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An international group of researchers has developed an electronic device that effectively mitigates hot spots in photovoltaic modules. It uses two current comparators, two NPN transistors and a current mirror circuit to identify anomalies in current flow and allow precise control of input and output current through a purely resistive element.
An international team of researchers has manufactured an electronic circuit capable of reducing the formation of hot spots and increasing the energy performance of photovoltaic modules.
The proposed system uses two current comparators, two NPN transistors and a current mirror circuit. These devices are integrated using an automatic switching mechanism that scientists say eliminates the need for conventional bypass diodes by providing a dynamic response to fluctuating thermal conditions.
In the proposed system configuration, the current comparator identifies anomalies in current flow indicative of potential hot spots, while the current mirror circuit reacts to these anomalies by calibrating the current flow. “This design allows precise control of the input and output current through a purely resistive element, which favors a more stable and efficient operating environment for the photovoltaic module,” the researchers explain.
The current comparator works in two stages. First, it evaluates the output currents of the first and second PV substrings. It then juxtaposes the differential current obtained from this evaluation with the last PV substring. The researchers describe the last step as the critical step that ensures a homogeneous current in all substrings, which they say prevents the appearance of hot spots.
The electronic circuit can work by obtaining electricity from the solar modules themselves and, according to its creators, its energy consumption is minimal.
Through a series of validation tests in which the circuit was exposed to high current loads, the research group verified that it could ensure sufficient thermal stability within safe operating limits. “This strong performance indicates the circuits suitability for a wide range of photovoltaic installations, from small-scale residential to large-scale industrial applications,” he explained, noting that the device “significantly” reduced hot spot temperatures from the “dangerous” threshold of 55 ºC.
The scientists also found that use of the system can lead to increased energy yields, ranging from 3% to 5.35%, in solar panels affected by adjacent and non-adjacent hot spots. However, they also warned that although the system guarantees a more uniform distribution of current, it is not capable of correcting energy losses at the point of defects.
“Although the circuit significantly reduced the temperatures of the hot spots, bringing them closer to those of healthy cells, it did not completely normalize them,” they concluded, alluding to the current limitations of the device.
The study is described in the article “ Photovoltaic hotspots: a mitigation technique and its thermal cycle,” recently published in Optik . The research team consisted of scientists from York University (UK), the US Department of Energys Sandia National Laboratories, and the University of Naples Federico II (Italy). |
