1,721,092 research outputs found
Comparative analysis of crystalline and double junction amorphous silicon modules performance in outdoor conditions
No full texthe paper deals with an extensive photovoltaic (PV) modules monitoring activity carried out at the outdoor station ESTER (Solar Energy TEst and Research) of the University of Rome Tor Vergata, Italy. The purpose of the work was to evaluate and compare the performance of PV silicon modules of polycrystalline (poli-Si) and amorphous (a-Si) technologies during a medium-term outdoor exposure at optimized tilt angle, facing south. Two PV modules, one polycrystalline silicon and one double-junction amorphous silicon, have been exposed since May 2009 until Oct. 2010. A complete characterization of the weather conditions at the site during the test has been performed, and the most relevant parameters for the performance comparison of the two technologies have been derived. In order to compare different technologies and power productions, the energy yield (Y) and performance ratio (PR) for the two modules have been evaluated on a monthly and yearly basis. The typical seasonal trend of PR has been observed for the polycrystalline module, essentially due to the temperature influence on the module performance. For the a-Si module, instead, a degradation trend has been observed for the first months of operation. Subsequently, a significant recovery in the PR and energy production has been registered
Energy Efficiency in Buildings and Innovative Materials for Building Construction
Full text linkThe main topics of this Special Issue regard energy efficiency in buildings and the use of innovative materials for design and retrofitting to pursue this goal [...
Influence of Average Photon Energy index on solar irradiance characteristics and outdoor performance of photovoltaic modules
No full textSolar spectral irradiance measurements on a routinely basis are relevant to study the influence of solar spectrum on the photovoltaic (PV) module performance, especially for thin film and third generation PV. Two spectroradiometers from EKO were added to the instrumentation available at the ESTER outdoor station of the University of Rome Tor Vergata. A detailed characterisation of the spectral irradiance at the site was carried on during more than 6 months of monitoring activity measuring spectral solar irradiance in the range 350–1700 nm with a time interval of 10 min on a horizontal plane. A wide variety of spectra were acquired in various weather conditions, and indications about the spectra behaviour on a daily and seasonal basis were obtained. Moreover, information about the effect of the weather conditions on the solar radiation spectral distribution were identified. The Average Photon Energy index was used as an indicator of the spectra characteristics. The same index was also used to evidence the solar spectrum influence on polycrystalline and double junction amorphous silicon PV modules
Solar spectral irradiance measurements relevant to photovoltaic applications
Full text linkRecently, two spectroradiometers from EKO have been added to the instrumentation available
at the ESTER outdoor station of the University of Rome Tor Vergata, with the aim to
characterize the spectral irradiance at the site and evaluate its influence on the performances of
photovoltaic modules, especially thin films and third generation devices as Dye Sensitized
Solar Cells (DSSC). The paper will present the results of more than six months monitoring
activity where the spectral solar irradiance in the range 350 nm – 1,700 nm has been measured
continuously with a time interval of 10 minutes on a horizontal plane. A wide variety of spectra
have been acquired in various weather conditions and first indications about the spectra
behaviour on a daily and seasonal basis have been obtained. Moreover also some information
about the effect of the weather conditions on the solar radiation spectral distribution will be
presented
A method based on environmental monitoring and building dynamic simulation to assess indoor climate control strategies in the preventive conservation within historical buildings
No full textThis paper proposes a multidisciplinary method to provide improved conservation strategy and thermal comfort for visitors in historical buildings. The method combines microclimate observations along with the dynamic simulation of the building and an empirical evaluation of the degradation of hygrosocopic artifacts. It was applied to a historic building in Priverno (Italy) where cracks along the tangential direction in valuable wooden ceilings were observed. The method produced an identification strategy for temperature control that, if applied, would reduce the total size of cracks from 0.25 mm to 0.10 mm
Performance assessment of a heat and moisture dynamic simulation model in IDA ICE by the comparison with WUFI Plus
Full text linkRecently, in the field of preventive conservation, the use of accurate whole-building dynamic simulation models is becoming an effective approach for preventing degradation phenomena due to changes in indoor historic climate. Among microclimate parameters, the moisture plays a key role in the degradation of organic-hygroscopic artworks as well as in the durability of building components. Some simulation codes combine both heat and moisture transfer calculations, however their capability to accurately model the moisture transport is limited. The HMWall model coupled with IDA Indoor Climate and Energy (IDA ICE) software is one of those models. This study aims at comparing the performance of the HMWall model with respect to WUFI Plus, developed by Fraunhofer Institute for Building Physics (IBP). Temperature (T) and relative humidity (RH) provided by both codes in the case of a building envelope with no infiltration, windows and incoming solar radiation, are compared. This allows to assess whether both models calculate the moisture transport throughout walls in the same way. Dynamic simulations have been run over a year by using different T-RH outdoor conditions. Even if both models are based on the same heat and moisture transport equations, RH behaviour simulated by HMWall is significantly different from that by WUFI Plus. This mainly depends on the calculation of saturated vapour pressure (psat) inside the material. Then, the Common Exercise 3 has been applied to test if HMWall were capable to affect indoor RH when cladding materials with different sorption behaviour are used. The new HMWall implemented model is resulted more effective than the previous one, and in the case of simplified building, RHs modelled by both programs are highly correlated
Performance analysis of PV modules of various technologies after more than one year of outdoor exposure in Rome
Full text linkThe paper deals with an extensive PV modules monitoring activity carried out at the outdoor
station ESTER of the University of Rome Tor Vergata. The purpose of the work was to
evaluate and compare the performances of PV silicon modules of polycrystalline and
amorphous technologies during a medium term outdoor exposure at optimized tilt angle, facing
south. Two PV modules, one polycrystalline by Kyocera and one double junction amorphous
by EPV Solar have been exposed since May 2009. A complete characterization of the weather
conditions at the site during the test has been performed and the most relevant parameters for
the performance comparison of the two technologies have been derived. In order to compare
different technologies and power productions, the energy Yield (Y) and Performance Ratio
(PR) for the two modules have been evaluated on a monthly and yearly basis. The typical
seasonal trend of PR has been observed for the polycrystalline module, essentially due to the
temperature influence on the module performances. For the EPV module, instead, a
degradation trend has been observed for the first months of operation. Subsequently a
significant recovery in the PR and energy production has been registered
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