Damp heat test was performed on soda-lime glass to characterise functional properties of glass in photovoltaic applications and define the ageing mechanism. In addition to the optical property measurements, SEM-EDX, XPS and FTIR analyses were carried out. The damp heat exposed samples presented an increased transmittance in UV, visible and near-IR ranges namely within (1900–2100 nm). The results were explained by hydration of glass network with heat. An ageing mechanism based on glass corrosion theories is discussed. Molecular water adsorption involves a leaching process of network modifier cations and especially sodium ions. Hydrolysis also occurs in silica network by reacting free molecular water. This phenomenon enhances concentration of hydroxyl groups in glass highlighted by FTIR measurements and promotes formation of silanol groups. A tin side dependence on sodium leaching which acts as a passivating barrier for ionic transport is highlighted which may be taken into consideration for photovoltaic module design.

The storage of photovoltaic energy by supercapacitors is studied by using two approaches. An overview on the integration of supercapacitors in solar energy conversion systems is previously provided. First, a realized experimental setup of charge/discharge of supercapacitors fed by a photovoltaic array has been operated with fine data acquisition. The second approach consists in simulating photovoltaic energy storage by supercapacitors with a faithful and accessible model composed of solar irradiance evaluation, equivalent electrical circuit for photovoltaic conversion, and a multibranch circuit for supercapacitor. Both the experimental and calculated results are confronted, and an error of 1% on the stored energy is found with a correction largely within ±10% of the transmission line capacitance according to temperature.

The aging of photovoltaic modules results inevitably in a decrease of their efficiency all through their lifetime utilization. An approach to simulate the evolution of electrical characteristics of a photovoltaic module with aging is presented. The photovoltaic module is modeled by an equivalent electrical circuit whose components have time-dependent characteristics determined under accelerated tests. By entering sun irradiance and temperature, I–V and P–V curves as well as efficiency evolution can be simulated over years assuming equivalent time. The methodology is applied for the case of a monocrystalline photovoltaic module modeled by a one-diode circuit and aging laws are determined with experimental results of damp heat (DH) tests 85 °C/85% RH performed by Hulkoff (2009, “Usage of Highly Accelerated Stress Test (HAST) in Solar Module Aging Procedures,” M.S. thesis, Chalmers University of Technology, Göteborg, Sweden). A power degradation rate of 0.53%/yr is found. A parametric study shows that the rundown of optical transmittance of the upper layers with aging has the most important impact by reducing the initial efficiency by 11.5% over a 25-year exposure contrary to electrical degradations which cause a decrease of 1.85% of the initial efficiency.

The performance of the photovoltaic power plant of Sourdun in France is studied for a period of seven years using the IEC 61724 standard. The 4.5 MWp photovoltaic installation is located in a warm temperate climate area and includes polycrystalline photovoltaic panels. The analysis of the collected data from the monitoring system reveals an average degradation rate of the power plant of 0.209%/year. The found degradation rate is in agreement with other values obtained for different power plants using the same method and having close characteristics. The degradation value is determined from the slope of the annual change in the performance ratio corrected regarding the temperature. The yearly performance ratio varying between 84.12% and 90.54% is higher in spring and lower in the summer with an average value of 87.18%. The average yearly evolutions of the reference yield and of the final yield are 3.92 h and 3.33 h respectively.

The lifetime estimation of photovoltaic (PV) systems is an important consideration in their life cycle. This paper presents a multi-level methodology to estimate the availability and the lifetime of a PV system using stochastic Petri networks and taking into account the time distribution to failure and to repair. The following components – module, wires, and inverter – are modeled with a Petri network. The evolution of the MTBF, availability, and outages over a 30-year period is simulated for different series/parallel configurations of connected PV modules. Findings are in agreement with reported experimental results, namely the evolution of the availability which tends to be near 96% for long times. Numerical results show that the highest MTBF is 3.2 years and the lowest outage is of 11.84 days/year, which are both obtained for the string configuration. The approach is interesting for the dimensioning of a PV plant or an installation.