Tecnologie fotovoltaiche innovative per ridurre il costo dell'elettricità

Il costo per Watt delle celle solari si è ridotto così velocemente negli anni, che i costi di fabbricazione dei moduli fotovoltaici incidono poco sui costi totali di un impianto fotovoltaico: sono i costi di installazione e gestione e quelli dei materiali di base che determinano principalmente il costo per la produzione di elettricità. L'aumento di efficienza e l'energia prodotta dall'impianto costituiscono oggi le leve più importanti per la riduzione dei costi complessivi. La tecnologia dei moduli fotovoltaici si è evoluta nella direzione di massimizzare l'efficienza di conversione e l'energia prodotta in media da un impianto fotovoltaico cercando di ottimizzare la raccolta di luce e ridurre le perdite. In questo lavoro discuteremo dello stato dell'arte della tecnologia fotovoltaica per impiego terrestre che è in gran parte basata sul silicio, il secondo elemento più abbondante sulla terra, e delle prospettive di sviluppo futuro che puntano a superare i limiti imposti dalle caratteristiche dei materiali

Durability and Performance of Encapsulant Films for Bifacial Heterojunction Photovoltaic Modules

Energy recovery from renewable sources is a very attractive, and sometimes, challenging issue. To recover solar energy, the production of photovoltaic (PV) modules becomes a prosperous industrial certainty. An important material in PV modules production and correct functioning is the encapsulant material and it must have a good performance and durability. In this work, accurate characterizations of performance and durability, in terms of photo- and thermo-oxidation resistance, of encapsulants based on PolyEthylene Vinyl Acetate (EVA) and PolyOlefin Elastomer (POE), containing appropriate additives, before (pre-) and after (post-) lamination process have been carried out. To simulate industrial lamination processing conditions, both EVApre-lam and POEpre-lam sheets have been subjected to prolonged thermal treatment upon high pressure. To carry out an accurate characterization, differential scanning calorimetry, rheological and mechanical analysis, FTIR and UV-visible spectroscopy analyses have been performed on pre- and post-laminated EVA and POE. The durability, in terms of photo- and thermo-oxidation resistance, of pre-laminated and post-laminated EVA and POE sheets has been evaluated upon UVB exposure and prolonged thermal treatment, and the progress of degradation has been monitored by spectroscopy analysis. All obtained results agree that the lamination process has a beneficial effect on 3D-structuration of both EVA and POE sheets, and after lamination, the POE shows enhanced rigidity and appropriate ductility. Finally, although both EVA and POE can be considered good candidates as encapsulants for bifacial PV modules, it seems that the POE sheets show a better resistance to oxidation than the EVA sheets

Influence of defects on silicon heterojunction solar cell efficiency: Physical model and comparison with data

We have studied the influence of defects on silicon heterojunction solar cell efficiency by a method based on the comparison of electroluminescence (EL) image data with a finite element circuit model of solar cell efficiency. For this purpose, a general curve that relates the solar cell efficiency to a parameter representative of the defect strength, i.e., the loss of VOC, ∆VOC, from EL maps is obtained, and it is shown that the efficiency can be predicted with a good degree of confidence

Role of patient and tumor characteristics in sentinel lymph node metastasis in patients with luminal early breast cancer: an observational study

Predicting the risk of sentinel lymph node (SLN) metastasis is important for clinical decision-making in the setting of early breast cancer (EBC). This study is aimed to identify tumor and patient characteristics that influenced the SLN metastatic involvement, with a focus on luminal subtypes. An observational study including women treated for EBC from 2005 to 2013 was conducted. Regression analyses were used to assess the association between SLN metastasis and age, menopausal status, tumor size, histological grading, presence of extensive “in situ” carcinoma components, lymphovascular invasion (LVI), and expression of Ki-67, hormone receptors, and HER2. Of 345 women, 84 (24.3 %) had at least one SLN metastasis; 63.1 % were macrometastases. Among all patients, 31.6 % exhibited LVI. In univariate analyses, tumor size, histological grade, and LVI were associated with SLN metastasis. The multivariate model confirmed only the association between LVI and SLN status (OR 3.27, 95 % CI 1.85–5.68; p < 0.0001). Luminal subtypes were detected in 86.1 % of women. In this subgroup, the multivariate model confirmed a significant relationship between LVI and SLN status (OR 3.47, 95 % CI 1.90–6.33; p < 0.0001). Since a proper histopathological assessment of LVI is not possible prior to surgery, this factor cannot be used to guide decisions on performing SLN biopsies. Nevertheless, when a SLN biopsy is refused or contraindicated, an LVI assessment on an excisional biopsy of the tumor could facilitate prognosis determination and treatment management

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p &lt; 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Tecnologie fotovoltaiche innovative per ridurre il costo dell'elettricità

Il costo per Watt delle celle solari si è ridotto così velocemente negli anni, che i costi di fabbricazione dei moduli fotovoltaici incidono poco sui costi totali di un impianto fotovoltaico: sono i costi di installazione e gestione e quelli dei materiali di base che determinano principalmente il costo per la produzione di elettricità. L'aumento di efficienza e l'energia prodotta dall'impianto costituiscono oggi le leve più importanti per la riduzione dei costi complessivi. La tecnologia dei moduli fotovoltaici si è evoluta nella direzione di massimizzare l'efficienza di conversione e l'energia prodotta in media da un impianto fotovoltaico cercando di ottimizzare la raccolta di luce e ridurre le perdite. In questo lavoro discuteremo dello stato dell'arte della tecnologia fotovoltaica per impiego terrestre che è in gran parte basata sul silicio, il secondo elemento più abbondante sulla terra, e delle prospettive di sviluppo futuro che puntano a superare i limiti imposti dalle caratteristiche dei materiali

On the Improvement of SIMS Technique by the Use of MCs+\bf MCs^+ Molecular Ions

The SIMS $\rm MCs^+$ method, consisting of detecting the molecular ions formed by the element of interest M and $\rm Cs^+$ ion, emitted under $\rm Cs^+$ bombardment is discussed in this work. A strong reduction of matrix effects has been observed in all the investigated samples. Moreover linear calibration curves can been obtained with good accuracies by plotting the relative matrix concentrations against the corresponding signal intensity ratios. A comparison with XPS results obtained from the analysis of a Fe on Zr on $\rm SiO_2$ structure has been also reported. In addition good depth resolution and near surface pre-equilibrium region reduction have been observed on $\rm MCs^+$ profiles

Reversible Efficiency Variation of Tandem Amorphous/Microcrystalline Si Photovoltaic Modules in Outdoor Operation

The Staebler-Wronski effect in amorphous silicon based photovoltaic devices is responsible for degradation of their power conversion efficiency, within approximately the first one thousand hours of light soaking. Several experimental studies led to highlight the performance instability phenomena for the mentioned devices, underling that recovery and improvement of such performance are observable, by subjecting such devices (both of single-junction and tandem types) to DC reverse bias stresses under illumination, or to operation in the Maximum Power Point (MPP) under variable conditions of temperature and illumination. In this work, we present and discuss the results of novel recent outdoor tests on stabilized specimens (i.e., exposed to 1000 h extended light soaking, before our tests) of tandem amorphous/microcrystalline Si (a-Si/µc-Si) photovoltaic (PV) minimodules operating in their MPP, by analyzing the causes of the performance instability effects, systematically observed on a daily scale. During the mentioned tests, we have monitored the solar cell operating temperature and the incident solar spectrum at various times in different days to verify the effect of cell temperature and solar spectrum changes on the cell performances. The experimental results show a clear correlation between performance improvements of the photovoltaic modules and their thermal history during the outdoor tests, proving the interplay between defect build-up at a lower temperature and defect annealing at a higher temperature, taking place in the solar cells operated in MPP during conventional outdoor operation.</jats:p