Huawei Smart PV Solution: The Perfect Anti-PID Solution
Potential induced degradation (PID) is a phenomenon that has recently become a major concern in the photovoltaic industry. PID impacts the ions of a solar cell and results in the degradation of the output of that cell.
After PV modules are used on a large scale for a period of time, the power efficiency of the PV modules may be attenuated, which reduces the output power of the entire PV system. In some cases, power losses at the module level as high as 70% in the first 18 months. Starting on a module level, the losses can progress rapidly and affect the performance of an entire system.
The occurrence of PID depends primarily on the electrical configuration of the system but other parameters such as system voltage, temperature, humidity and irradiance are factors contributing to the occurrence of PID. Researches have shown that the high voltage between the circuit in the crystalline silicon PV modules and the grounding metal frame results in potential performance attenuation of the PV modules, which is called potential induced degradation (PID) in the industry.
PID in the crystalline silicon solar cell was first found in 2005. In 2008, Evergreen reported that PID occurs in the P-type solar cell module in the case of a high negative bias.
Traditional Anti-PID Solution: A Risk to Life and Property
To prevent PID effects, a traditional solution is that the input PV- is grounded via a fuse or breaker. Due to this, a high voltage builds up between PV+ and PE with the usual fuse rating being above 5A. If someone touches PV+ accidentally, the large current may cause human injury or even death. Moreover, this cannot be avoided by any additional device. In addition to this, the grounding fault of the PV+ or cable generates faulty current or arc by using grounding wires, which gives rise to a potential fire hazard.
Huawei Anti PID Solution: Safe and Secure
So how do Huawei inverters offer a unique and safe solution to the PID problem? First of all, Huawei Smart PV Solution is a floating ground system on the LV side and PV- isn’t connected to the ground. This Huawei Smart PV Solution integrated with anti-PID modules offer the ideal anti-PID solution, neutralizing the above risks. Let’s see how.
In order to prevent the PID issue, Huawei applies advanced anti-PID module with anti-PID kits developed by Huawei. When the inverters are under-operating, the neutral point voltage of inverter BUS capacitance, the neutral voltage of the string and voltage from N side of AC to the ground are the same. When voltage from N side of AC to the ground is raised, the neutral voltage of the string is also equally raised. So Huawei anti-PID module makes sure that the voltage between PV- and ground beyond 0 V efficiently prevent PID effects. Furthermore, because the PV- of DC side doesn’t connect to ground, there is no risk when someone touches the modules.
Also, Huawei string inverter has residual current detecting circuit that can detect leakage current bigger than 30 mA, and can cut the circuit immediately to ensure human safety.
The success of the solution can be seen from a real-life case study. Figures 1 and 2 show the inverter's real-time voltage to ground in the 50 MW PV plant in Telangana, India, manifesting the exceptional performance of the Huawei Anti-PID solution.
Huawei Anti-PID Solution: A Global Success
Today, Huawei anti-PID technology has been accepted globally and is used by leading developers across continents. The Huawei Smart PV Solution is being widely used in many projects in Europe, US, China, India, East South Asia, etc. and is fast becoming the most preferred choice as a perfect anti-PID solution.