Review of the Performance of Residential PV systems in Belgium

The main objective of this paper is to review the state of the art of residential PV systems in Belgium by the analysis of the operational data of 993 installations. For that, three main questions are posed: how much energy do they produce? What level of performance is associated to their production? Which are the key parameters that most influence their quality? This work brings answers to these questions. A middling commercial PV system, optimally oriented, produces a mean annual energy of 892 kWh/kWp. As a whole, the orientation of PV generators causes energy productions to be some 6% inferior to optimally oriented PV systems. The mean performance ratio is 78% and the mean performance index is 85%. That is to say, the energy produced by a typical PV system in Belgium is 15% inferior to the energy produced by a very high quality PV system. Finally, on average, the real power of the PV modules falls 5% below its corresponding nominal power announced on the manufacturer's datasheet. Differences between real and nominal power of up to 16% have been detected

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

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

Effect of operating temperature on degradation of solder joints in crystalline silicon photovoltaic modules for improved reliability in hot climates

Accelerated degradation of solder joint interconnections in crystalline silicon photovoltaic (c-Si PV) modules drives the high failure rate of the system operating in elevated temperatures. The phenomenon challenges the thermo-mechanical reliability of the system for hot climatic operations. This study investigates the degradation of solder interconnections in c-Si PV modules for cell temperature rise from 25 °C STC in steps of 1 °C to 120 °C. The degradation is measured using accumulated creep strain energy density (Wacc). Generated Wacc magnitudes are utilised to predict the fatigue life of the module for ambient temperatures ranging from European to hot climates. The ANSYS mechanical package coupled with the IEC 61,215 standard accelerated thermal cycle (ATC) profile is employed in the simulation. The Garofalo creep model is used to model the degradation response of solder while other module component materials are simulated with appropriate material models. Solder degradation is found to increase with every 1 °C cell temperature rise from the STC. Three distinct degradation rates in Pa/°C are observed. Region 1, 25 to 42 °C, is characterised by degradation rate increasing quadratically from 1.53 to 10.03 Pa/°C. The degradation rate in region 2, 43 to 63 °C, is critical with highest constant magnitude of 12.06 Pa/°C. Region 3, 64 to 120 °C, demonstrates lowest degradation rate of logarithmic nature with magnitude 5.47 at the beginning of the region and 2.25 Pa/°C at the end of the region. The module fatigue life, L (in years) is found to decay according to the power function L=721.48T-1.343. The model predicts module life in London and hot climate to be 18.5 and 9 years, respectively. The findings inform on the degradation of c-Si PV module solder interconnections in different operating ambient temperatures and advise on its operational reliability for improved thermo-mechanical design for hot climatic operations

A review of photovoltaic module technologies for increased performance in tropical climate

The global adoption and use of photovoltaic modules (PVMs) as the main source of energy is the key to realising the UN Millennium Development Goals on Green Energy. The technology – projected to contribute about 20% of world energy supply by 2050, over 60% by 2100 and leading to 50% reduction in global CO2 emissions – is threatened by its poor performance in tropical climate. Such performance discourages its regional acceptance. The magnitude of crucial module performance influencing factors (cell temperature, wind speed and relative humidity) reach critical values of 90 °C, 0.2 m/s and 85%, respectively in tropical climates which negatively impact module performance indices which include power output (PO), power conversion efficiency (PCE) and energy payback time (EPBT). This investigation reviews PVM technologies which include cell, contact and interconnection technologies. It identifies critical technology route(s) with potential to increase operational reliability of PVMs in the tropics when adopted. The cell performance is measured by PO, PCE and EPBT while contacts and interconnections performance is measured by the degree of recombination, shading losses and also the rate of thermo-mechanical degradation. It is found that the mono-crystalline cell has the best PCE of 25% while the Cadmium Telluride (CdTe) cell has the lowest EPBT of 8-months. Results show that the poly-crystalline cell has the largest market share amounting to 54%. The CdTe cell exhibits 0% drop in PCE at high-temperatures and low irradiance operations – demonstrating least affected PO by the conditions. Further results establish that back contacts and back-to-back interconnection technologies produce the least recombination losses and demonstrate absence of shading in addition to possessing longest interconnection fatigue life. Based on these findings, the authors propose a PVM comprising CdTe cell, back contacts and back-to-back interconnection technologies as the technology with latent capacity to produce improved performance in tropical climates

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

Temperature and color management of silicon solar cells for building integrated photovoltaic

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