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This work presents various models developed and implemented within the SOPHIA European project in order to thermally characterize PV modules in a rooftop BIPV configuration. Different approaches have been considered, including a linear model, lumped elements models and models that make use of commercial software solvers. The validation of the models performed by comparing the results of simulations with experimental data recorded on a test bench over an entire year is presented and discussed on a seasonal basis. The results have shown that all the models implemented allow achieving a good prediction of the PV modules back surface temperature, with the minimum value of the coefficient of determination R 2 around 95% on a yearly basis. Moreover, the influence of season weather conditions and of the incident solar irradiance magnitude on the accuracy of the considered thermal models is highlighted. The major result of the present study is represented by the fact that it has been possible to perform a better thermal characterization of the BIPV module by tuning some of the heat transfer coefficients, such as those relative to the effects of the wind velocity, and to the evaluation of sky temperature. [ABSTRACT FROM AUTHOR]

The inter-comparability of ageing of organic photovoltaic (OPV) technologies in dark is addressed. Four primary factors that affect the reproducibility of the ageing rate determination and inter-comparison are discussed: production/encapsulation of the samples, current–voltage ( IV ) characterization, testing conditions for ageing and lifetime determination from a decay curve. Results of inter-laboratory ageing studies of roll-to-roll and spin coated samples with correspondingly flexible plastic packaging and glass stored in dark conditions among 7 laboratories are presented. ISOS test conditions, proposed recently as guiding protocols for testing OPV stability, are applied in the study. The reproducibility of the performance versus the production and encapsulation techniques is firstly studied. The results reveal a significant improvement in the reproducibility when going from manual spin coating to roll-to-roll production. Furthermore, the reproducibility of current–voltage ( IV ) measurement and preconditioning (light soaking treatments) are addressed. Additionally, the inter-comparison of the degradation rates of the samples aged under three different dark test conditions (ambient, dry/heat, damp heat) reported by different groups are analyzed revealing a reasonable agreement. Finally, a logarithmic diagram for OPV lifetime associated with common time units is proposed that allows conveniently categorizing and intercomparing the stability performance of different samples aged under different test conditions. [ABSTRACT FROM AUTHOR]

Abstract: This study addresses the issue of poor intercomparability of measurements of organic photovoltaic (OPV) devices among different laboratories. We present a round robin performance testing of novel OPV devices among 16 laboratories, organized within the framework of European Research Infrastructure Project (SOPHIA) and European Energy Research Alliance (EERA). Three types of OPVs with different structures, dimensions and encapsulations are studied and compared with reference Si solar cells certified by accredited laboratories. The agreement of the measurements of these among different laboratories is analyzed by focusing on testing procedures, testing equipment and sample designs. A number of deviations and pitfalls are revealed and based on the analyses, a set of recommendations are suggested for improving the agreement among the measurements of such OPV technologies. [Copyright &y& Elsevier]

Abstract: Two different types of n-a-Si:H/p-c-Si heterostructure solar cells with intrinsic buffer layer, one type with and one type without back surface field (BSF), and one purely crystalline silicon solar cell have been irradiated with protons at 1.7MeV. For both types of heterojunctions and for the c-Si homojunction cells a similar dose been found for which degradation starts and also a similar decrease of the effective minority carrier diffusion length with increasing irradiation dose. For one type of heterojunction cells we observed a small increase of the collection efficiency in the blue part of the spectrum after irradiation what can be explained only by modifications of the interface between the crystalline silicon and the amorphous silicon or of the thin intrinsic a-Si:H layer. As a new tool for the evaluation of the solar cell degradation due to proton irradiation, electroluminescence measurements under forward bias have been used. The emission spectra confirms that for doses up to 5×1012 protons/cm2, silicon band-to-band recombination is the most important contribution to the light emission and the emission efficiency decreases monotonically with increasing proton dose. [Copyright &y& Elsevier]

Investigation of n–p heterojunction solar cells obtained by depositing a n-type thin silicon films either amorphous or microcrystalline on p-type c-Si is carried out. The study is focused on the improvement of the c-Si surface and emitter layer/c-Si substrate interface. The peculiarity is the use of SiF4-based plasmas for the in situ dry cleaning and passivation of the c-Si surface and for the PECVD deposition of the emitter layer that can be either amorphous (a-Si:H,F) or microcrystalline (μc-Si). The use of SiF4 instead of the conventional SiH4 results in a lower hydrogen content in the film and in a reduction of the interaction of the c-Si surface with hydrogen atoms. Furthermore, the dependence of the heterojunction solar cell photovoltaic parameters on the insertion of an intrinsic buffer layer between the n-type thin silicon layer and the p-type c-Si substrate is discussed. [Copyright &y& Elsevier]