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The TISO‐10‐kW plant, installed in Lugano (Switzerland) in 1982, is the first grid‐connected PV plant in Europe. In a joint publication (part 1), we presented the results of the electrical characterization performed in 2017—after 35 years of operation—of the 288 Arco Solar modules constituting the plant. Power degradation rates were different among modules and two groups could clearly be distinguished: group 1, with a remarkably low mean degradation rate of −0.2% per year, and group 2, with a mean degradation of −0.69% per year. After 35 in a temperate climate, approximately 70% of the modules (considering a ±3% measurement uncertainty) still exhibit a performance higher than 80% of their initial value. In this paper, when possible, we attempt at correlating module performance losses to specific failure mechanisms. For this sake, an extensive characterization of the modules was performed using visual inspection, IV curve measurements, electroluminescence, and infrared imaging. We remarkably find that module degradation rates are highly correlated to the aging pattern of the encapsulants used in module manufacturing. In particular, a specific formulation of the encapsulant (PVB), which was used only in a minority of the modules (approximately 10%), leads to degradation rates of −0.2% per year, which corresponds to a loss in performance below 10% over 35 years. Potential safety threats are also investigated, by measuring the frame continuity, the functionality of the bypass diodes, and the module insulation. Finally, we discuss how the analysis of a 35‐year‐old PV module technology could benefit the industry in order to target PV module lifetimes of 40+ years.

The TISO‐10‐kW solar plant, connected to the grid in 1982, is the oldest installation of this kind in Europe. Its history is well documented, and the full set of modules has been tested indoors at regular intervals over the years. After 35 years of operation, we observe an increase in the degradation rates and that the distributions of modules' performances are drastically changing compared with previous years. Two groups of modules can be observed: (a) group 1: 21.5% of the modules show a very modest degradation, described by a Gaussian distribution with mean yearly power degradation of only −0.2%/y. (b) Group 2: 72.9% of the modules form a negatively skewed distribution with a long tail described by mode (−0.54%/y), median (−0.62%/y), and mean (−0.69%/y) values. In earlier years, decreases in performances could strongly be correlated to losses in fill factor (FF). After 35 years, the situation changes and, for a subset of modules, losses in the current (Isc) are superimposed to losses in FF. The reasons for this will become clearer in part 2, where we will present results of a detailed visual inspection on the whole set of modules and will focus on safety aspect too. We conclude that, after 35 years of operation in a temperate climate, approximately 60% (~70% if considering a ± 3% measurement uncertainty) of the modules would still satisfy a warranty criteria that module manufacturers are presently considering to apply to the technology of tomorrow: 35 years of operation with a performance threshold set at 80% of the initial value.

In 2003 a fully-integrated photovoltaic (PV) plant composed by amorphous silicon PV modules was installed on top of a flat roof in Lugano (Southern Switzerland) – a site representative for most of continental Europe – and continuously monitored since. This work follows a previous study which analyzed the first 2 years of operation of the plant, ascribing most of the noticeable winter losses to reflection losses due the lower position of the sun in the sky. Other loss mechanisms were discussed only from a qualitative point of view. The energy production of this particular PV installation is in fact influenced by several combined phenomena such as Staebler–Wronski, spectral variations, temperature and optical losses effects. The present work aims to widen the analysis by discerning between these partly competitive effects and attempts to give a quantitative description of the influence which each single phenomenon has on the energy performance of the PV plant. For this purpose, single PV modules similar to those of the plant (triple-junction a-Si) were subjected to several indoor and outdoor tests. By means of indoor characterization we found that reflection losses become significant for angles of incidence larger than 50°. Repeated indoor and outdoor degradation–recovery cycles underlined the influence of annealing time and temperature on the recovery of the PV modules. In particular outdoor degradation tests showed that at our latitudes (46°N) the influence of the Staebler–Wronski effect on the output power of these devices is around 10% (±5% around an annual average value). The influence of the spectral effects on the current of amorphous silicon modules was assessed by means of outdoor IV characterization: the short circuit current decreases linearly with AM value at a slope between 4% and 8% per AM-unit depending on the technology under investigation. Combining these three effects with the effect of temperature the authors are able to perform a simulation of gains and losses of the a-Si modules which well approximates the energy performance of the CPT-Solar plant over a whole year.

In BIPV design (Building Integrated PV) with crystalline silicon (c-Si) solar cells, ventilation is important in order to keep cells as cool as possible. To allow good ventilation it is therefore generally preferable to mount the modules separated from the existing roof. In the case of sloped roofs, the modules are superimposed onto the existing roof and for flat roofs separated tilted mounting structures designed to withstand wind loads are used instead, but both are not real building integrations. In this paper we analyse the behaviour and the energy yield of a 15.36 kWp PV system based on flexible triple junction amorphous silicon modules laminated together with a single ply roofing system. The PV plant has been integrated on a flat roof of a professional school located south of Switzerland. A significant part of the data analysis is done in comparison with three small open-rack plants (reference plants) installed near the integrated plant. An important result was that the thermally insulated nearly horizontal modules showed temperatures higher than for modules mounted on an open-rack structure, especially for sunny days. This created higher power losses due to negative temperature coefficients. On the other hand, the higher temperature reached the level where the main degradation mechanism of a-Si modules could be reversed and better thermal annealing could be observed. This conclusion was arrived at after a direct performance comparison of the thermally insulated plant and the open-rack a-Si reference plant, which has the same module and orientation as the main plant. In order to better understand the thermally insulated nearly horizontal plant behaviour, we analysed and quantified the irradiation difference and optical losses with respect to a 20° tilted open-rack c-Si power plant. Optical losses for nearly horizontal modules were significant during the winter, partially affecting their low performance. As a main result, the final energy yield of the thermally insulated a-Si plant was almost comparable to a 20° tilted open-rack c-Si power plant, despite the lower irradiance and higher reflection losses with respect to the latter. Accordingly, compared to c-Si modules, the a-Si technology represents a better choice for thermal insulated BIPV.

We present a new tool for the measurement of the non-uniformity of a large-area pulsed solar simulator according to IEC 60904-9. We realized a prototype portable unit that can be controlled via a single USB port of a notebook. The system is composed by several photovoltaic cells and a series of custom designed electronic boards, allowing a high-speed multi-channel sampling of a single pulse. We describe the main components and the design solution, which is using readily available standard electronic and software components, allowing a possible industrialization of the system. Finally we present preliminary results of the prototype unit testing.

Performance testing of high-efficient, highly-capacitive c-Si modules with pulsed solar simulators requires particular carefulness in order to avoid measurement artifacts. These devices in fact usually require a steady-state solar simulator or pulse durations longer than 100 ms. The aim of this work was to validate an alternative method for the testing of highly capacitive c-Si modules using a 10-ms single pulse solar simulator. Our approach attempts to reconstruct a quasi steady-state IV curve of a highly-capacitive device during one single 10-ms flash by applying customized voltage profiles - in place of a conventional V ramp - to the terminals of the device under test. The most promising results were obtained by using V profiles which we name “dragon-back” (DB) profiles. When compared to the reference IV measurement (obtained by using a multi-flash approach), the dragon-back V profile method provides excellent results with differences in the estimation of Pmax below ±0.5% (as well as of Isc, Voc, and FF). For the testing of highly-capacitive devices the method is accurate, fast (two flashes - possibly one - required), and cost-effective.

Background Inside the spectrum of non-alcoholic fatty liver disease, simple fatty liver is generally thought of as being "non progressive", differently from non-alcoholic steatohepatitis, which increases in severity due to the presence of apoptosis/inflammation and fibrosis. The "benignity" of fatty liver is widely accepted but conceptually difficult to maintain because the mechanisms underlying this entity are the same ones that determine the more severe form. Findings provide evidence that iron overload is associated with increased liver damage and collagen deposition. Transforming growth factor-beta1 released by hepatic stellate cells during chronic liver injury plays a critical role in liver apoptosis and fibrogenesis. Objective To verify whether both the forms of non-alcoholic fatty liver disease were really dissimilar, evaluating the serum profile of two key parameters, indexes of severity. Methods A total of 123 patients (57 females) participated, forming three groups: forty five patients with fatty liver, 42 patients with non-alcoholic steatohepatitis and 36 with chronic hepatitis C. All had a biopsy-proven diagnosis. Measurements Serum concentrations of transforming growth factor-beta1 and ferritin. Results High concentrations of transforming growth factor-beta1 were noticed in patients suffering from both fatty liver and non-alcoholic steatohepatitis, 129.1 (45.4) versus 116.8 (42.2) ng/mL, P = 0.2; they were significantly superior to those of chronic hepatitis C patients 87.5 (39.5) ng/mL, P < 0.001. Ferritin levels were on average above normal values and similar in the three groups (P = 0.9), also when adjusted for gender (P = 0.5) and age (P = 0.3). Conclusion No difference between serum concentrations of transforming growth factor-beta1 and ferritin in fatty liver and non-alcoholic steatohepatitis suggests that these forms share more common aspects, regarding their progression, than previously thought.

Two sets of modules have been sent around to different testing installations across Europe, one set to laboratories performing indoor calibrations and one set to laboratories performing outdoor power and energy ratings. The results show that for crystalline and poly-crystalline devices, a very good agreement between laboratories has been achieved. A lower agreement between laboratories has been achieved for thin film devices and further need for research is identified

In the current market, the specific annual energy yield (kWh/kWp) of a PV system is gaining in importance due to its direct link to the financial returns for possible investors who typically demand an accuracy of 5% in this prediction. This paper focuses on the energy prediction of photovoltaic modules themselves, as there have been significant advances achieved with module technologies which affect the device physics in a way that might force the revisiting of device modelling. The paper reports the results of a round robin based evaluation of European modelling methodologies. The results indicate that the error in predicting energy yield for the same module at different locations was within 5% for most of the methodologies. However, this error increased significantly if the nominal nameplate rating is used in the characterization stage. For similar modules at the same location the uncertainties were much larger due to module-module variations.

In BIPV design with c-Si cells, ventilation is important in order to keep cells as cool as possible. To allow a good ventilation it is therefore generally preferred to mount the modules separated from the existing roof. In the case of sloped roofs the modules are superimposed to the existing roof and for flat roofs separated tilted mounting structures with wind loads are used instead, but both are no real building integrations. In this paper we analyse the behaviour and the energy yield of a 15.36 kWp PV system based on flexible triple-junction thin-film amorphous silicon modules laminated together with a single ply roofing system based on a flexible polyolefine (FPO) membrane which acts as a waterproofing system. Compared to c-Si modules, a thermal isolated BIPV design matches the best the thermal behaviour of a-Si technologies

A model for investigating the dynamic behaviour of solar cells, which allows the simulation of the measurements process with flash solar simulators, is presented in this paper. This model is then applied to the simulation of measurement processes currently employed by common solar simulator types. It is shown that the cell capacitance, the series resistance and cell area can all influence the measurements, giving rise to transient errors, especially in short flash solar simulators. It is also shown that point distribution as well as scan time also have significant importance.

The Romans built the ancient town of Grumentum during the 3rd century B.C. in the southern part of the Agri high Valley (Basilicata Region, Southern Italy) near the confluence of the Sciaura stream in the Agri River. Now it is one of the most important archaeological sites of Southern Italy. In fact, after a period of wars in this area between Romans and Carthaginians, a great deal of restoration was started in 57 B.C. These works affected the city walls, public buildings and finally endowed the Roman colony with important infrastructures, such as the new aqueduct. In this work, we attempt to reconstruct the ancient layout of the Roman aqueduct of Grumentum. As a starting point, we followed some descriptions from the 19th century, when the structure was still well preserved. Then, we performed a multidisciplinary geophysical approach to the best preserved remains of the aqueduct. In particular, the geophysical investigation started with the use of a portable GPS allowing us to acquire the co-ordinates of the outcropping rests of the ancient structure. Then, we used an optical pumping magnetometer to perform seven gradiometric maps over a broad area of about 8000 m2. From the literature descriptions, dating to the first part of the 19th century, we can deduce that the state of preservation of the Roman aqueduct was much better than the present one. Thus we can hypothesise as the cause of its fast involution the fact that it was located in the epicentral area of the large destructive earthquake which occurred in the Basilicata Region in 1857 (Mallet, 1862). To this aim, we performed a first attempt to correlate the state of preservation of the aqueduct remains with the local seismic amplification by means of the HVSR (Horizontal to Vertical Spectral Ratio) technique. This survey allowed us to obtain the site amplification spectra along the aqueduct layout and assess the fundamental vibration frequency of the investigated structure. The possibility of landslides was ruled out by a careful geological survey. The relationship between aqueduct path and damage should then be attributed to closeness to earthquake seismogenic fault.