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With the rapid increase in solar photovoltaic (PV) installation capacity, the strain on grid transmission burden has intensified. A house energy management system is recognized as an effective solution to mitigate this grid burden. However, existing research has not fully explored the potential of battery utilization and the forecasting of uncertainties. In this paper, a novel multi-objective optimization framework based on the genetic algorithm-based method for the house energy management system is proposed, to enhance renewable self-consumption, improve on-site renewable self-sufficiency, and optimize economic benefits for users. The framework integrates an artificial neural network for predictions of meteorological data and user load at a 5-minute temporal resolution, enabling the simulation and optimization of the PV-battery-flexible load system. Emphasizing deferrable loads, constant-temperature control loads, and batteries, the proposed framework devises optimal strategies for distributed PV battery systems in residential. It harnesses load flexibility and battery storage capabilities while incorporating comfort assessment metrics. This approach significantly improves the system's economic and technical performance metrics, with system self-consumption rate, self-sufficiency rate, and cost reduction ratio improved by 13.5%, 11.3%, and 6.2%, respectively, compared to the basic strategy. Additionally, the optimization of the air conditioning system enhances alignment with the photovoltaic generation, resulting in a 9.8% reduction in energy consumption and a 9.4% decrease in electricity costs, while maintaining user comfort at an acceptable level. The proposed framework promotes the practical application of renewable management systems, highlighting renewable energy efficient utilization, grid dependency reduction, and user economic benefit increase. [ABSTRACT FROM AUTHOR]

The secondary solar heat gain, defined as the heat flows from glazing to indoor environment through longwave radiation and convection, grows with the increasing of glazing absorption. With the rapid development and application of spectrally selective glazing, the secondary solar heat gain becomes the main way of glazing heat transfer and biggest proportion, and indicates it should not be simplified calculated conventionally. Therefore, a dynamic secondary solar heat gain model is developed with electrochromic glazing system in this study, taking into account with three key aspects, namely, optical model, heat transfer model, and outdoor radiation spectrum. Compared with the traditional K-Sc model, this new model is verified by on-site experimental measurements with dynamic outdoor spectrum and temperature. The verification results show that the root mean square errors of the interior and exterior glass surface temperature are 3.25 °C and 3.33 °C, respectively, and the relative error is less than 10.37%. The root mean square error of the secondary heat gain is 13.15 W/m2, and the dynamic maximum relative error is only 13.2%. The simulated and measured results have a good agreement. In addition, the new model is further extended to reveal the variation characteristics of secondary solar heat gain under different application conditions (including orientations, locations, EC film thicknesses and weather conditions). In summary, based on the outdoor spectrum and window spectral characteristics, the new model can accurately calculate the increasing secondary solar heat gain in real time, caused by spectrally selective windows, and will provide a computational basis for the evaluation and development of spectrally selective glazing materials. [ABSTRACT FROM AUTHOR]

Self-powered photovoltaic windows, which integrate photovoltaic with electrochromic devices, have attracted widespread attention of scholars since they can generate electricity in situ and reduce building energy consumption by modulating the transmitted solar radiation. However, previous studies mainly focused on the material development and performance characterization, lack of comfort assessment and energy saving potential of its application to buildings. To address this issue, an adjustable semi-transparent photovoltaic (ATPV) window which integrates CdTe-based photovoltaic and WO3-based electrochromic, was taken as the research object, and a novel rule-based control strategy taking the beam solar radiation luminous efficacy (CtrlEff) as decision variable was proposed for the first time. The ATPV window model was established in WINDOW software based on the measured data, and then it was exported to integrated with a medium office building model in EnergyPlus for performance evaluation including the visual comfort, thermal comfort, net energy consumption, and net-zero energy ratio. The results of a case study in Changsha (E 112°, N 28°) indicated that the ATPV window under the CtrlEff strategy can effectively reduce the southward and westward intolerable glare by 86.9% and 94.9%, respectively, and increase the thermal comfort hours by 5% and 2%, compared to the Low-E window. Furthermore, the net-zero energy consumption can be decreased by 58.7%, 65.7%, 64.1%, and 53.8% for south, west, east, and north orientations, and the corresponding net-zero energy ratios are 65.1%, 54.6%, 62.7%, and 61.6%, respectively. The findings of this study provide new strategies for the control and optimization of the adjustable window. [ABSTRACT FROM AUTHOR]

A model-based optimal dispatch framework was proposed to optimize operation of residential flexible loads considering their real-life operating characteristics, energy-related occupant behavior, and the benefits of different stakeholders. A pilot test was conducted for a typical household. According to the monitored appliance-level data, operating characteristics of flexible loads were identified and the models of these flexible loads were developed using multiple linear regression and K-means clustering methods. Moreover, a data-mining approach was developed to extract the occupant energy usage behavior of various flexible loads from the monitored data. Occupant behavior of appliance usage, such as daily turn-on times, turn-on moment, duration of each operation, preference of temperature setting, and flexibility window, were determined by the developed data-mining approach. Based on the established flexible load models and the identified occupant energy usage behavior, a many-objective nonlinear optimal dispatch model was developed aiming at minimizing daily electricity costs, occupants' dissatisfaction, CO2 emissions, and the average ramping index of household power profiles. The model was solved with the assistance of the NSGA-III and TOPSIS methods. Results indicate that the proposed framework can effectively optimize the operation of household flexible loads. Compared with the benchmark, the daily electricity costs, CO2 emissions, and average ramping index of household power profiles of the optimal plan were reduced by 7.3%, 6.5%, and 14.4%, respectively, under the TOU tariff, while those were decreased by 9.5%, 8.8%, and 23.8%, respectively, under the dynamic price tariff. The outputs of this work can offer guidance for the day-ahead optimal scheduling of household flexible loads in practice. [ABSTRACT FROM AUTHOR]

Vanadium dioxide (VO2) based thermochromic smart window is considered as the most promising approach for economizing building energy consumption. However, the high phase transition temperature (τc), low luminous transmission (Tlum), and solar modulation (ΔTsol) impose an invertible challenge for commercialization. Currently, smart window research surprisingly assumes that the sunlight radiates in one direction which is obviously not valid as most regions receive solar radiation at various angles in different seasons. For the first time, solar elevation angle is considered and 3D printing technology is employed to fabricate tilted microstructures for modulating solar transmission dynamically. To maximize energy‐saving performance, the architecture of the structures (tilt, thickness, spacing, and width) and tungsten (W) doped VO2 can be custom‐designed according to the solar elevation angle variation at the midday between seasons and tackle the issue of compromised Tlum and ΔTsol with W‐doping. The energy consumption simulations in different cities prove the efficiency of such dynamic modulation. This first attempt to adaptively regulate the solar modulation by considering the solar elevation angle together with one of the best reported thermochromic properties (τc = 40 °C, Tlum(average) = 40.8%, ΔTsol = 23.3%) may open a new era of real‐world‐scenario smart window research. [ABSTRACT FROM AUTHOR]

Abstract: In order to reduce the building's energy demand, different glass innovative technologies are currently under intensive research and development. However, applicability of a particular technology requires its extensive environmental and energy characterization in building integration. In this work, overall performance (thermal, optical, and electrical) of semitransparent PV windows from different technologies has been assessed and compared with conventional windows. Characterization studies include both field measurements and numerical simulations and reveal the energy saving potential of PV windows on the overall energy demand of an office room and Mediterranean climate conditions. Finally, building integration is optimized by maximizing energy efficiency while keeping acceptable indoor visual comfort for different PV technology, ratio of the glazing surface replaced by PV windows (cover ratio), and orientation. [ABSTRACT FROM AUTHOR]

This study proposed an exhaust air heat recovery and solar energy combined thermal compensation system (ESTC) for ground-coupled heat pumps. Based on the prediction of the next day’s exhaust air temperature and solar irradiance, an optimized thermal compensation (OTC) method was developed in this study as well, in which the exhaust air heat recovery compensator and solar energy compensator in the ESTC system run at high efficiency throughout various times of day. Moreover, a modified solar term similar days group (STSDG) method was proposed to improve the accuracy of solar irradiance prediction in hazy weather. This modified STSDG method was based on air quality forecast and AQI (air quality index) correction factors. Through analyzing the operating parameters and the simulation results of a case study, the ESTC system proved to have good performance and high efficiency in eliminating the heat imbalance by using the OTC method. The thermal compensation quantity per unit energy consumption (TEC) of ESTC under the proposed method was 1.25 times as high as that under the traditional operation method. The modified STSDG method also exhibited high accuracy. For the accumulated solar irradiance of the four highest daily radiation hours, the monthly mean absolute percentage error (MAPE) between the predicted values and the measured values was 6.35%. [ABSTRACT FROM AUTHOR]

A comprehensive simulation model has been developed in this paper to simulate the overall energy performance of an amorphous silicon (a-Si) based photovoltaic double-skin facade (PV-DSF). The methodology and the model simulation procedure are presented in detail. To simulate the overall energy performance, the airflow network model, daylighting model, and the Sandia Array Performance Model in the EnergyPlus software were adopted to simultaneously simulate the thermal, daylighting, and dynamic power output performances of the PV-DSF. The interaction effects between thermal, daylighting, and the power output performances of the PV-DSF were reasonably well modeled by coupling the energy generation, heat-transfer, and optical models. Simulation results were compared with measured data from an outdoor test facility in Hong Kong in which the PV-DSF performance was measured. The model validation work showed that most of the simulated results agreed very well with the measured data except for a modest overestimation of heat gains in the afternoons. In particular, the root-mean-square error between the simulated monthly AC energy output and the measured quantity was only 2.47%. The validation results indicate that the simulation model developed in this study can accurately simulate the overall energy performance of the semi-transparent PV-DSF. This model can, therefore, be an effective tool for carrying out optimum design and sensitivity analyses for PV-DSFs in different climate zones. The methodology developed in this paper also provides a useful reference and starting point for the modeling of other kinds of semi-transparent thin-film PV windows or facades. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

To meet the performance test of the International Thermonuclear Experimental Reactor correction coil conductors, a 50-kA superconducting transformer has been manufactured, which allows rating of test samples under different operating conditions at the Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP). This transformer system is made up of two concentric layer-wound superconducting solenoids with the primary inside the secondary. The 50-kA secondary winding consists of 4-turn rectangular cable-in-conduit conductor type. This paper describes the design and manufacture techniques of the 50-kA transformer, including a secondary conductor. The secondary terminal design and manufacture are also discussed. Finally, the first test results of the 50-kA transformer are presented. [ABSTRACT FROM AUTHOR]

The objective of the study is to investigate and optimize the solar flux uniformity of a fixed linear-focus Fresnel lens solar concentrator using a triangle cavity receiver. The effects of receiver parameters including the vertical distance from the cavity opening plane to the Fresnel lens f, receiver internal surface absorptivity αab, end reflection plane reflectivity ρr, solar declination angle δ and solar angle ω on the uniformity factor (UF) of a triangle cavity receiver were carried out. The effects of receiver parameters are evaluated with a significance test of critical factors. The results showed that the increase in f and δ would result in an increase in the UF. The average UF with f = 600, 625, 650, 675 and 700 mm, respectively, are 0.5030, 0.5858, 0.6337, 0.6576 and 0.6784 for ω in range of 0–60°. Moreover, the UF increases as αab decreases when other receiver parameters are constant for the δ of 0–8°. The ρr has a limited effect on the UF until δ becomes relatively larger and ω becomes relatively smaller. Furthermore, ω effects are most significant on the UF, followed by δ, f and αab. Setting a suitable f is the most economical and effective way to improve the UF. [ABSTRACT FROM AUTHOR]