partial shading occurs when an obstruction such as foliage, adjacent buildings or soiling casts uneven irradiance across a photovoltaic (PV) module or array. This phenomenon disrupts the uniform current flow through series-connected cells, causing mismatch losses and the formation of local hot spots. Under partial shading, the current–voltage (I–V) characteristic of a PV string develops multiple peaks, complicating maximum power point tracking and reducing overall energy yield. The severity of the performance penalty depends on the shading pattern, the interconnection topology of cells, and the presence of mitigation measures such as bypass diodes or module‐level power electronics. Research has explored both passive solutions—optimised diode placement, cell layout and cut‐cell techniques—and active methods, including dynamic reconfiguration of cell strings and intelligent control algorithms, to restore the balance of currents and recover lost power. Addressing partial shading is vital for reliable operation of rooftop installations, bifacial panels, building‐integrated PV and dense urban arrays where intermittent shade is unavoidable.

Research from Nature Portfolio

A full-scale prototype of a series-parallel PV module, comprising six reconfigurable blocks, was tested outdoors over several months under varying illumination. Compared with a reference module with fixed interconnections and conventional bypass diodes, the reconfigurable design yielded over 10% additional energy under partial shading. Under uniform illumination the dynamic architecture incurred a minor 2% penalty due to switching losses, but a refined reconfiguration algorithm was shown to narrow the voltage–current operating range and streamline module‐level power conversion. This work demonstrates that adaptive interconnection schemes can significantly enhance shading tolerance without major hardware modifications.

Partial Shading Effects on Photovoltaic Systems publication trend

The graph below shows the total number of articles in partial shading effects on photovoltaic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Partial shading: Uneven solar irradiance on a PV module or array causing current mismatch and reduced power output.

Bypass diode: Semiconductor device that provides an alternate current path around shaded cells to prevent hot spots and minimise power loss.

Reconfigurable module: Photovoltaic architecture with adjustable electrical interconnections to optimise performance under variable shading.

Cell mismatch: Variation in current-producing capability among cells due to non-uniform illumination or manufacturing tolerances.

Maximum power point (MPP): Operating voltage and current at which a PV system delivers its highest power output.

Hot spot: Localised overheating in a PV cell or module caused by reverse‐biased shaded cells dissipating energy as heat.

References

1. Impact of Partial Shading on the P-V Characteristics and the Maximum Power of a Photovoltaic String. Energies (2018).
2. Electrical performance of a fully reconfigurable series-parallel photovoltaic module. Nature Communications (2023).
3. A Comprehensive Review on Bypass Diode Application on Photovoltaic Modules. Energies (2020).
4. Simulation study of the electrical yield of various PV module topologies in partially shaded urban scenarios. Solar Energy (2021).
5. A Comprehensive Study of Module Layouts for Silicon Solar Cells Under Partial Shading. IEEE Journal of Photovoltaics (2022).