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Energy Payback Time of a Rooftop Photovoltaic System in Greece
摘要： Life Cycle Analysis (LCA) is an important tool to quantitatively assess energy consumption and environmental impact of any product. Current research related to energy consumption in buildings moves towards Nearly Zero Energy Building (NZEB). In such a building, an important issue concerns the energy production by renewable sources, including on-site production. The most feasible way to achieve renewable energy utilization in a building level in Greece is by using rooftop Photovoltaic (PV) systems, also promoted in the last decade by the national legislation concerning energy conservation measures. Apart from cost-related issues and payback times, Embodied Energy (EE) and Embodied CO2 (ECO2) emissions have also to be considered against the anticipated corresponding savings. Using a particular PV system as a case study, its basic constitutive materials are determined and their masses are calculated. Embodied energy values are estimated by using embodied energy coefficients available in the international literature. Considering a specific geographic location in Greece for the building on which the PV is installed, the annual energy generated by the system is estimated based on its performance data and curves. The Energy and CO2 Payback Times (EPBT and CO2PBT) are estimated and assessed, as well as future work is suggested.
关键词： Photovoltaic systems,CO2 Payback Time,Embodied CO2,Energy Payback Time,Life Cycle Analysis,Nearly Zero Energy Building,Embodied Energy
更新于2025-09-23 15:21:01
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Storage systems for building-integrated photovoltaic (BIPV) and building-integrated photovoltaic/thermal (BIPVT) installations: Environmental profile and other aspects
摘要： In recent years there has been an increasing interest in Building-Integrated Photovoltaic (BIPV) and Building-Integrated Photovoltaic/Thermal (BIPVT) systems since they produce clean energy and replace conventional building envelope materials. By taking into account that storage is a key factor in the effective use of renewable energy, the present article is an overview about storage systems which are appropriate for BIPV and BIPVT applications. The literature review shows that there are multiple storage solutions, based on different kinds of materials (batteries, Phase Change Material (PCM) components, etc.). In terms of BIPV and BIPVT with batteries or PCMs or water tanks as storage systems, most of the installations are non-concentrating, fa?ade- or roof-integrated, water- or air-based (in the case of BIPVT) and include silicon-based PV cells, lead-acid or lithium-ion batteries, paraffin- or salt-based PCMs. Regarding parameters that affect the environmental profile of storage systems, in the case of batteries critical factors such as material manufacturing, accidental release of electrolytes, inhalation toxicity, flammable elements, degradation and end-of-life management play a pivotal role. Regarding PCMs, there are some materials that are corrosive and present fire-safety issues as well as high toxicity in terms of human health and ecosystems. Concerning water storage tanks, based on certain studies about tanks with volumes of 300 L and 600 L, their impacts range from 5.9 to 11.7 GJprim and from 0.3 to 1.0 t CO2.eq. Finally, it should be noted that additional storage options such as Trombe walls, pebble beds and nanotechnologies are critically discussed. The contribution of the present article to the existing literature is associated with the fact that it presents a critical review about storage devices in the case of BIPV and BIPVT applications, by placing emphasis on the environmental profile of certain storage materials.
关键词： ecotoxicity,Building-Integrated Photovoltaic/Thermal (BIPVT),embodied energy,Human toxicity,Life Cycle Assessment (LCA),CO2 emissions,Building-Integrated Photovoltaic (BIPV),Storage materials
更新于2025-09-19 17:13:59
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Effect of adjacent shading on the energy and environmental performance of photovoltaic glazing system in building application
摘要： Photovoltaic (PV) system is a commonly adopted renewable energy system in building application. In most of the assessments on PV system, there is no consideration on adjacent shading effect cast by surrounding buildings which may lead to over-estimation of PV energy generation and inaccurate calculation of energy payback time (EPBT). This paper investigates the effect of adjacent shading on energy generation and EPBT of PV system. A survey had been conducted to identify and select 25 existing commercial buildings with different degrees of adjacent shading (expressed in terms of sky view factors (SVF), ranging from 0.16 to 0.95) and orientations. Through computer simulations using EnergyPlus, it reveals the significance of adjacent shading effect on the PV energy generation as well as EPBT of building-integrated PV glazing system for the 25 selected buildings, in terms of two ratios, namely PV electricity energy ratio (0.18e0.84) and energy payback time ratio (1.17e5.74). Moreover, a correlation between SVF and PV electricity energy ratio was established (PVEE Ratio ? 0.3867 SVF2 t 0.4176 SVF t 0.0975) with which building professionals can evaluate the PV energy generated and EPBT of a building-integrated PV glazing system in building application, under adjacent shading effect.
关键词： Adjacent shading effect,Sky view factor,Photovoltaic system in building application,Embodied energy in photovoltaic system,Energy payback time
更新于2025-09-16 10:30:52