by Davy Verheyden, Managing Director at Pidbull (Edison Energy Group)
As solar power is increasingly popular and operators of solar parks in particular seek maximum returns, the concerns about PID are growing. PID (Potential Induced Degradation) is a fact of life in all photovoltaic solar systems. It leads to reduced efficiency of systems, in addition to the performance reduction through regular degradation processes, such as aging or impact from weather conditions and the like.
One of the problems of PID is that it is difficult to accurately determine to which extent this specific degradation process creates efficiency loss. The efficiency of a solar cell is dependent on numerous factors, such as solar irradiation and the location and period in which a measurement takes place. Nevertheless, PID can lead to a significant loss of efficiency. This can start with 2.5 percent and increase up to thirty percent. It is obvious that this is a poor business case for large-scale solar power generation. In addition, PID also occurs in relatively young plants.
How does PID actually occur? A solar panel consists of individual photovoltaic cells. Each of these cells generates electricity from the collected sunlight. Technically spoken, the combination of two semiconductor materials exchange charges, resulting in an internal electric field. The incident sunlight dislodges electrons. Subsequently, these electrons flow along the contacts and generate electricity. In PID, this process is disrupted by the presence of electrical charge carriers. These electric charges have a strong negative impact on the performance of the photovoltaic cell. As a result, the solar cell generates less electricity than without the PID effect. PID occurs primarily in very hot and humid conditions with high voltage systems.
Technologies have come to market that reduce PID. They attract great interest, because tests show that these technologies provide a major boost to the efficiency of solar parks. After examining the PID phenomenon, in cooperation with the independent European research center IMEC, a proprietary technology was developed and patented: Pidbull. Tests by Edison Energy of this self-developed solution showed that average and underperforming inverters achieved a performance improvement of twenty percent. Furthermore, the best performing inverters were able to show an improvement of over ten percent. Also, the worst-performing inverters achieved an improvement of thirty percent.
The development of these technologies is good news for the renewable energy industry, as the return on investment is quicker and energy parks have a longer lifecycle, as well as a higher return.