Small area high voltage photovoltaic module for high tolerance to partial shading

Abstract

The urban application of photovoltaics is necessary to achieve carbon-free electricity production. However, the serial connections within modules cause problems under partial shading conditions, which is inevitable in urban applications. Therefore, a partial shading-tolerance photovoltaic module is needed. This research introduces the small-area-high-voltage (SAHiV) module with rectangle and triangle shapes for high partial shading tolerance and compares its performance with conventional and shingled modules. We tested it with discrete and continuous shading shape groups to represent unpredictable shading by simulations using LTspice with Monte Carlo simulation combined with latin hypercube sampling that were validated by comparison with experimental results. The SAHiV triangle module exhibited the best partial shading tolerance under most scenarios. Both types of SAHiV modules (rectangular and triangular) were robust against all types of shading patterns and angles, as indicated by their stable shading-tolerance values. These modules are thus suitable for use in urban areas.

Keywords: Applied physics; Devices.

Graphical abstract

Figure 1

Main concept of small-area-high-voltage-photovoltaic module (A) Shading scenarios in an urban environment. In urban scenarios, shading cannot be predicted because the shape of the shadow will always change following the sun’s movement and because there are shadows of birds, leaves, and dust. (B) Cell shape used in the present research. This research included four types of cells; conventional cells measuring 60 mm × 60 mm are divided horizontally into shingled cells (15 mm × 60 mm). The conventional cell is divided into 12 with a rectangular shape, resulting in the SAHiV cell (15 mm × 20 mm), and with a triangular shape, resulting in the SAHiV triangle cell (30 mm × 20 mm). (C) Power output from conventional, shingled, and SAHiV modules under partial-shading conditions.

Figure 2

Module layout and shading scenarios (A) Module layout used in the present research. (B) The shading shape scenarios in the present research: a rectangle and two circles are used for discrete shading; a diagonal line with a 30° angle and a diagonal line with a random angle are used for continuous shading. (C) Difference between standard random sampling and Latin hypercube sampling (LHS). In LHS, numbers are chosen randomly by considering the multidimensional distribution. (D) How $P_{\mathrm{a}\mathrm{n}}$ is calculated. The blue dot is the relative power generated under the shadow, and the red point is the power generated under ideal conditions.

Figure 3

Validation of simulation by experiments (A) Mini module layout used in the experiment to verify the simulation results. (B) Example of shading scenarios used in the experiment. This scenario has rectangular and diagonal shading scenarios. (C) Comparison of the experiment and simulation results. The left graph shows the results for the rectangle scenario, and the right graph shows the results for the diagonal scenario.

Figure 4

Robustness and results of simulation (A) Robustness of the system. Testing is done by performing simulations ranging from 10 to 2500 scenarios. (B) Area graphs of shading with a rectangle, two circles, a diagonal line with a 30° angle, and a diagonal line with a random angle. Purple, blue, red, and green graphs represent the results for the conventional module, shingled module, SAHiV module, and SAHiV triangle module, respectively. Each point in the graph represents one shading scenario. (C) Graph of the $P_{\mathrm{a}\mathrm{n}}$ values. The left graph shows the results for the discrete shading group, and the right graph shows the results for the continuous shading group.

Figure 5

Results for shallow shadowing and heavy shadowing (A) The differences in shading scenarios of shallow shadowing (0–50%) and heavy shadowing (50–100%). (B) Results corresponding to shallow shadowing (0–50%). The left graph shows the results for the discrete shading group, and the right graph shows the results for the continuous shading group. (C) Results corresponding to heavy shadowing (50–100%). The left graph shows the results for the discrete shading group, and the right graph shows the results for the continuous shading group.

Figure 6

Power shading pattern in diagonal shading shade (A) Power shading pattern in the shingled module. The shingled module has horizontal patterns for which the shading shape and normalized power are shown on the right side. (B) Power shading pattern in the SAHiV module. The SAHiV module has a vertical pattern for which the shading shape and normalized power are shown on the right side.