This paper presents monitoring data and performance results of 12 photovoltaic systems installed in South Tyrol, which are based on different technologies, mainly crystalline and CdTe modules, and various dimension, from few kWp to more than 800 kWp. The target of the monitoring is an evaluation of performance ratio of the different systems, under the real regional climatic condition, for the benefit of installers and final users, and the collection of data to allow a better understanding of loss mechanisms. This paper summarizes 18 months of monitoring results. The monitored data include current from the PV array, array voltage, AC power delivered, global horizontal irradiance and ambient temperature, obtained from 26 weather station scattered on the region, and array temperature. The purpose of this work is to compare and to present operational performance results of grid-connected PV systems, as collected and elaborated for the project CoPES; a cooperation project between applied research institutions and several SMEs. The obtained results were used mainly as a feedback for the industry concerned with installation; besides that, selected results were used as a reference parameter for the validation of a new code for the efficiency prediction modeling of a PV module operating in outdoor conditions.

Universita di Ferrara, Dipartimento di Fisica, Via Saragat 1, 44100 Ferrara, Italy. *Phone: +39 0471 055337; Fax: +39 0471 055339; E-mail: maurizio.armani@eurac.edu ABSTRACT: This paper presents monitoring data and performance results of 12 photovoltaic systems installed in South Tyrol, which are based on different technologies, mainly crystalline and CdTe modules, and various dimension, from few kWp to more than 800 kWp. The target of the monitoring is an evaluation of performance ratio of the different systems, under the real regional climatic condition, for the benefit of installers and final users, and the collection of data to allow a better understanding of loss mechanisms. This paper summarizes 18 months of monitoring results. The monitored data include current from the PV array, array voltage, AC power delivered, global horizontal irradiance and ambient temperature, obtained from 26 weather station scattered on the region, and array temperature. The purpose of this work is to compare and to present operational performance results of grid-connected PV systems, as collected and elaborated for the project CoPES; a cooperation project between applied research institutions and several SMEs. The obtained results were used mainly as a feedback for the industry concerned with installation; besides that, selected results were used as a reference parameter for the validation of a new code for the efficiency prediction modeling of a PV module operating in outdoor conditions. Keywords: system performance, monitoring, simulation 1 INTRODUCTION The aim of the activities conducted under the project CoPES [1] was to be the basis for the development, in South Tyrol, of a pole/centre for the know-how transfer in photovoltaics, allowing local companies to acquire strong positions as actors in PV market in Italy. Research activities were carried out using tools such simulation and monitoring of certain facilities installed during the development of the project. Monitoring activities and simulation carried out had not only the aim to deepen knowledge about the processes of generation from photovoltaic source, but also to transfer information to designers and installers with repercussions on the market, improving the quality of design, margins of economic return, compared with a greater accuracy in forecasting yield and, more generally, increasing the appeal shown by the sector. This need occurs as a result of issues relating to estimates of return linked to the difference between the operating conditions set as standard conditions (STC) and those relating to the losses attributable to real outdoor operating conditions. In this paper the simulation results from different selected software packages are compared with the results obtained from the monitoring campaign, which at its end counts 1935.37 kWp monitored, equivalent to 24.11% of total power installed in the Province at the time of conclusion of this project, the means by which the data were collected. 2 MONITORING The selected plants shown in Table I are characterized by different technologies, distributed in the southtyrolean territory, equipped with automatic, commercial, data acquisition systems supplied by the producers of the inverters. The monitored plants exploit a service of remote monitoring based on measurements taken by the same inverter (embedded monitoring), summarized in some cases from measurements taken directly from sensors on considered sites, such as temperature of the modules and radiation in the plane of the modules, or using information derived from the provincial weather stations scattered around South Tyrol.

We present magnetization and muon spin resonance (μSR) data on the single layered manganite LaSrMnO4, nominally containing no holes. Magnetization data corroborate antiferromagnetic (AF) spin order but it also suggest additional static moments with a magnetic anisotropy parallel to the AF easy axis, at low temperatures. Our μSR data confirm the existence of these statics moments and imply that they are in a metastable, frozen state. Upon heating, the metastability disappears and for the additional moments a very slow dynamic is detected.

We report on the comparison of time variations observed in the gamma ray component of cosmic radiation as measured by our detectors for Environmental Radiation operated in different locations at different time of the solar activity cy- cle. We study the response of these detectors in the occasion of Forbush decreases and ground level events, and compare our observation with those reported by the neutron monitor network.

Since 1995 we have carried out measurements of the gamma ray flux in the 3-15 MeV energy range at six different atmospheric depths, from ground level to aircraft altitude, and at different geomagnetic cut-off. We estimate the attenuation length of the gamma-ray component in the atmosphere and make a comparison with previous results. 1. Introduction The interaction of cosmic rays with atmospheric nuclei and terrestrial matter originates different radiation components that, together with the products of natural and/or artificial radioactivity sources constitute a variable radiation background, that has been named Environmental Radiation (ER)[5]. The very low energy component of secondary cosmic rays (CR) was called mollissima, or ultrasoft, by [1]. The monitoring of the ER intensity and of its time variation is

Since 1995 we have carried out measurements of the gamma ray flux in the 3-15 MeV energy range at six different atmospheric depths, from ground level to aircraft altitude, and at different geomagnetic cut-off. We estimate the attenuation length of the gamma-ray component in the atmosphere and make a comparison with previous results. 1. Introduction The interaction of cosmic rays with atmospheric nuclei and terrestrial mat- ter originates different radiation components that, together with the products of natural and/or artificial radioactivity sources constitute a variable radiation back- ground, that has been named Environmental Radiation (ER)(5). The very low energy component of secondary cosmic rays (CR) was called mollissima, or ultra- soft, by (1). The monitoring of the ER intensity and of its time variation is interesting not only per se, but also for its influence on human life and activity. Since 1995 we have started a world-wide survey of the ER in order to study, in a systematic way, the time and spatial variations of its both components: in Italy (at sea level in Bologna, at the Laboratorio Mt. Cimone and at Gran Sasso National Laboratories), at Terra Nova Bay in three different italian expeditions to Antarctica and even during the sea voyages from Italy to Antarctica and back, at the Svalbard Islands in the Arctic region, in Nepal at 5050 m a.s.l. and in Tun- guska (Central Siberia). During the latter expedition one detector was operated on board an aircraft that attained the maximum altitude of 8400 m. Here we present the study of the altitude dependence of the energy spectra of the γ− rays with E > 3 MeV originated by CR, after taking into account that the measurements were made at different locations and at different times of a solar activity cycle (see Table 1). Corrections for different detector design (mainly the shield) were also applied. From the spectra observed at several heights we are able to deduce the atmospheric attenuation length of this component. Finally we could investigate the presence of γ-lines in the spectra taken at aircraft altitudes.

We report on the comparison of time variations observed in the gamma ray component of cosmic radiation as measured by our detectors for Environmental Radiation operated in different locations at different time of the solar activity cycle. We study the response of these detectors in the occasion of Forbush decreases and ground level events, and compare our observation with those reported by the neutron monitor network.

With the overall critical current density,J c , remaining low for PbMo6S8, the addition of 0.3 at. % Sn noticcably improved the performance. The enhancement occurs despite the presence of excess Pb and a slightly suppressedT c . The increase inJ c can be attributed to a better homogeneity with respect to the chemical composition of the samples, which may be as a consequence of Sn substitution in the lattice. Detailed calorimetric investigation of undoped PbMo6S8 showed aT c distribution down to 9 K evidenced by a smearing ofT c . This may be due to a progressive degradation of the sample quality leading to a plausible off-stoichiometry. High-resolution Auger electron spectroscopic experiments suggest a variation in composition indicating excellent correspondence with the specific heat data. However, no such deviation was detected for the Sn-doped samples and therefore the observed raise inJ c . The results are discussed in conjunction with oxygen, lead and tin incorporated PbMo6S8.

Critical current density (Jc) has been measured in hot isostatically and uniaxially pressed bulk samples of PbMo6S8 (PMS) and SnMo6S8 (SMS) Chevrel phase superconductors (CPS). The obtained pinning force densities (Fp(B, T)) show a scsling in a wide range of temperature (T = 4.2 K−Tc) and field (B = 0–9 T), which is in good agreement with the predictions of the flux line shear (FLS) model. However, the magnitude of Fp is an order of magnitude smaller than the expected values. The PMS sample hot pressed at relatively high temperatures (1200°C) shows long tails in the scaled Fp(B, T) data. In contrast, the SMS samples sintered at similar temperatures show double peaks in Fp(B) for temperatures below 10.5 K. For both compounds the pseudo upper critical field (B∗c2(T)) extracted from the Jc data, especially near Tc, shows deviation from the expected ideal Bc2(T) dependence. The results point out a correlation of Jc and B∗c2s with the morphology of the grain boundaries in terms of granularity and degradation of the superconducting properties.

Synchrotron and Guinier x-ray powder diffraction data as a function of temperature on a superconducting PbMo6S8 sample (Tc=14.7 K) showed evidence for a subtle structural phase transition at Tl=140 K, leading from a rhombohedral high-temperature to a triclinic low-temperature modification. The transition is incomplete and presents a hysteresis of about 110 K. The triclinic cell parameters obtained at 130 K, a=6.534(9) Å, b=6.532(9) Å, c=6.529(9) Å, α=89.27(8)°, β=89.12(8)°, γ=88.97(8)°, show that the distortion affects mainly the angles (δα/αr=0.3%) and less the edges (δa/ar<0.1%). This result contrasts with previous neutron diffraction work [Phys. Rev. 35, 5365 (1987)] where the distortion was found to be much greater and to affect both the angles and the edges (δa/ar=1.2%, δα/αr=1.2%), and to be of the same order of magnitude than in the MMo6S8 (M=Sr,Ba,Eu) analogues (M=Ba: δa/ar=1.2%,δα/αr=3.5%). Guinier data on an oxygen containing sample having a lower superconducting transition temperature (Tc=10.5 K) showed a smaller distortion that started at lower temperature (Tl=100 K).

The influence of Sn on the enhancement of critical current densities, J/sub c/, in bulk samples of PbMo/sub 6/S/sub 8/ has been systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), AC susceptibility, and specific heat experiments. The results indicate that the addition of Sn, as an adjunction (dopant) or as a substitution, has a considerable effect on the structural, superconducting, microstructural and grain boundary properties. The observed increase in J/sub c/ is discussed in terms of improved interconnectivity between the grains, better homogeneity of the samples, and, more importantly, lower grain boundary contamination.<>

A full account of positive-muon spin-rotation (mu+SR) studies on the systematics of the magnetic penetration depth lambda in the isotropic Chevrel-phase superconductors SnMo6S8-xSex (x=0,1,4,7) and PbMo6S8-xSex (x=0,4) is presented. The absolute determination of lambda from the muSR data necessitates a careful analysis of the muSR line shape and a comparison with simulated data, taking into account distortions of the flux-line lattice and a distribution of demagnetization factors in the sintered granular polycrystalline probes investigated. A correlation between T(c) and 1/lambda2 iS found which supports a recently developed quantum percolation model.