| 1. |
- Johansson, F., et al.
(författare)
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3D-thermal modelling of a bifacial agrivoltaic system: a photovoltaic module perspective
- 2022
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Ingår i: Energy Nexus. - : Elsevier BV. - 2772-4271. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a 3D computational fluid dynamic model to evaluate the temperature distribution and energy performances of a vertical bifacial photovoltaic module for agrivoltaic applications. This last is compared to a conventionally tilted bifacial photovoltaic module for ground-mounted applications. The simulations are performed in SolidWorks Flow Simulation® and validated with measured data gathered from the first experimental agrivoltaic system in Sweden. Additionally, four more simulations scenarios were defined to compare the performances of vertically mounted and conventionally tilted bifacial photovoltaic modules under different operating conditionsThe validation of the computational fluid dynamic model shows that the model tends to underestimate the readings performed with the thermal camera in the order of 3°C to 4°C for the vertical bifacial PV module. The comparison of the results obtained from the computational fluid dynamic model with existing models available in literature shows a good agreement. The comparison of the heat distribution from the computational fluid dynamic model and the thermal images also shows a good agreement. In all the scenarios investigated, the vertical bifacial photovoltaic module's overall efficiency was higher than that of the ground-mounted module due to lower average operating temperatures. The use of the computational fluid dynamic approach for studying the performance of a single photovoltaic module showed promising results that can be extended to study the system performance and microclimatic conditions.
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| 2. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
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A gridded optimization model for photovoltaic applications
- 2020
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Ingår i: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 202, s. 465-484
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to develop a gridded optimization model for studying photovoltaic applications in Nordic countries. The model uses the spatial and temporal data generated by the mesoscale models STRANG and MESAN developed by the Swedish Meteorological and Hydrological Institute. The model is developed based on the comparison between five irradiance databases, three decomposition models, two transposition models, and two photovoltaic models. Several techno-economic and environmental aspects of photovoltaic systems and photovoltaic systems integrated with batteries are investigated from a spatial perspective. CM SAF SARAH-2, Engerer2, and Perez1990 have shown the best performances among the irradiance databases, and decomposition and transposition models, respectively. STRANG resulted in the second-best irradiance database to be used in Sweden for photovoltaic applications when comparing hourly global horizontal irradiance with weather station data. The developed model can be employed for carrying out further detailed gridded techno-economic assessments of photovoltaic applications and energy systems in general in Nordic countries. The model structure is generic and can be applied to every gridded climatological database worldwide.
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| 3. |
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| 4. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
-
Evaluation of the first agrivoltaic system in Sweden
- 2023
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Photovoltaic (PV) systems in Sweden have primarily been seen as an energy efficiency measure to reduce the amount of purchased electricity for buildings, both residential and commercial. Only recently utility-scale solar systems have begun to increase their share of the solar market to support national energy and emissions targets. Due to the economies of scale, conventional ground-mounted PV (CGMPV) installations represent the best solution for producing electricity at the lowest specific initial investment costs. This relatively new solar market segment, with large-scale ground-mounted solar farms on agricultural land, has faced several challenges with the permitting process. Agricultural land that is suitable for cultivation is of "national importance" according to the Swedish Environmental Code. Cultivable agricultural land may be exploited for other purposes on a permanent basis only if it is necessary to satisfy essential societal interests and there is no other possible land to use within the area in question. Traditionally, ground-mounted solar farms have increased competition for land resources for food production and drawn criticism in the so-called "food-versus-fuel (electricity)" debate over whether agricultural land should be used for electricity generation or food production. Agrivoltaic (APV) systems represent an intelligent solution to avoid land use competition by combining arable farming and electricity production on the same agricultural land. The main objective of this project was to study how APV systems perform from an energy, agricultural and economic perspective compared to CGMPV systems and agriculture production. The project aimed to highlight advantages and disadvantages of APV systems at northern latitudes with an energy-food-water perspective. The aim was pursued by establishing an APV test site, the first APV system in Sweden, monitoring its performance both from an energy and agricultural point of view, and developing new techno-economic models. Data from the APV test site were used to better understand how APV systems at northern latitudes affect: 1) the efficiency of the solar modules; 2) crop productivity, and 3) the financial return for ground-based solar PV systems. The first agrivoltaic system in Sweden has been built on a permanent ley grass field, at Kärrbo Prästgård, Västerås, and research activities have been carried out on the ley grass during 2021 and 2022. As in previous research studies in other countries, we defined three sub-fields: 1) a sub-field is covered only by the ley grass (reference area), 2) a sub-field is a CGMPV system 11.8 kWp solar PV system with two rows of solar modules with a 30° tilt and 3) the last subfield is a 22.8 kWp APV system with three rows of vertically mounted solar modules, with ley grass between the modules. This field set-up allowed for comparisons between practices (agriculture and electricity generation) and technologies (CGMPV systems versus APV systems). The calculated specific electricity production during a typical meteorological year for the APV system and the CGMPV system was 1,067 kWh/kWp/year and 1,116 kWh/kWp/year, respectively. Nevertheless, the APV system tends to have higher efficiency than the CGMPV systems due to the solar irradiation patterns on the solar cell surfaces and wind cooling of the PV modules. The main results of the project in terms of shadow effects on the ley grass showed that the APV system did not significantly affect the productivity of the forage grass in 2021-2022. There was no statistically significant difference between the yield of the samples taken in the APV system and the reference area. Even so, the yield per hectare is reduced by approximatively 10%, when the distance between the vertically mounted solar modules is 10 meters, due to the area under the solar modules that cannot be mechanically harvested. The measurements performed at the test site allowed us to validate the earlier developed model for both electricity production and the effects of shading on crop production. Having a model to assess crop yields under APV systems is of utmost importance to be able to pre-assess the system's effects on food production, which is one of the main goals of APV system regulations worldwide. From an economic perspective, APV systems cannot compete with CGMPV systems due to lower electricity production per hectare, lower density of the solar modules per hectare, and higher investment costs per hectare. Nevertheless, APV systems can be the solution to overcome the legal obstacles that prohibit or hinder the use of agricultural land for electricity generation with PV systems.
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| 5. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
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Experimental results, integrated model validation, and economic aspects of agrivoltaic systems at northern latitudes
- 2024
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 437
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Tidskriftsartikel (refereegranskat)abstract
- Agrivoltaic systems, which allow the coexistence of crop and electricity production on the same land, are an integrated water–energy–food nexus solution that allows the simultaneous attainment of conflicting Sustainable Development Goals. This study aims to analyse experimental results on the responses of ley grass yield and quality to shadings in the first agrivoltaic system in Sweden. It also aims to validate an integrated modelling platform for assessing agrivoltaic systems' performances before installation. An economic analysis is carried out to compare the profitability of agrivoltaic versus conventional ground-mounted photovoltaic systems and, using a Monte Carlo Analysis, to identify the parameters that most affect the profitability. Despite the agrivoltaic systems’ supporting structures and photovoltaic modules producing an average ∼25% reduction in photosynthetically active radiation at ground level, no statistically significant difference was observed between the yield of the samples under the agrivoltaic system compared to the yield of the samples in the reference area. The agrivoltaic system attained land equivalent ratios of 1.27 and 1.39 in 2021 and 2022, respectively. The validation results of the integrated modelling platform show that the sub-model concerning the crop yield response to shading conditions tends to underestimate ∼7% the actual average crop yield under the agrivoltaic system. The results of the economic analysis show that, from a net present value perspective, agrivoltaic systems have a profitability that is ∼30 times higher than a conventional crop rotation in Sweden.
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| 6. |
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| 7. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
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Li-ion batteries for peak shaving, price arbitrage, and photovoltaic self-consumption in commercial buildings : A Monte Carlo Analysis
- 2021
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 234
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the benefits of introducing Li-ion batteries as energy storage unit in the commercial sector by considering a representative building with a photovoltaic system. Only the costs and revenues related to the installation and operation of the battery are considered in this study. The operational strategy of the battery consists in balancing the following processes through day-ahead forecasts for both electricity consumption and photovoltaic production: shaving a targeted peak, performing price arbitrage, and increasing photovoltaic selfconsumption. By reviewing the electricity price cost for commercial buildings from several companies around the world, a general electricity price structure is defined. Afterwards, a Monte Carlo Analysis is applied for three locations with different solar irradiation levels to study the impact of climate, electricity price components, and other seven sensitive parameters on the economic viability of Li-ion batteries. The Monte Carlo Analysis shows that the most sensitive parameters for the net present value are the battery capacity, the battery price, and the component of the electricity price that relates to the peak power consumption. For Stockholm, one of the investigated locations, the corresponding Pearson correlation coefficients are -0.67, -0.66, and 0.19 for the case were no photovoltaic system is installed. For the considered battery operational strategies, the current investment and annual operation costs for the Li-ion battery always lead to negative net present values independently of the location. Battery prices lower than 250 US$/kWh start to manifest positive net present values when combining peak shaving, price arbitrage, and photovoltaic self-consumption. However, the integration of a photovoltaic system leads to a reduced economic viability of the battery by reducing the revenues generated by the battery while performing peak shaving.
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| 8. |
- Campana, Pietro Elia, 1984-, et al.
(författare)
-
Optimisation of vertically mounted agrivoltaic systems
- 2021
-
Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 325
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Tidskriftsartikel (refereegranskat)abstract
- Agrivoltaic systems represent a key technology for reaching sustainable development goals, by reducing the competition of land used for food versus land used for electricity. Moreover, agrivoltaic systems are at the centre of the nexus between electricity production, crop production, and irrigation water savings. In this study, an optimisation model for vertically mounted agrivoltaic systems with bifacial photovoltaic modules is developed. The model combines three main sub-models: solar radiation and shadings, photovoltaics, and crop yield. Validation of the sub-models is performed showing good agreement with measured data and commercial software. The optimisation model is set as multi objective to explore the trade-offs between competing agrivoltaic key performance indicators. Oats and potatoes are used as reference crops in this study. The results show that the row distance between bifacial photovoltaic module structures significantly affects the photosynthetically active radiation distribution. The resulting crop yield of oats and potato is reduced by about 50% as row distance decreases from 20 m to 5 m. The implementation of an agrivoltaic system for the investigated crops at the chosen location shows a land equivalent ratio above 1.2, which justifies the use of the technology for reaching national sustainability goals.
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| 9. |
- Elkadeem, M. R., et al.
(författare)
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Agrivoltaic systems potentials in Sweden : A geospatial-assisted multi-criteria analysis
- 2024
-
Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 356
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Tidskriftsartikel (refereegranskat)abstract
- Agrivoltaic systems represent an intelligent solution combining electricity production from solar photovoltaic technology with agricultural production to avoid land use conflicts. Geographic Information System technologies can support the implementation and spread of agrivoltaic systems by identifying the most suitable areas using useful spatially explicit information concerning techno-agro-socio-economic criteria. In this study, we have developed a procedure to identify and classify suitable areas for agrivoltaic systems in Sweden. An Ordinal Priority Approach based multi-criteria decision-making algorithm is established to calculate the weights of the selected evaluation criteria through expert interviews. The land use data refers to the Corine Land Cover 2018 product. The results show that about 8.6% of the Swedish territory, approximately 38,485 km2, is suitable for installing agrivoltaic systems. Among this area, about 0.2% is classified as “excellent”, about 15% as “very good”, about 72% as “good”, about 13% as “moderate”, and about 0.1% as “poor”. Most “excellent”-classified areas are in Kalmar, Skåne, and Gotland. In contrast, most “very good” sites are in Skåne, Kalmar, and Östergötland. By deploying vertically mounted agrivoltaic systems with bifacial photovoltaic modules, the total potential installed capacity for “excellent” areas is about 2.5 GWp, while for areas classified “excellent” and “very good” is about 221 GWp. The total “excellent” areas can potentially supply about 2.4 TWh of electricity against the electricity consumption in 2021 of about 143 TWh. On the other hand, the land classified as “excellent” and “very good” could potentially provide about 207 TWh. The County of Västra Götaland shows the greatest potentials in terms of total potential electricity supply from agrivoltaic systems with about 227 TWh, followed by Skåne with a total potential of 206 TWh.
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| 10. |
- Lu, Silvia Ma, et al.
(författare)
-
Photosynthetically active radiation separation model for high-latitude regions in agrivoltaic systems modeling
- 2024
-
Ingår i: Journal of Renewable and Sustainable Energy. - 1941-7012. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetically active radiation is a key parameter for determining crop yield. Separating photosynthetically active radiation into direct and diffuse components is significant to agrivoltaic systems. The varying shading conditions caused by the solar panels produce a higher contribution of diffuse irradiance reaching the crops. This study introduces a new separation model capable of accurately estimating the diffuse component from the global photosynthetically active radiation and conveniently retrievable meteorological parameters. The model modifies one of the highest-performing separation models for broadband irradiance, namely, the Yang2 model. Four new predictors are added: atmospheric optical thickness, vapor pressure deficit, aerosol optical depth, and surface albedo. The proposed model has been calibrated, tested, and validated at three sites in Sweden with latitudes above 58 °N, outperforming four other models in all examined locations, with R2 values greater than 0.90. The applicability of the developed model is demonstrated using data retrieved from Sweden's first agrivoltaic system. A variety of data availability cases representative of current and future agrivoltaic systems is tested. If on-site measurements of diffuse photosynthetically active radiation are not available, the model calibrated based on nearby stations can be a suitable first approximation, obtaining an R2 of 0.89. Utilizing predictor values derived from satellite data is an alternative method, but the spatial resolution must be considered cautiously as the R2 dropped to 0.73.
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| 11. |
- Ma Lu, Silvia, et al.
(författare)
-
Photosynthetically active radiation decomposition models for agrivoltaic systems applications
- 2022
-
Ingår i: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 244, s. 536-549
-
Tidskriftsartikel (refereegranskat)abstract
- Decomposition models of solar irradiance estimate the magnitude of diffuse horizontal irradiance from global horizontal irradiance. These two radiation components are well known to be essential for predicting the performance of solar photovoltaic systems. In open-field agrivoltaic systems (i.e., the dual use of land for both agricultural activities and solar power conversion), cultivated crops receive unequal amounts of direct, diffuse, and reflected photosynthetically active radiation (PAR). These uneven amounts depend on where the crops are growing due to the non-homogenous shadings caused by the presence of the installed solar panels (above the crops or vertically mounted). It is known that, per unit of total PAR, diffuse PAR is more efficient for canopy photosynthesis than is direct PAR. For this reason, it is essential to estimate the diffuse PAR component when agrivoltaic systems are being assessed, in order to properly predict the crop yield. Since PAR is the electro-magnetic radiation in the 400-700 nm waveband that can be used for photosynthesis by the crops, several stand-alone decomposition models typically used to split global horizontal irradiance are selected in this study to decompose PAR into direct and diffuse. These models are applied and validated in three locations in Sweden (Lanna, Hyltemossa and Norunda) using the coefficients stated on the models' original publications and locally fitted coefficients. The results showed weaker performances in all stand-alone models for non-locally fitted coefficients (nRMSE ranging from 27% to 43%). However, performances improve with re-parameterization, with a highest nRMSE of 35.24% in Lanna. The Y(ANG)2 decomposition model is the best-performing one, with the lowest nRMSE of 23.75% in Norunda when applying re-estimated coefficients. Country level sets of coefficients for the best-performing models (Y(ANG)2 and STARKE) are given after parameterization using combined data for all three locations in Sweden. These Sweden-fitted models are tested and show an nRMSE of 25.08% (Y(ANG)2) and 28.60% (STARKE). These results can be used to perform estimations of the PAR diffuse component in Sweden wherever ground measurements are not available. The overall methodology can be similarly applied to other countries.
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| 12. |
- Ma Lu, Silvia, et al.
(författare)
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Validation of Vertical Bifacial Agrivoltaic and Other Systems Modelling : Effect of Dynamic Albedo on Irradiance and Power Output Estimations
- 2023
-
Konferensbidrag (refereegranskat)abstract
- In agrivoltaic systems combining solar photovoltaic and agricultural activities, ground albedo is mainly characterized by the crop and its seasonal variations. This study examines the effects of using fixed, satellite-derived, and hourly measured albedo on the performance of a vertical bifacial system and a 1-axis tracking system using a bifacial photovoltaic model (AgriOptiCE®). The model is developed with Matlab® and partially based on the open-source package pvlib. AgriOptiCE® is firstly validated by comparing estimated front and rear irradiances with on-site measurements for specific periods from a 1-axis tracker site in Golden, USA and a vertical agrivoltaic system in Västerås, Sweden. Furthermore, photovoltaic system power output estimations using AgriOptiCE® are also validated for the vertical agrivoltaic system and the conventional ground-mounted fixed-tilt system at the same location. The validations demonstrate the high accuracy of the proposed model in estimating front and rear irradiances and power output, obtaining R2 > 0.85 for all the studied cases. The study results indicate that measured albedo provides the highest accuracy, while satellite- derived albedo has poorer results due to the broader spatial, temporal, and spectral resolution. Fixed albedo is not recommended for yearly assessment of bifacial PV systems because it cannot account for snow events and daily variations, resulting in lower overall accuracy.
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| 13. |
- Molin, Elin, et al.
(författare)
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Experimental yield study of bifacial PV modules in Nordic conditions
- 2018
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Ingår i: IEEE Journal of Photovoltaics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2156-3381 .- 2156-3403. ; 8:6, s. 1457-1463
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Tidskriftsartikel (refereegranskat)abstract
- This study reports on the first full-year field study in Sweden using bifacial photovoltaic modules. The two test sites are located on flat roofs with a low albedo of 0.05 in Linköping (58 °N) and were studied from December 2016 to November 2017. Site 1 has monofacial and bifacial modules with a 40° tilt facing south, which is optimal for annual energy yield for monofacial modules at this location. Site 2 has monofacial 40° tilt south-facing modules and bifacial vertical east–west orientated modules. The annual bifacial energy gain (BG E ) was 5% at site 1 and 1% at site 2 for albedo 0.05. The difference in power temperature coefficients between bifacial and monofacial modules was estimated to influence BG E by +0.4 and +0.1 percentage points on site 1 and 2, respectively. A higher albedo could be investigated on a sunny day with fresh snow for the bifacial east–west modules. The specific yield was 7.57 kWh/kW p , which was a yield increase of 48% compared with tar paper at similar solar conditions.
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| 14. |
- Stridh, Bengt, Universitetslektor, 1957-, et al.
(författare)
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Development of BIPV Business Cases : Guide for stakeholders
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Over recent years, continuous price decreases of PV system components and technological improvements, leading to better efficiency and reliability, contributed to reinforce the attractiveness of this technology. This is a trend that also benefitted building-integrated photovoltaic (BIPV) systems, which have become more affordable. In addition, it appears that the sector is dynamic and able to gain traction, as the significant number of competitors on the market tends to demonstrate. Nevertheless, in spite of this multiplicity of existing integrated PV products and the apparent market opportunities, deployment of BIPV solutions remains limited. Among the explanatory factors for this observation, one can cite the lack of appropriate business models or, at least, the lack of business models with a clear value proposition for BIPV systems.Possible drivers for BIPV system installation are crucial in order to define a value proposition that is as efficient as possible, as well as a business model. To refine the understanding of these drivers, the first chapter of this report explores these aspects in depth in section 2. The value of BIPV is not purely the economic value from electricity generation; it can also be connected to contributing to the local transition of the energy system, locally produced electricity, sustainability and marketing. The value of BIPV can be leveraged by companies willing to highlight a vision or mission that reaches beyond profit-oriented goals. Also, as a building component, BIPV can provide the same or better building functionalities as other building materials and help at the same time to meet legal requirements in terms of energy performance of buildings. Finally, the ability of BIPV solutions to improve real estate value is evoked as well, increasing the attractiveness of such investments, provided that the involved stakeholders can take advantage of this value.Different stakeholders involved in the business models are highlighted. They constitute the focus of section 3, in which they are characterized by their specific interests and role in BIPV projects, to guarantee the efficiency of the designed business models.In the following section, the framework used to conduct the analysis and frame the discussion on business models is presented. It is directly followed by the main section of the report, where examples of business models related to different building typologies and central stakeholders, i.e. product or service providers, are presented. The first examples are based on projects for residential buildings, while the second is based on a product for commercial buildings and the third is a service for commercial buildings. Each example is followed by discussions regarding key values and stakeholders, the main touchpoints of the business model as well as the pitfalls to avoid. Remaining challenges to the implementation of such business models are also listed. This section demonstrates that BIPV business models, with various degrees of innovation, can be designed, even if implementation remains to be tested for some of them. Specific business models can be developed with the help of, or with ideas from, the generic versions in this report.Ultimately, the purpose of this report is to provide a guide for design and application of business models to be used by stakeholders involved in the design process, for example existing and new businesses in the energy and construction sectors or housing and real estate companies. The guide aims at helping by highlighting the critical points of attention, allowing stakeholders to ask the relevant questions, but also by providing some ideas and answers on business model design and on how to maximize value creation and recognition. Some technical aspects are included but they are not the focus of this report.
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| 15. |
- Stridh, Bengt, Universitetslektor, 1957-, et al.
(författare)
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Förbättrad beräkning av solelproduktion i Sverige
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nordligt läge med lägre solstrålning än exempelvis södra Europa och förhållandevis lågt elpris gör att noggranna förutsägelser av energiutbyte från solcellsanläggningar är av stor vikt när man gör investeringskalkyler i Sverige. Noggrannare beräkningar av förväntad solelproduktion ger mindre ekonomisk osäkerhet, vilket resulterar i en mer resurseffektiv utveckling. Val av meteorologiska data och beräkningsmetod för kalkyler av solelproduktion är därför av stor vikt.En fråga är därför vilket simuleringsprogram för solelproduktion som är bäst att använda i Sverige. OptiCE, Polysun, PVsyst och PV*SOL med programmens meteorologiska databaser visade sig här vara relativt likvärdiga för Stockholm, Norrköping och Visby. Överensstämmelsen är relativt god med de uppmätta värdena för solelproduktion under 2019, med skillnader på mindre än ±5%. Men de ger alla 13%-15% för höga värden för Kiruna. PVGIS med databas ERA5 ger lite större avvikelser för Stockholm, Norrköping och Visby än ovan nämnda program men ger ett värde nära det uppmätta under 2019 i Kiruna. SAM och PVGIS med databaserna SARAH eller COSMO ger större avvikelser än ovan nämnda program. Då SARAH i en jämförande studie hade bäst noggrannhet är det tänkbart att beräkningarna i PVGIS skulle kunna förbättras genom att välja SARAH i kombination med ett lägre värde än grundinställningen 14% för systemförluster.Den största osäkerheten vid uppskattning av solcellssystems elproduktion kommer från solstrålningsdata. Genom att förbättra solstrålningsdata och göra dem allmänt tillgängliga hjälps investerare att fatta beslut med minskad osäkerhet. Det finns behov av en branschstandard för solstrålningsdata i Sverige. En vidareutveckling av STRÅNG-modellen för solstrålningsdata är önskvärd. Ett standardförfarande hur man beräknar inverkan av skuggning skulle vara värdefullt, då skuggning vid sidan om val av solstrålningsdatabaser kan ha en stor inverkan på utbytet av solel.Solstrålningsklimatet kan förändras över tid, vilket man kan se i uppmätt solstrålning för Sverige. I framtiden kan även pågående klimatförändring ha betydelse för solinstrålning och därmed solenergiproduktion. Data för solstrålning, vind, temperatur och albedo från klimatscenarion för två tidsperioder (2030-2065 och 2066-2095) användes för att uppskatta hur solelproduktionen kan komma att påverkas. Resultatet pekar på att solelproduktionen minskar något men att förändringen endast är statistiskt signifikant i det scenario som representerar fortsatt höga koldioxidutsläpp och då endast för norra Sverige under den senare tidsperioden. Sett över hela landet beräknas förändringen för denna period hamna mellan -9% (10:e percentilen) och -2% (90:e percentilen) med medelvärde på ca -6%.De kartor för Sverige för optimerade lutningar, solstrålning och solelproduktion som tagits fram med den utvecklade modellen OptiCE är ett verktyg för att bättre förstå, utforma och förbättra installationer av solcellssystem i Sverige.Bland de undersökta modellerna för uppdelning av global horisontell solstrålning i diffus och direkt strålning för att ta fram egna solstrålningsdata för användning i simuleringsprogram är slutsatsen att för timvärden är Engerer2 eller Paulescu och Blaga lämpliga val. För 1-minutvärden visar Yang2 bäst prestanda.
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| 16. |
- Stridh, Bengt, Universitetslektor, 1957-, et al.
(författare)
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Uncertainties in Yield Assessments and PV LCOE : Report IEA-PVPS T13-18:2020 November 2020
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Yield assessments (YA) and Long-Term Yield Predictions (LTYP) are a prerequisite for business decisions on long term investments into photovoltaic (PV) power plants. Together with cost data (CAPEX, OPEX and discount rate), the output of a YA and LTYP (utilisation rate, performance loss rate and lifetime) provides to the financial investors the parameters needed for the calculation of the Levelised Cost of Electricity (LCOE) and to assess the cash flow model of an investment with relative Internal Rate of Return (IRR) and Net Present Value (NPV).YA and LTYP outputs should be provided with a related exceedance probability. This gives the right tool to stakeholders involved in PV projects to take the best decision in terms of riskaversion. A reduction in the uncertainty of the energy yield can lead to higher values for a given exceedance probability and hence a stronger business case. Various efforts in the literature show the importance of having a common framework that can assess the impact of technical risks on the economic performance of a PV project.The most important parameter influencing the energy yield assessment is the site-specific insolation. Several aspects need to be considered: reliability of the database, interannual variability, long term trends.Site adaptation techniques combine short-term measured data and long-term satellite estimates. Short periods of measured data but with site-specific seasonal and diurnal characteristics are combined with satellite-derived data having a long period of record with not necessarily site-specific characteristics. Upon completion of the measurement campaign, which is typically around one-year, different methodologies can be applied between the measured data at the target site, spanning a relatively short period, and the satellite data, spanning a much longer period. The complete record of satellite data is then used in this relationship to predict the long-term solar resource at the target site. Assuming a strong correlation, the strengths of both data sets are captured and the uncertainty in the long-term estimate can be reduced. In Müller et al [1] an analysis on long-term trends for measured in-plane irradiance, Performance Ratio and energy yield for 44 rooftop installations in Germany was performed showing an average increase of in-plane irradiance of 1.1 %/year or about 11 %/decade over the period 2008 to 2018 for these systems. The increase in irradiance was especially higher than the observed Performance Loss Rate so that the energy yields of the systems analysed increased over the years with an average trend of 0.3 %/year. The typical output of Yield Assessments should report the contribution to each derating factor, starting from the Global Horizontal Irradiation to the energy injected in the grid. The starting point of PR = 100 is considered after applying the horizon shading as this become the annual insolation seen by the PV modules. The following table shows a best practice in providing an overview of gains/losses along each modelling step and the related uncertainty. The uncertainty related to each modelling step can be provided already referred to the irradiation/yield value or to the parameter that is modelled. The value in the table for the specific yield (including its uncertainty) is to be understood as an average value over the entire operating period. The possible deviations between the yields for individual recorded years and the specific yield calculated can be assessed by including interannual variability. For example, for temperature-dependent losses, the value of uncertainty could be referred to the temperature variability of the profile used in the assessment or to the temperature model used in the assessment. The ambient temperature variability and the various temperature models will lead to a different contribution in terms of yield loss and in terms of uncertainty.An emerging challenge in YAs is also due to the deployment of novel technologies (e.g. bifacial PV modules) with a contribution in terms of uncertainty that needs to be properly assessed.Building upon the knowledge available in the literature and the previous IEA PVPS Task 13 report [2], in this report we have moved forward from the uncertainty framework in yield assessment to two real implementations of it and the impact that uncertainties can have on lifetime yield predictions, on the LCOE and on the cash-flow.One of the most relevant question that we have tried to answer is also the following: How reliable are YA’s?This is an apparently simple question; however, the answer is not equally simple. Typically, investors require one YA. In some cases, more YAs might be requested if results are unclear. The various YAs can be averaged to assign a purchase value to a given project. In any case the question remains unanswered: why different assessors obtain different answers? Is one YA more reliable than others?
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| 17. |
- Stridh, Bengt, Universitetslektor, 1957-, et al.
(författare)
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Utvärdering av egenanvändning av solel i Sverige
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I Sverige har saknats lättillgänglig statistik för egenanvändningen av solel för existerande solcellsanläggningar. Projektets syfte var att råda bot på denna kunskapsbrist. Med egenanvänd solel menas el som produceras med solceller och som används av solelproducenten i syfte att minska mängden köpt el. Egenanvändningens storlek påverkar solcellsägarens ekonomi, elnätinvesteringar som nätförstärkningar, kostnad för stödsystem i form av skattereduktion för överskottsel som matas in till nätet och kännedomen om storleken av den svenska solelproduktionen.Resultatet tyder på att egenanvändningen av solel i Sverige under 2018 var 36% för anläggningar upp till 20 kW installerad effekt och 41% för anläggningar mellan 20 och 1000 kW. Via tio olika kanaler har uppgifter för att beräkna egenanvändning av solel insamlats från närmare tusen solcellsanläggningar. Från dessa uppgifter har det tagits fram den mest noggranna uppskattning hittills av andelen solelproduktion som är egenanvänd av solelproducenten. Det finns stor spridning i egenanvändning mellan 0% och 100% och rapporten exemplifierar orsaker till dessa variationer.En Excelmall har tagits fram för beräkning av egenanvändning av solel för en planerad solcellsanläggning, med hjälp av timdata för elanvändning och förväntad solelproduktion. Den beräknade egenanvändning kan användas av solcellsförsäljare och potentiella solcellsägare som nödvändigt underlag för beräkning av lönsamheten för en solcellsinvestering.Sveriges totala solelproduktion under 2019 beräknades till 0,4 TWh genom att utgå från av Svenska Kraftnäts insamlade data för inmatad el till nätet och med hänsyn tagen till den solel som är egenanvänd, som inte ingår i de data som samlas in av Svenska Kraftnät. Denna metod för att beräkna Sveriges totala solelproduktion jämfördes med resultaten från två andra metoder.Olika metoder att påverka egenanvändning av solel i byggnad, liksom vad som påverkar lönsamheten för en solcellsinvestering beskrivs. En internationell översyn av styrmedel och metoder att öka egenanvändning av solel i byggnader i ett urval av Europeiska länder gjordes som en litteraturstudie. Det för närvarande främsta sättet att ytterligare stimulera till mer installerade solceller i Sverige vore att ta bort gränsen på 255 kW för full energiskatt på egenanvänd el, vilken gör att stora tak inte utnyttjas fullt ut idag.Slutligen ges förslag på framtida arbeten för att förbättra noggrannheten av beräknad egenanvändning och Sveriges totala solelproduktion.
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| 18. |
- Yang, Ying, et al.
(författare)
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Potential analysis of roof-mounted solar photovoltaics in Sweden
- 2020
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Ingår i: Applied Energy. - : ELSEVIER SCI LTD. - 0306-2619 .- 1872-9118. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- Solar photovoltaic energy, driven mostly by the residential and commercial market segments, has been growing a lot in recent years in Sweden. In response to the commitment towards sustainability goals, this paper explores the potential of roof-mounted solar photovoltaic projects. This paper focuses on: roof area estimation, potential installed capacity, and potential electricity generation, at the single municipal scale and at the national scale. The following categories of different building types have been investigated: residential buildings, industrial buildings, buildings of social function, buildings of business function, buildings of economic/agricultural function, buildings of complementary function, and buildings of other unknown functions. The analysis starts from Vasteras, a typical Swedish municipality and ranking seventh among the largest cities in Sweden. An estimate of 5.74 km(2) available roof area potential is calculated, by considering factors such as building purposes, roof orientations, shadows and obstacles. The total potential installed capacity is calculated, assuming the installation of commercial photovoltaic modules, and design parameters for flat roofs such as inter-row distances and tilt angles. With the inputs of meteorological parameters and geographical information, the potential yearly electricity generation is calculated. The results reveal 727, 848, and 956 MWp potential installed capacity and 626, 720, and 801 GWh annual electricity production for Vasteras on pitched roofs and flat roofs with three scenarios, respectively. The extrapolation of the methodology to the entire of Sweden yields a total of 504 km(2) usable roof area and 65, 75, and 84 GWp installed capacity. Finally, we reveal a new understanding of usable roof area distribution and of potential installed capacity of roof-mounted solar photovoltaic systems, which can largely help evaluate subsidy scale and solar energy policy formulation in Sweden.
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| 19. |
- Zainali, Sebastian, et al.
(författare)
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Computational fluid dynamics modelling of microclimate for a vertical agrivoltaic system
- 2023
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Ingår i: Energy Nexus. - : Elsevier BV. - 2772-4271. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The increasing worldwide population is leading to a continuous increase in energy and food demand. These increasing demands have led to fierce land-use conflicts as we need agricultural land for food production while striving towards renewable energy systems such as large-scale solar photovoltaic (PV) systems, which also require in most of the cases agricultural flat land for implementation. It is therefore essential to identify the interrelationships between the food, and energy sectors and develop sustainable solutions to achieve global goals such as food and energy security. A technology that has shown promising potential in supporting food and energy security, as well as supporting water security, is agrivoltaic (AV) systems. This technology combines conventional farm activities with PV systems on the same land. Understanding the microclimatic conditions in an AV system is essential for an accurate assessment of crop yield potential as well as for the energy performance of the PV systems. Nevertheless, the complex mechanisms governing the microclimatic conditions under agrivoltaic systems represent an underdeveloped research area. In this study, a computational fluid dynamics (CFD) model for a vertical AV system is developed and validated. The CFD model showed PV module temperature estimation errors in the order of 0–2 °C and ground temperature errors in the order of 0–1 °C. The shading caused by the vertical PV system resulted in a reduction of solar irradiance by 38%. CFD modelling can be seen as a robust approach to analysing microclimatic parameters and assessing AV system performance.
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| 20. |
- Zainali, Sebastian, et al.
(författare)
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Direct and diffuse shading factors modelling for the most representative agrivoltaic system layouts
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Agrivoltaic systems are becoming more popular as a critical technology for attaining several sustainable development goals such as affordable and clean energy, zero hunger, clean water and sanitation, and climate action. However, understanding the shading effects on crops is fundamental to choosing an optimal agrivoltaic system as a wrong choice could lead to severe crop reductions. In this study, fixed vertical, one-axis tracking, and two-axis tracking photovoltaic arrays for agrivoltaic applications are developed to analyse the shading conditions on the ground used for crop production. The models have shown remarkably similar accuracy compared to commercial software such as PVsyst® and SketchUp®. The developed models will help reduce the crop yield uncertainty under agrivoltaic systems by providing accurate photosynthetically active radiation distribution at the crop level. The distribution was further analysed using a light homogeneity index and calculating the yearly photosynthetically active radiation reduction. The homogeneity and photosynthetically active radiation reduction varied significantly depending on the agrivoltaic system design, from 91% to 95% and 11% to 34%, respectively. To identify the most suitable agrivoltaic system layout dependent on crop and geographical location, it is of fundamental importance to study the effect of shadings with distribution analysis.
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| 21. |
- Zainali, Sebastian, et al.
(författare)
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Direct and diffuse shading factors modelling for the most representative agrivoltaic system layouts
- 2023
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 339
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Tidskriftsartikel (refereegranskat)abstract
- Agrivoltaic systems are becoming increasingly popular as a crucial technology for attaining multiple sustainable development goals, such as affordable and clean energy, zero hunger, clean water and sanitation, and climate action. However, a comprehensive understanding of the shading effects on crops is essential for choosing an optimal agrivoltaic system, as an incorrect choice can result in significant crop yield reductions. In this study, fixed vertical, one-axis tracking, and two-axis tracking photovoltaic arrays were developed for agrivoltaic applications to analyse the shading conditions on the ground used for crop production. The models demonstrated remarkable accuracy in comparison to commercial software such as PVsyst® and SketchUp®. These models will help to reduce crop yield uncertainty under agrivoltaic systems by providing accurate photosynthetically active radiation distribution at the crop level. The photosynthetically active radiation distribution was further analysed using a light homogeneity index, and the results showed that homogeneity and photosynthetically active radiation reduction varied significantly depending on the agrivoltaic system design, ranging from 86% to 95%, and 11% to 22%, respectively. Studying the effect of shading with distribution analysis is crucial for identifying the most suitable agrivoltaic system layout for specific crops and geographical locations.
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| 22. |
- Zainali, Sebastian, et al.
(författare)
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LCOE distribution of PV for single-family dwellings in Sweden
- 2023
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Ingår i: Energy Reports. - 2352-4847. ; 10, s. 1951-1967
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, the installations of solar photovoltaic systems are growing rapidly, and especially the market segment of small-scale distributed systems is experiencing positive growth. The current installation volumes exceed the expectations of the Swedish authorities. This study presents an up-to-date assessment of the levelized cost of electricity to be used for both agencies in their long-term scenario work of PV development and for private investors for estimating the upfront and future costs and risks associated with photovoltaic systems. The analysis is based on the turnkey system cost of 6,098 single-family dwelling photovoltaic systems commissioned in Sweden between the 1st of January 2019 and 1st of July 2020. The statistics of system investments costs are complemented by literature studies and by interviews of relevant stakeholders for the other input parameters needed to calculate the Levelized Cost of Electricity (LCOE). A Monte Carlo analysis was applied on all the input parameters provides relevant insight into the range of LCOE values. The unsubsidized levelized cost of electricity for most systems ranged from 0.85 SEK/kWh (25th percentile) to 1.15 SEK/kWh (75th percentile), with a mean at 1.02 SEK/kWh at reasonable real discount rate of 2%, but that extreme values can reach 0.30 SEK/kWh at a 0% discount rate and 5.70 SEK/kWh at a 5% discount rate. Taking into account the current (2023) Swedish tax reduction for investment in green technologies that amounts to an effective deduction of 19.4% of the total system investment costs lowers the LCOE to mean at 0.82 SEK/kWh at real discount rate of 2%. The LCOE for single-family dwelling photovoltaic systems are generally lower than the assumed LCOE in long-term scenario studies of the Swedish electricity system. This finding helps to explain to the authorities the unexpected fast deployment of distributed photovoltaic systems in Sweden.
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