Roadmap for the next-generation of hybrid photovoltaic-thermal solar energy collectors

Mellor, A.; Alonso-Álvarez, D.; Guarracino, Ilaria; Ramos, Antonio Callejo; Lacasta, A. Riverola; Llin, Lourdes Ferre; Murrell, A.; Paul, Douglas J.; Chemisana, Daniel; Markides, Christos N.; Ekins-Daukes, N. J.

doi:10.1016/j.solener.2018.09.004

Cited by 88 publications

(30 citation statements)

References 32 publications

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“…In the built environment, non-concentrating PV panels are the most mature and widely-available technology for the distributed generation of electricity, while non-concentrating ST collectors are the most suitable for the provision of thermal energy for a diverse range of applications including domestic hot water and space heating in homes. More recently, "hybrid" PV-thermal (PVT) collectors have also been proposed for distributed applications [7], which combine PV modules with a heat-recovery configuration in order to provide simultaneous electrical and thermal outputs from the same array area, thus satisfying both the electrical and thermal needs of buildings and end-users [8]. Of particular interest are the integration of this technology in relevant buildings and the matching of the delivered energy outputs with the end-use demands, especially since the thermal, electrical and economic performance of PVT systems has been found to be highly dependent on various design and operational considerations such as materials and geometry [9], mode of circulation [10], relative sizes of the PV and thermal absorber areas [11], and required temperature and application of the thermal output [12].…”

Section: Introductionmentioning

confidence: 99%

Systematic testing of hybrid PV-thermal (PVT) solar collectors in steady-state and dynamic outdoor conditions

et al. 2019

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Hybrid photovoltaic-thermal (PVT) collectors have been proposed for the combined generation of electricity and heat from the same area. In order to predict accurately the electrical and thermal energy generation from hybrid PVT systems, it is necessary that both the steady-state and dynamic performance of the collectors is considered. This work focuses on the performance characterisation of non-concentrating PVT collectors under outdoor conditions. A novel aspect of this work is the application of existing methods, adapted from relevant international standards for flat plate and evacuated tube solar-thermal collectors, to PVT collectors for which there is no formally established testing methodology at present. Three different types of PVT collector are tested, with a focus on the design parameters that affect their thermal and electrical performance during operation. Among other results, we show that a PVT collector suffers a 10% decrease in thermal efficiency when the electricity conversion is close to the maximum power point compared to open-circuit mode, and that a poor thermal contact between the PV laminate and the copper absorber can lead to a significant deterioration in thermal performance. The addition of a glass cover improves the thermal efficiency, but causes electrical performance losses that vary with the glass transmittance and the solar incidence angle. It is found that the reduction in electrical efficiency at large incidence angles is more significant than that due to elevated temperatures representative of water-heating applications. Dynamic performance is characterised by imposing a step change in irradiance in order to quantify the collector time constant and effective heat capacity. This paper demonstrates that PVT collectors are characterised by a slow thermal response in comparison to ordinary flat plate solar-thermal collectors, due to the additional thermal mass of the PV layer. A time constant of ∼ 8 min is measured for a commercial PVT module, compared to < 2 min for a flat plate solar-thermal collector. It is also concluded that the use of a lumped, first-order dynamic model to represent the thermal mass of the PVT collector is not appropriate under certain irradiation regimes and may lead to inaccurate predictions of the system performance. This paper outlines a procedure for the testing and characterisation of solar collectors, provides valuable steady-state and dynamic performance characterisation data for various PVT collector designs, and also provides a framework for the application of this data in a system model to provide annual performance predictions in a range of geographical settings.

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Section: Introductionmentioning

confidence: 99%

Systematic testing of hybrid PV-thermal (PVT) solar collectors in steady-state and dynamic outdoor conditions

et al. 2019

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“…The economic performance of the PVT S-CHP system is at the medium level compared to the other more mature systems (PV panels, ETCs or their combinations). Considering that the technology and market readiness levels of PVT collectors are much lower than those of PV panels and ETCs, a large potential for further improvements are foreseen in the near future [39].…”

Section: Economic Performancementioning

confidence: 99%

“…To improve the thermal performance of PVT collectors, some researchers proposed to use flat-box structure [35] or microchannels [36] as alternative absorber-exchanger designs to the conventional sheet-and-tube type, while others considered using nanofluids [37] or heat pipe [38] for heat transfer enhancement. More recently, studies have shown that employing advanced emissivity control techniques [39] and spectral splitting concepts [40] into PVT collector designs emerge as promising directions for performance breakthrough.…”

Section: Introductionmentioning

confidence: 99%

Technoeconomic assessments of hybrid photovoltaic-thermal vs. conventional solar-energy systems: Case studies in heat and power provision to sports centres

et al. 2019

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This paper presents a comprehensive analysis of the energy, economic and environmental potentials of hybrid photovoltaicthermal (PVT) and conventional solar energy systems for combined heat and power provision. A solar combined heat and power (S-CHP) system based on PVT collectors, a solar-power system based on PV panels, a solar-thermal system based on evacuated tube collectors (ETCs), and a S-CHP system based on a combination of side-by-side PV panels and ETCs (PV-ETC) are assessed and compared. A natural gas fired internal combustion engine (ICE) CHP system is also analysed as a competing fossil-fuel based solution. Annual simulations are conducted for the provision of electricity, along with space heating, swimming pool heating and hot water to the University Sports Centre of Bari, Italy. The results show that, based on a total installation area of 4000 m 2 in all cases, the PVT S-CHP system outperforms the other systems in terms of total energy output, with annual electrical and thermal energy yields reaching 82.3 % and 51.3 % of the centre's demands respectively. As a booming solar technology, the PV system is the most profitable solar solution with the shortest payback time (9.4 years) and lowest levelised cost of energy (0.089 €/kWh). Conversely, the ETC solar-thermal system is economically inviable for the sports centre application and increasing the ETC area share in the combined PV-ETC S-CHP system is unfavourable due to the low natural gas price. Although the PVT S-CHP system has the highest investment cost, the high annual revenue from the avoided energy bills elevates its economic performance to between those of the conventional PV and ETC-based energy systems, with a payback time of 13.7 years and a levelised cost of energy of 0.109 €/kWh. At 445 tCO 2 /year, the CO 2 emission reduction potential of the PVT S-CHP system is considerably higher than those of the all other solar systems (254-317 tCO 2 /year). Compared to the solar energy systems, the ICE CHP system has the shortest payback time (6.2 years), but its CO 2 emission reduction (25 tCO 2 /year) is significantly lower. A high carbon price is beneficial for improving the cost-competitiveness of the solar energy systems, in particular the PVT S-CHP system, which would further boost its market penetration, helping to meet the carbon emission targets.

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“…The rate of global primary-energy consumption has been increasing rapidly with economic development and population growth, leading to increasing concerns relating to energy security, sustainability and environmental deterioration [1]. Renewable-energy technologies, and in particular distributed solar-cogeneration systems in the built environment, based on either conventional [2,3] (including with integrated thermal-energy storage [4,5]), but also more innovative/hybrid technologies [6][7][8], and improved efficiency energy-utilization solutions in commercial and industrial settings [9,10], have attracted interest as part of pathways aimed at fuel-use reduction and environmental impact alleviation [11]. In the context of thermal power-generation, a number of relatively mature technologies are being proposed for deployment in a wide range of applications, including systems based on a variety of power cycles.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and economic investigations of transcritical CO2-cycle systems with integrated radial-inflow turbine performance predictions

Song

Ren

et al. 2020

Applied Thermal Engineering

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Transcritical CO2 (TCO2) cycle systems have emerged as a promising power-generation technology in certain applications. In conventional TCO2-cycle system analyses reported in the literature, the turbine efficiency, which strongly determines the overall system performance, is generally assumed to be constant. This may lead to suboptimal designs and optimization results. In order to improve the accuracy and reliability of such system analyses and offer insight into how knowledge of these systems from earlier analyses can be interpreted, this paper presents a comprehensive model that couples TCO2-cycle calculations with preliminary turbine design based on the mean-line method. Turbine design parameters are optimized simultaneously to achieve the highest turbine efficiency, which replaces the constant turbine efficiency used in cycle calculations. A case study of heat recovery from an internal combustion engine (ICE) using a TCO2-cycle system with a radial-inflow turbine is then considered, with results revealing that the turbine efficiency is influenced by the system's operating conditions, which in turn has a significant effect on system performance in both thermodynamic and economic terms. A more generalized heat source is then considered to explore more broadly the role of the turbine in determining TCO2-cycle power-system performance. The more detailed turbine-design modelling approach allows errors of the order of up to 10-20% in various predictions to be avoided for steady-state calculations, and potentially of an even greater magnitude at off-design operation. The model allows quick preliminary designs of radial-inflow turbines and reasonable turbine performance predictions under various operating conditions, and can be a useful tool for more accurate and reliable thermo-economic studies of TCO2-cycle systems.

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Roadmap for the next-generation of hybrid photovoltaic-thermal solar energy collectors

Cited by 88 publications

References 32 publications

Systematic testing of hybrid PV-thermal (PVT) solar collectors in steady-state and dynamic outdoor conditions

Systematic testing of hybrid PV-thermal (PVT) solar collectors in steady-state and dynamic outdoor conditions

Technoeconomic assessments of hybrid photovoltaic-thermal vs. conventional solar-energy systems: Case studies in heat and power provision to sports centres

Thermodynamic and economic investigations of transcritical CO2-cycle systems with integrated radial-inflow turbine performance predictions

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