L R AS Published on Monday 30 August 2021 - n° 371 - Categories:panels, evolution-stat
The life of panels as seen by the International Energy Agency
The International Energy Agency (IAE) looks at the lifetime of panels
The International Energy Agency (IAE) has studied the lifetime of photovoltaic panels. It points out that the degradation and the total lifetime
This has a direct influence on the electricity produced and thus the cash flow, which determines the profitability of a solar power plant.
The lifetimes and degradation rates are average values derived from evaluations. They are not derived from the components of the equipment, the quality of the installations, or the climatic conditions. The expected power output is derived from linear degradation rates that do not correspond to the degradation process in the field, which is generally non-linear.
The IEA study provides empirical modelling of degradation and lifetime prediction of PV panels, as it is the main components of PV systems that are subject to degradation effects. For other components, no comparable scientific data is available.
It tries to clarify the different terms as they are not used consistently by the industry or researchers. This is especially the case for the term "end of life" for which no generally applicable definition can be given for all situations. However, the definition is crucial for the calculated lifetime, the efficiency and all associated parameters, and thus the LCOE. In addition, climatic factors play a major role in the degradation and are specific to the location of the installations
The lifetime depends on different climatic stress factors. A distinction must be made between macro-climatic factors that affect the panels and the location of the material. There are data or maps for climatic regions. And micro-climatic factors: these identify the parameters that are relevant for the degradation processes and thus also for the mathematical models dealing with panel degradation and service life prediction. It takes into account the temperature and humidity which have an effect on the lifetime and the degradation prospect.
Once these factors are determined, the study models the degradation. This results in very different approaches to empirical modelling of lifetime performance prediction and product lifetime such as empirical statistical modelling of PV panels and empirical physical modelling. They use analytical or numerical forms to represent the fundamental physics and chemistry of the phenomena.
Another phase of the study focuses on specific panel degradations such as backsheet or cell cracking or electrochemical corrosion. Polymeric materials are known to be sensitive to degradation effects caused by typical climatic stress factors such as high temperature, humidity and UV radiation.
This is where performance degradation models can be addressed. They are basic models for predicting panel degradation over time for specific types and locations.
The latest scientific work shows that lifetime and degradation models of photovoltaic panels are particularly useful if they combine different modelling approaches and include the most relevant know-how and parameters for modelling degradation effects. Such models can differentiate the behaviour of different panel types and include the situation at different service locations. For some signs, it is also necessary to use multi-stage modelling approaches to obtain meaningful results.
Tecsol of1 August 2021
Editor's note: By making a general study of the factors influencing the end of life of panels, the IEA is obliged to generalise, to standardise the answers, and to water down its findings. The result is therefore disappointing