A voltage divider strategy for reducing the hot spot temperature in partially shaded solar panels

Abstract

Over-temperature occurring in silicon solar panels, subject to partial shadowing, are reduced by means of a series connected voltage divider which sustains part of the reverse voltage developing across the shaded solar cells. The circuit is based on a power MOSFET which is driven by the output voltage of the solar panel. When the solar panel is uniformly illuminated the MOSFET is in the ON state and does not affect the operation of the module, while, when the solar panel is partially shaded, and the output voltage decreases, the MOSFET enters in the pinch-off operation mode, thus subtracting its voltage from the reverse voltage across the shaded cell. Experiments performed on a commercial solar panel showed one third of reduction of the reverse voltage across shaded solar cells, with a reduction of the hot spot temperature of about 25°C

Efek Partial Shading Terhadap Effisiensi yang Dihasilkan Oleh Solar Panel di Wilayah Karang Joang

“…Bahan semikonduktor yang digunakan pada panel surya untuk mengkonversi energi tersebut berupa silicon. Bahan tersebut terdiri atas dua buah lapisan yaitu lapisan bermuatan negatif (N) dan lapisan bermuatan positif (P) [8][10], seperti yang ditunjukkan pada Gambar 3.…”

Influence of Backtracking at Solar-Tracking Photovoltaic Power Plants for Generation and Protection

“…When a row of PV modules causes shading in the next row, the PV array is partially shaded, generating hotspots [12]. Hotspots are one of the main causes of accelerated aging and, sometimes, of irreversible damage to PV panels [15]. Also, partial shading makes it difficult to trace the maximum power point [16].…”

“…The current capacity at the PV cell depends of its short-circuit current. With the PV cell conducts a current level higher than its short-circuit current, this can cause damage [15].…”

Novel Current Sensor-less MPPT Algorithm for Solar Applications

“…Figure 2-3 shows the I-V and P-V curve of a solar panel which is uniformly exposed to the sunlight and it is assumed that there are no shaded spots on it. By drawing the constant power curves on the V-I graph, which are hyperbolic curves defined by V.I=Pm equation, it is shown that the MPP only happens on a single point highlighted in Figure 2-3 In addition, factors such as dust [27], cloudy sky [28], dirt or guano [29], and aging [30] can cause dark spots on the solar panel. Another similar scenario happens in a string of solar panels.…”