PV module temperature prediction at any environmental conditions and mounting configurations

Photovoltaic (PV) module temperature is known to significantly affect its power output and efficiency, while it has been shown to depend mainly on the ambient temperature, the solar irradiance incident on the PV plane and the wind speed, while to a lesser extent on the wind incidence angle and various other environmental parameters as well as PV module structural characteristics, module type, etc. The mounting configuration has been shown to play a significant role in the PV temperature developed and the power output. This paper presents an algorithmic approach for the prediction of PV module temperature at any environmental conditions based on the energy balance equation taking into account PV orientation, windward and leeward side, heat convection by natural and air forced flow, heat conduction and the radiated heat by the PV module. The results are compared to measured data under various outdoor conditions of ambient temperature, solar irradiance and wind speed. In addition, the predicted PV temperature is compared to predicted values from existing models. The robustness of the simulation algorithm developed in the prediction of PV module temperature is presented and its clear advantage over empirical models, which are fine tuned for the exact experimental conditions and/or experimental set ups under which they were developed, is illustrated. Furthermore, the coefficient f which relates the PV module temperature with the solar irradiance on the PV plane and the ambient temperature is examined for various configurations of free-standing fixed and sun-tracking PV system as well as building integrated photovoltaic (BIPV), illustrating essential differences in this and in the temperature developed in the PV module

A method of strategic evaluation of energy performance of Building Integrated Photovoltaic in the urban context

This paper presents an integrated bottom-up approach aimed at helping those dealing with strategical analysis of installation of Building Integrated Photo Voltaic (BIPV) to estimate the electricity production potential along with the energy needs of urban buildings at the district scale. On the demand side, hourly energy profiles are generated using dynamic building simulation taking into account actual urban morphologies. On the supply side, electricity generated from the system is predicted considering both the direct and indirect components of solar radiation as well as local climate variables. Python-based Algorithm editor Grasshopper is used to interlink four types of modelling and simulation tools as 1) generation of 3-D model, 2) solar radiation analysis, 3) formatting weather files (TMY data set) and 4) dynamic energy demand. The method has been demonstrated for a cluster of 20 buildings located in the Yasar University in Izmir (Turkey), for which it is found the BIPV system could achieve an annual renewable share of 23%, in line with the Renewable Energy Directive target of 20%. Quantitatively-compared demand and supply information at hourly time step shows that only some energy needs can be met by BIPV, so there is a need for an appropriate matching strategy to better exploit the renewable energy potential

Resonant Thermoelectric Nanophotonics

Photodetectors are typically based either on photocurrent generation from electron–hole pairs in semiconductor structures or on bolometry for wavelengths that are below bandgap absorption. In both cases, resonant plasmonic and nanophotonic structures have been successfully used to enhance performance. Here, we show subwavelength thermoelectric nanostructures designed for resonant spectrally selective absorption, which creates large localized temperature gradients even with unfocused, spatially uniform illumination to generate a thermoelectric voltage. We show that such structures are tunable and are capable of wavelength-specific detection, with an input power responsivity of up to 38 V W^(–1), referenced to incident illumination, and bandwidth of nearly 3 kHz. This is obtained by combining resonant absorption and thermoelectric junctions within a single suspended membrane nanostructure, yielding a bandgap-independent photodetection mechanism. We report results for both bismuth telluride/antimony telluride and chromel/alumel structures as examples of a potentially broader class of resonant nanophotonic thermoelectric materials for optoelectronic applications such as non-bandgap-limited hyperspectral and broadband photodetectors

Temperature Effects on Photovoltaic Energy Output Under Real Conditions: Weibull Model

International audiencePhotovoltaic (PV) modules are given a power rating at standard test conditions (STC) of 1000 W/m2 , AM1.5, and a module temperature of 25∘C. However, these conditions do not represent what is typically experienced under outdoor operation. PV technologies have different seasonal output behavior under real operating conditions due to variations of irradiance and different temperature coefficients of voltage and current that do influence on energy output. Solar photovoltaic resources can be modeled probabilistically, and a probability density function of the solar generation can be estimated. In this paper, we applied the Weibull analysis for energy output estimation to a small-scale photovoltaic power generator in real conditions and undergoing environmental stresses for a specific location. We studied two types of modules: crystalline silicon (c–Si) and amorphous silicon (a–Si) in real outdoor conditions. We measured and calculated monthly and annual power output and compared each system performance