On June 1, the National Energy Administration and other departments issued the "Notice on Matters Related to Photovoltaic Power Generation in 2018" (because the date of the payment was May 31, the industry called '5·31 New Deal'), and proposed not to arrange for 2018 The scale of photovoltaic power plant construction, only about 10GW of distributed photovoltaic construction scale, to further reduce the subsidy intensity of photovoltaic power generation. This sudden new policy is like a basin of cold water, so that the photovoltaic industry once immersed in the crazy state gradually awake.
The pressure has given birth to power, and the release of the New Deal means that PV companies need to change their development direction and reduce the cost of photovoltaic power generation through more technological upgrades. At the same time, this is also an opportunity for enterprises to sink their minds to solve problems encountered in previous PV systems. In this paper, let us discuss the PID problem of PV modules.
PID (Potentian Induced Degradation) is a potential-induced attenuation phenomenon. It was first discovered by SunPower. It means that the component has long-term high voltage, so that there is leakage current between the glass and the package material. A large amount of charge accumulates on the surface of the battery. The deterioration of the effect, resulting in a fill factor (FF), short-circuit current (Isc), and open circuit voltage (Voc), makes the performance of the component lower than the design standard, and the power generation capacity also decreases. In 2010, NREL and Solon confirmed the component. What kind of technology is used for P-type crystalline silicon cells, the components have a risk of PID under negative bias.
There are many reasons for PID formation. The external environment may be due to the humid environment, and the surface of the component is contaminated by electricity, acidity, alkalinity, and ions with ions. It may also attenuate, resulting in leakage current. Systematic, The grounding mode of the inverter and the position of the components in the array determine whether the battery and components are positively biased or negatively biased. The actual operation of the power station and the research results show that: If the middle part of the column and the negative output of the inverter are When all the components are under negative bias, the PID phenomenon is closer to the output component. The PID phenomenon is not obvious when all components between the middle component and the positive output of the inverter are under positive bias. On the other hand, the cell sheet is uneven due to uneven doping; the increased sheet resistance used to optimize battery efficiency makes the cell sheet more susceptible to attenuation, resulting in a prone to PID effect.
According to the simulation of the PID effect of a component company's laboratory, the power variation and leakage current of the component are monitored. It is found that as the PID effect increases, the component power decreases sharply and the leakage current increases rapidly.
At present, the method of solving PID in the photovoltaic industry mainly adopts the method of optimizing the photovoltaic module battery material, using the sealing material with better sealing property and the negative electrode grounding of the thin film power generation component, and the practice of adding a PID repairing device.
The PID repair device is connected in parallel with the DC input of the inverter, applying a high voltage between the negative stage of the PV module and the ground, and supports outputting a fixed voltage and outputting an intelligently regulated voltage. At night, it can put the PV module in the daytime because of the negative electrode. The charge accumulated by the negative bias between the ground and the ground is released, and the PID-BOX will repair the battery components that are attenuated due to the PID effect.
In fact, the leakage current of the PV module affects the attenuation phenomenon. The real-time leakage current of the monitoring component can effectively reflect the attenuation level of the component and adjust it. However, the solution to detect the leakage current is very high. The component leakage current is very small, uA level; Secondly, the components are generally placed outdoors, where the lighting conditions are better, resulting in poor operating conditions, so higher requirements are imposed on current sensor manufacturers. Magtron is All Programamble PGA Sensor , a global leader in magneto-sensing SoCs, is committed to a new generation of smarter, high-power density and differentiated magneto-electric sensing system solutions. Driven by the industry's general trend of industrial IoT and sensor intelligence Under the innovative technology of Magtron's innovative technologies Quadcore, RCMU, iShunt, etc., magnetoelectric sensing, especially current sensor applications, are highly integrated and easy to use, while achieving high power density, and for the first time, high-speed software for sensors.
