Energy Payback Time Research Articles

A Comprehensive Life Cycle Assessment Study of Innovative Bifacial Photovoltaic Applied on Building

Bifacial photovoltaic (BPV) module is a new type of photovoltaic module, which can simultaneously utilize solar radiation from the front and the back side to produce more power generation. In this article, this BPV module was innovatively applied on building, and a demonstration building was designed and set up. The building includes the diversification of forms and reflection utilization. The BPV module improved power generation performance by 10.7% ~ 12.7% compared with the mono-facial module. Combined with experimental test, simulation and enterprise investigation, a multi-index life cycle assessment (LCA) method for BPV modules is established, and include economic, energy and environmental indicators. The application potential of different forms of BPV modules is analyzed and compared with mono-facial module. The energy payback time (EPBT) and greenhouse gas payback time (GPBT) of BPV solar house were 6.6 and 2.3 years, while the EPBT and GPBT of BPV inclined roof were 5.0 and 1.7 years. Economic analysis shows that BPV applied on building can compensate for all the input cost and even have more additional benefits. Compared with mono-facial module, BPV modules have higher benefits in all aspects. According to the LCA results, the optimization suggestions for the BPV demonstration building are given.

Classical Physics-based Renewable and Sustainable Energy Transition Concept

By many accounts, Lorentz was ahead of his time by suggesting before quantum mechanics that some disturbances, like waves, travel with particles through a vacuum without moving it. The waves associated with the Lorentz metrics are described by the Klein-Gordon equation and dispersion relation w²=c²k²+w_c². In hydromechanics, they are known as non-propagating waves and w_c is a constant called the cutoff frequency. The waves are not propagating if their frequency is below the cutoff frequency w_c. Their group and phase velocity are related by vu=c², in the infinite k limit v=u=c. A quantum object is considered as a particle moving in resonance with wave characterized by the Klein-Gordon dispersion relation with cutoff or Compton frequencyw_c=mc²/ħ. This approach brings field values (group velocity and intensity of transverse non-propagating waves) into Maxwell's equations, and antiparticles or non-propagating waves with negative group velocity into Newtonian mechanics. In classical astrophysics, matter-antimatter interactions led to the universe expansion, formation of galaxiesand sources of intense cosmic radiation. Classical field theory could play a major role in clean energy research. In particular, concentrating solar power (CSP) systems, i.e. Stirling engine (SE) or small direct-heated tower, with thermal energy storage (TES), diffuse light-utilizing photovoltaic (PV) cell and 3D-printed thermal field emission (TFE) converters will dramatically lower the cost and energy payback time of the CSP technologies. The design explores recent developments in field-effect PV cells. 3D-printed TFE panels-integrated in TES or micro-channel solar receivers. The improved performance of the TFE converter compared to photovoltaic cells at high temperatures is attributed to the simultaneous use of diffusion and ballistic electron transport to harvest both thermal and photon energy. In addition, a gas cooled water moderated reactor is explored to integrate electrical-in-nature nuclear energy into smart micro-grids. and convert the most hazardous wastes into an emission-free fuel and medical isotopes. Transmutation reactor, in which depleted uranium acts initially as an absorber and later as fuel, behaves like fast reactors, but without their difficult control problems and high fissile fuel load.

Life Cycle Assessment of a Point-Absorber Wave Energy Array

Wave energy has a large global resource and thus a great potential to contribute to low-carbon energy systems. This study quantifies the environmental impacts of a 10MW array of 28 point-absorber wave energy converters, by means of a process-based life cycle assessment (LCA). Midpoint and Cumulative Energy Demand LCA results are presented over 19 impact categories, representing impacts encompassing human health, ecosystems and resource availability. Three scenarios are undertaken to represent the use phase of the array, identified as a particularly uncertain input, with very little long-term operation of wave energy arrays available to validate assumptions. The resultant global warming potential of the array ranges from 25.1- 46.0 gCO2e/kWh over a 95% confidence interval, 23-43 times lower than conventional fossil fuel electricity generation. The Energy Payback Time of the array ranges between 2.6-5.2 years. LCA results are found to be particularly sensitive to annual energy production across all impact categories, and to assumptions associated with the frequency of marine operations over a number of categories quantifying the production of greenhouse gases. This LCA has been undertaken at an early stage in the WEC product development and will inform innovative research focused on further reducing the environmental impacts of electricity generation.

Comparative observation of energy matrix and environ-economy for solar still systems

In the current scenario, where the water sources are contaminating very fast due to the speedy growth of population and a corresponding increase in the industries and other sectors necessary for the usual growth and survival of mankind. Hence, the water consumption goes up tremendously and the adverse effect that gives the contaminated water all around us as a byproduct. So, it must have self-sustainable and long-lasting water treatment technology that has higher energy payback time, better lifecycle energy conversion efficiency with a cheaper establishment that has the least adverse effects on the environment. In the same perspective, the current effort is based on the comparative observations of the single sloped and double sloped solar stills having different combinations of arrangements in that to take the comparable performances accordingly. And, it is recommended that out of the four different associations (fins with circular and square structures, cotton wick, and jute wick), solar still system having square fin structure shows the best results also having the least embodied energy i.e. 379.62 kWh in comparison to the other combining arrangement solar still systems in this current work. This system produces yield by 4.55 l for the 1 m2 effective still basin area per day and equivalent saving of 36600 kg CO2 for its entire life of working i.e. 30 yrs of serving life of the system. Furthermore, the corresponding earning of monetary value based on the carbon credit earned have been analyzed as $365.63 with relative payback with 0.48 yrs, and sequential conversion efficiency of the still system reported as 0.44 out of the proposed systems in this work.

An Evaluation of the Environmental Payback Times and Economic Convenience in an Energy Requalification of a School

The majority of Italian schools (70%) were built in the absence of any legislation related to energy efficiency, and therefore have very low energy performance due to aging or poor quality of construction. An energy retrofit of this building stock is needed to meet the current European goals on greenhouse gas emission reduction. The retrofit is also needed in order to guarantee adequate comfort levels in indoor spaces and good conditions for learning and educational activities, that are often not reached in poor quality constructions. This work presents the results of an interdisciplinary study related to the energy requalification of a school located in Ostia, near Rome in Italy, built in the 1960s with a steel structure and Eternit infill. The scope of the analysis is to verify the economic and environmental effectiveness of four proposed retrofit interventions concerning the replacement of fixtures and the installation of an insulating coat. The current thermal transmittance of the walls was evaluated through thermofluximetric measurements conducted in situ; dynamic simulations were performed to determine the current energy performance and the energy performances following the four proposed retrofit scenarios. Energy and carbon payback times were evaluated (by means of the life cycle analysis (LCA) approach) and the economic value was determined for each of the four proposed retrofits, using a probabilistic approach. The results show that the replacement of windows is the most convenient intervention from all points of view. The study provides evidence that an assessment of schools’ energy retrofits should include both economic and life cycle aspects.

Energetic-Environmental-Economic Feasibility and Impact Assessment of Grid-Connected Photovoltaic System in Wastewater Treatment Plant: Case Study

Wastewater treatment plants and power generation constitute inseparable parts of present society. So the growth of wastewater treatment plants is accompanied by an increase in the energy consumption, and a sustainable development implies the use of renewable energy sources on a large scale in the power generation. A case study of the synergy between wastewater treatment plants and photovoltaic systems, aiming to improve the energetic, environmental and economic impacts, is presented. Based on data acquisition, the energy consumption analysis of wastewater treatment plant reveals that the highest demand is during April, and the lowest is during November. The placement of photovoltaic modules is designed to maximize the use of free space on the technological area of wastewater treatment plant in order to obtain a power output as high as possible. The peak consumption of wastewater treatment plant occurs in April, however the peak production of the photovoltaic is in July, so electrochemical batteries can partly compensate for this mismatch. The impact of the photovoltaic system connectivity on power grid is assessed by means of the matching-index method and the storage battery significantly improves this parameter. Carbon credit and energy payback time are used to assess the environmental impact. The results prove that the photovoltaic system mitigates 12,118 tons of carbon and, respectively, the embedded energy is compensated by production in 8 ½ years. The economic impact of the photovoltaic system is analyzed by the levelized cost of energy, and the results show that the price of energy from the photovoltaic source is below the current market price of energy.

Fused-Ring Electron Acceptors for Photovoltaics and Beyond.

ConspectusEmerging solar cells that convert clean and renewable solar energy to electricity, such as organic solar cells (OSCs) and perovskite solar cells (PSCs), have attracted increasing attention owing to some merits such as facile fabrication, low cost, flexibility, and short energy payback time. The power conversion efficiencies (PCEs) of OSCs and PSCs have exceeded 18% and 25%, respectively.Fullerene derivatives have high electron affinity and mobility with an isotropic transport feature. Fullerene-based OSCs yielded superior PCEs to other acceptors and have dominated electron acceptor materials from 1995 to 2015. However, some drawbacks of fullerenes, such as weak visible absorption, limited tunability of electronic properties, laborious purification, and morphological instability, restrict further development of OSCs toward higher PCEs and practical applications. The theoretical PCE of fullerene-based OSCs is limited to ∼13% due to the relatively large energy losses. Many efforts have been dedicated to developing new acceptor systems beyond fullerenes, and some successful systems such as rylene diimides have achieved PCEs up to ca. 11%.In 2015, our group pioneered a new class of electron acceptors, fused-ring electron acceptor (FREA), as represented by the star molecule ITIC. The chemical features of FREAs include: (1) a modular structure, consisting of an electron-donating core, electron-withdrawing end groups, π-bridges, and side chains, which benefits molecular tailoring; (2) facile synthesis, purification, and scalability. The physical features of FREAs include: (1) a broad modulation range of absorption and energy levels; (2) strong absorption, especially in the 700-1000 nm region; (3) high electron mobility. The device features of FREAs include: (1) low voltage loss; (2) high efficiency; (3) good stability. The FREAs boosted PCEs of the OSCs up to 18% and initiated the transformation from the fullerene to nonfullerene era of this field. FREAs can also be used in PSCs as interfacial layers, electron transport layers, or active layers, improving both efficiency and stability of the devices. Beyond photovoltaic applications, FREAs can also be used in photodetectors, field-effect transistors, two-photon absorption, photothermal therapy, solar water splitting, etc.In this Account, we review the development of the FREAs and their applications in OSCs, PSCs, and other related fields. Molecular design, device engineering, photophysics, and applications of FREAs are discussed in detail. Future research directions toward performance optimization and commercialization of FREAs are also proposed.

Comparative analysis of energy matrices and enviro-economics for active and passive solar still

Due to the corresponding population increase, the demand of pure water keeps on rising day by day. The whole world is facing potable water stress. The solar distillation device plays a significant role as one of the key technology to development of fresh water. In this work, a suitable unit is being introduced that has been economical and eco-friendly. There has been presented the solar still behavior depending on energy matrices and enviro-economics. Active distillation technology has improved distillate performance by 119% compared to passive distillation device but also has substantial embodied energy (5602.94 kWh), as well as 102%, increased carbon reduction for both systems over 30 years of existence. The active device's carbon credit ranking is 102.4 points higher than the inactive distillation method and the passive model has shorter energy payback time for resources and higher processing performance for the life cycle i.e. conversion efficiency.

Assessment of double-pass pin finned solar air heater at different air mass ratios via energy, exergy, economic, and environmental (4E) approaches.

In this study, an assessment based on energy, exergy, economic, and environmental approaches on a double-pass (DP) solar air heater (SAH) having pin finned absorber at different air mass ratios up and down the absorber is investigated experimentally. Four air mass ratios are considered: (i) all the air mass flow passes up the absorber and returns to pass down the absorber (DP), (ii) 2/3 of the airflow passes up the absorber and returns to mix with the remainder of air to pass down the absorber (2/3 DP), (iii) the same as (ii) but 1/3 of the air passes up the absorber (1/3 DP), and (iv) all the air mass passes only down the absorber (single pass, SP). For all mass ratios, the performance of pin finned SAH (P_SAH) is compared with that of flat SAH (F_SAH). The results indicated that the air temperature rise and energy and exergy efficiencies of P_SAH are highly greater than those of F_SAH. The highest average thermal efficiency of F_SAH is 56.7% obtained at DP flow condition, whereas the highest value of P_SAH is 65.21% obtained at 2/3 DP with an increase of 17.6% compared with F_SAH. Also, P_SAH has higher average exergy efficiency of about 34.7% compared to F_SAH. Furthermore, P_SAH achieves energy payback time (EPBT) lower than that of F_SAH, while P_SAH has higher embodied energy. The findings indicated that F_SAH at SP airflow pattern has the maximum energy cost (0.0427$/kWh), whereas P_SAH at 2/3 DP airflow pattern achieves the minimum energy cost (0.037$/kWh). Finally, the proposed P_SAH system appears to be more viable from exergoeconomic and enviroeconomic approaches compared to F_SAH.

Energy, exergy, exergoeconomic and exergo-environmental analyses of a large scale solar dryer with PCM energy storage medium

In this paper, performance, exergoeconomic and exergo-environmental assessments of a large scale solar dryer with energy storage medium were presented. The usability of the system for high capacity industrial drying processes in terms of performance and energy use costs compared to existing drying techniques in the literature was clearly indicated in the study. Thus, exergoeconomic and environmental sustainability analyses were handled together for the first time, and all performance values of a high capacity industrial solar dryer were determined in detail. The system components were examined separately in exergoeconomic analysis. As a result of the exergoeconomic analysis, it was found that the fans had the highest cost of exergy destruction with $ 0.2286/h and the lowest exergy efficiency with 55.96%. Therefore, it was concluded that fans were the most important component need to be developed. When the system was considered in terms of environmental impact analysis, energy payback time was designated as approximately 6.82 years. CO2 mitigation for the expected lifetime of the system was calculated as 99.60 tones. The performed evaluations indicated that the developed system was a highly efficient technology for the industrial drying process both in terms of energy use performance and environmental sustainability.

Environmental assessment of transparent conductive oxide-free efficient flexible organo-lead halide perovskite solar cell

ABSTRACT Perovskite solar cells (PSCs), one of the third-generation photovoltaic (PV) technologies, have recently become a very popular topic in photovoltaic research. This technology, which is a candidate for commercialization in the future, needs to be evaluated from an environmental point of view. The amount of electricity consumption is the most important factor that directly determines the environmental impact values of photovoltaic cell manufacturing. Transparent conductive oxide (TCO) coated glass is one of the major contributors to electricity consumption in PSC architecture. It is therefore useful to investigate the environmental profile of TCO coated glass-free PSC architecture with conventional PVs. One of the solutions to this issue is manufacturing PSC on a flexible substrate. Flexible PVs are considered to be one of the most promising candidates for mass production with its advantages of low-temperature manufacturing, higher efficiency with a lower weight, portability, and compatibility with a roll to roll fabrication. In this work, we show that the environmental impacts of a representative PSCs with a flexible substrate. While the energy payback time (EPBT) of the flexible PSC is already competitive with commercial PVs, the device must reach a 25-year cell lifetime for its global warming potential (GWP) to reach a reasonable range.

Energy payback time analysis and return on investment of off-grid photovoltaic systems in rural areas of Tanzania

Owing to a vast land area, abundant solar radiation, and overseas support, the use of photovoltaics (PV) as a source of electricity is rapidly spreading in Sub-Saharan Africa. To understand the actual application situations, two cases of PV electricity generation systems in the rural areas of Tanzania were investigated via life cycle assessment. The energy payback time (EPBT) calculated from the utilisation of the PV systems, taking into consideration the inventory data of the International Energy Agency, revealed an unsatisfactory performance. Specifically, the EPBTs based on actual power generation at the sites greatly exceeded the expected value-based solar radiation calculations. At one site, the EPBT even exceeded the lifespan of the PV panel, indicating that energy recovery was impossible. With respect to the energy return on investment (EROI), it was evident that the income generated from the investments was insufficient to cover current operational costs, suggesting negative returns on investment. Conversely, diesel power generation appeared to be more suitable in these areas owing to the low and discontinuous demand for power. Furthermore, the operation of a more efficient PV system would require improved maintenance and management, as well as an increase in the demand for electricity.

Energy, exergy and enviro-economic assessment of productivity enhanced passive double sided vertical convection solar distiller for fresh water production

Vertical solar distiller’s productivity is similar to other available passive solar stills but it occupies less ground area. Hence, enhancing its productivity is of wide interest for researchers. In general, most of the enhancement techniques increase distiller’s capital cost, maintenance cost and distillate production cost which in turn hinder its real time applicability. Hence, enhancing distillate productivity by adopting techniques having minimal impact on distiller’s capital cost is an effective option to reduce distillate production cost and increase chance of acceptability among public. In this work, feed water supply rate has been selected as a tool for enhancing distillate productivity of double sided vertical convection solar distiller. Transient mathematical model of distiller is developed and simulated under the climatic condition of Chennai, India to study the impact of geometric parameters and feed water supply rate on its performance, economics and environmental benefits. Enhanced performance of the unit is observed for a vertical absorber area, gap and feed water supply rate of 3.0 m2, 0.05 m and 40.0 kg/d, respectively. Feed water supply rate below recommended value has positive impact on recovery ratio and negative impact on distillate production rate, energy and exergy efficiency. The unit generated annual average distillate yield of about 12.55 kg/d with recovery ratio, energy and exergy efficiency of 31.70%, 62.16% and 4.73%, respectively. Maximum distillate production cost of the unit is just Rs. 2.00/L (~0.03 USD/L). Maximum energy and finance payback time is within 1 Yr and 8 Yr, respectively. Moreover, its minimum assured emission mitigation potential for 20 Yr life time is about 69.36 tons of CO2, 498.70 kg of SO2 and 203.69 kg of NO. High yield, reasonable distillate production cost and environmental benefits make proposed improved vertical distiller a suitable candidate for potable water production.

Printed and hybrid integrated electronics using bio-based andrecycled materials\u2014increasing sustainability with greener materials andtechnologies

Printed and hybrid integrated electronics produced from recycled andrenewable materials can reduce the depletion of limited material resources whileobtaining energy savings in small electronic applications and their energy storage.In this work, bio-based poly(lactic acid) (PLA) and recycled polyethyleneterephthalate (rPET) were fabricated in film extrusion process and utilized as asubstrate in ultra-thin organic photovoltaics (OPV). In the device structure, metalsand metal oxides were replaced by printing PEDOT:PSS, carbon and aminoacid/heterocycles. Scalable, energy-efficient fabrication of solar cells resulted inefficiencies up to 6.9% under indoor light. Furthermore, virgin-PET was replacedwith PLA and rPET in printed and hybrid integrated electronics where surface-mountdevices (SMD) were die-bonded onto silver-printed PLA and virgin-PET films toprepare LED foils followed by an overmoulding process using the rPET and PLA. As aresult, higher relative adhesion of PLA-PLA interface was obtained in comparisonwith rPET-PET interface. The obtained results are encouraging from the point ofutilization of scalable manufacturing technologies and natural/recycled materials inprinted and hybrid integrated electronics. Assessment showed a considerable decreasein carbon footprint, about 10–85%, mainly achieved through replacing of silver,virgin-PET and modifying solar cell structure. In outdoor light, the materials withlow carbon footprint can decrease energy payback times (EPBT) from ca. 250 days tounder 10 days. In indoor energy harvesting, it is possible to achieve EPBT of lessthan 1 year. The structures produced and studied herein have a high potential ofproviding sustainable energy solutions for example in IoT-relatedtechnologies.

Application design and assessment of a novel small-decentralized solar distillation device based on energy, exergy, exergoeconomic, and enviroeconomic parameters

In this paper, a novel small-decentralized desalination device is presented for increasing the temperature difference between brackish water and glass cover, so as to enhance the solar still’s freshwater productivity. This novel solar still device is based on installing a lens in front of the single slope solar still, and two lenses on still’s both sides, and a reflector over the back side of the solar still. The main objective of such novel still is to concentrate sunrays at the still’s bottom basin, through the refraction function of Fresnel lens. Furthermore, this novel still makes the reflector transferring its reflected sunrays to the solar still’s basin. Experiments are conducted under the climate conditions in Hangzhou city, China, for testing the novel still’s operational performance, and internal heat and mass transfer characteristics. Assessment of the novel still’s feasibility is performed based on energy, exergy, exergoeconomic, and enviroeconomic methodologies, as well as energy payback time. Results show that the productivity of novel still is 32% higher than that of conventional still, and novel solar still enhances the average hourly energy efficiency by 97.73%, compared to conventional solar still. While, the corresponding value of hourly exergy efficiency is also enhanced by 43.713%. Due to the higher energy and exergy outputs of novel still throughout its lifetime, the novel solar still proposed in this study mitigates more CO2 compared to the conventional still. Overall, incorporation three lenses and one reflector with the still is found promising in terms of freshwater yield, cost, and energy payback time compared to conventional one. Exergoeconomic and environmental parameters of the novel solar still are found more effective compared to the conventional one.

Productivity, exergy, exergoeconomic, and enviroeconomic assessment of hybrid solar distiller using direct salty water heating.

In this work, experimental work is presented on the performance of a hybrid solar distiller comprising solar still (SS) combined with parabolic trough solar collector (PTSC) using direct heating of salty water by the collector. In this technique, the salty water supplied to the SS is heated by passing it directly through the parabolic receiver without using heat transfer mediums that reduce the system efficiency. The study is carried out at different salty water depths inside the SS basin under hot climate conditions of Upper Egypt. The system performance is compared with a previous system using oil as a heat transfer medium between PTSC and still (indirect heating). The advantages of this technique are its ability to reduce initial salty water depth in the basin and avoid using the pumping system and heat exchanger compared to the direct heating. The performance of the proposed system is evaluated based on productivity, energy payback time (EPBT), exergy, enviroeconomic, and exergoeconomic methodologies. Findings illustrate that the present system rises the energy efficiency by about 12%, 27.5%, and 46% and the system exergy efficiency by about 14%, 30%, and 49% at salty water depth 15 mm, 10 mm, and 5 mm in the basin compared with the indirect heating system. Moreover, using this technique of salty water heating reduces the production cost of freshwater by about 71% compared with the direct heating system. The exergoeconomic and enviroeconomic parameters of the direct heating mechanism are more effective compared with those of the indirect heating mechanism.

Energy, exergy and environmental assessment of solar still with solar panel enhanced by porous material and saline water preheating

An assessment of hybrid solar desalination system consists of solar panel integrated with single slope solar distiller improved by salty water preheating and porous material via productivity, energy, exergy, exergoeconomic and exergoenvironmental is performed under metrological conditions of Alexandria, Egypt. Water preheating is performed by passing it over the solar panel front surface before it enters the still basin, which is also used as solar panel cooler. The panel integration is performed by installing it directly over the still back wall. Solar panel power is used to heat up further the salty water. Moreover, the impact of utilizing black steel wool fibers in the still basin on the system performance is studied. Results illustrate that preheating 40%, 50%, and 60% of the salty water rises solar desalination system freshwater yield by 10.4%, 15.5%, and 20.9%, energy efficiency by 8.2%, 13% and 20% and exergy efficiency by 26.86%, 33.51%, and 60.64%, respectively. Using black steel wool fibers increases conventional solar still and solar desalination system production without and with 60% preheating by 17.8%, 13.7%, and 11.8%, energy efficiency by 13.58%, 9.73%, and 13.5% and exergy efficiency by 16.51%, 10.27%, and 32.45%, respectively. Solar desalination system with black steel wool fibers and 60% of water preheating achieves the highest performance based on freshwater yield, cost, energy payback time, exergoeconomic, exergoenvironmental and exergoenviroeconomic parameters. With these positive results and the available solar energy in Egypt, the current system can be a promising nation strategy in saline water desalination and power production.

Application of organic photovoltaic materials (OPV) as greenhouse roof structures: A review

Organic Photovoltaic (OPV), as a third-generation PV technology, is becoming an appropriate substance used for greenhouse roofing structures. Semi-transparent OPV has a variety of merits such as low weight, flexibility, low environment impact and short energy payback time. Besides, it can harness larger amounts of sunlight as means of a very strong light absorbent material. This study shares some of the latest research which examines the feasibility of using semi-transparent, flexible organic photovoltaic (OPV) modules as greenhouse shading material. By using such modules, it may be possible to utilize the existing greenhouse-based agricultural areas for electricity production. The concept projects OPV modules to shade greenhouses and reduces excess solar energy which may result in reducing internal surrounding heat thus helps to mitigate the control environment. This will furthermore control plant heat stress which is one of the most important factors for plant growth. Some conclusion on the quality and quantity of plants with respect to the energy consumption in the greenhouse are also discussed.

Environmental impact of a 290.4kWp grid-connected photovoltaic system in Kocaeli, Turkey.

This paper examines the environmental impact of a grid-connected PV system in Kocaeli, Turkey, supported by East Marmara Development Agency to contribute local economic and environmental sustainability goals. For this purpose, energy payback time and greenhouse payback time analysis is carried out in terms of calculated total embodied data and measured annual operation data. The results indicate that the system spends approximately 12.68% of its lifetime to payback its total embodied energy and 10.67% to save its total embodied greenhouse gas emissions.Graphic abstract

Energy metrics assessment of a photovoltaic thermal air collector (PVTAC): a comparison between flat and wavy collector

ABSTRACT In this paper, the performances of two different configurations of the PVT air collector (PVTAC) were studied and compared with respect to three energy matrices: energy payback time, electricity production factor, and life-cycle conversion efficiency. Geometrically, both configurations are similar except one equipped with a flat plate collector (PVTACF) and other with a wavy plate collector (PVTACW). An experimental investigation was performed for both the models, located at Silchar (Latitude: 24.8333° N and Longitude: 92.7789° E) over a period of 1 year (May 2017 to April 2018). Initially, airflow velocity was varied between 1–3 m/s and ideal airflow velocity (2.5 m/s) was identified. The yearly energetic and exergetic performance was studied and presented. The overall annual energy and exergy of the PVTACW were achieved by 8.2% and 2.3% higher than the PVTACF. The energy payback time, electricity production factor, and life-cycle conversion efficiency of the PVTACW were also achieved better than the PVTACF. The study provides useful information on the energetic performance and environmental impact of the PVTAC system under North-East Indian climatic conditions.