Fabien Delaleux

Investigation of damp heat effects on glass properties for photovoltaic applications

ABSTRACT 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.

Evolution of the Efficiency of a Photovoltaic/Supercapcitor System with Aging

The evolution of the optimization of photovoltaic/supercapacitor system according to its age is inquired. The system is modeled by an accurate equivalent circuit. The durations and energies of charge/discharge cycles are calculated for a 10 year use. The temporal and energy efficiencies are then deduced according to time, and optimal values are hence extracted. Results show that the optimal efficiencies can be kept constant over time at a value around 90% for the energy. However, the amount of energy stored and released by the supercapacitors is reduced over the years and the response time becomes shorter. So, the behavior of the system is modified with aging regarding its initial nominal functioning. This has to be considered to know the real profitability of the system.

A self - method for solving the problem of LWIR spectral band of camera for quantitative thermography

In a previous work, we succeeded in connecting normal LWIR apparent emissivity to the spectral one of an aluminium nitride ceramic plate. We showed a good agreement with the assumption of spectral bandwidth of the used IR system. Our aim in this paper is to justify the considered spectral band [7.5μm, 12μm]. Hence we have developed an analyzer of IR system. The analyzer proceeds by comparing thermosignals with integrated blackbody radiance and adapts spectral bandwidth in order to minimize the dispersion from linearity of the characteristic thermosignals / integrated radiance over a temperature range of the IR system. The capacities of the analyzer are tested for 6 commercial cameras. Each of these systems exhibits a similar formatting process implemented during the thermogram recording. The effective spectral bandwidth exhibits plausible values. It varies significantly from one model to the other and the residual non-linearity is connected to the NETD of the IR system. Applied to the same system which served to characterize the apparent emissivity, the analyzer permits to quantify the effective spectral band. We obtain an excellent agreement between the classical model of apparent emissivity and measurement, both in terms of accuracy and in terms of temperature dependence. The absolute error is 0.005 for emissivity and the temperature coefficient is less than 6 10 °C within the temperature range [40°C, 130°C].