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  • 1.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Cioccolanti, L.
    Centro di Ricerca per l'Energia, l'Ambiente e il Territorio, Università Telematica eCampus, Novedrate (CO), 22060, Italy.
    François, B.
    Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01003, United States.
    Jurasz, Jakob
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Faculty of Management, AGH University, Kraków, 30-059, Poland; Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Wroclaw, 50-370, Poland.
    Zhang, Y.
    Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, 10044, Sweden.
    Varini, M.
    Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, 10044, Sweden.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li-ion batteries for peak shaving, price arbitrage, and photovoltaic self-consumption in commercial buildings: A Monte Carlo Analysis2021In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 234, article id 113889Article in journal (Refereed)
    Abstract [en]

    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 self-consumption. 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.

  • 2.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Cioccolanti, Luca
    François, B.
    Jurasz, J.
    Zhang, Yang
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A Multi-Country Economic Analysis Of Lithium-Ion Batteries For Peak Shaving And Price Arbitrage In Commercial Buildings2018Conference paper (Refereed)
  • 3.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Holmberg, Aksel
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Pettersson, Oscar
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Klintenberg, Patrik
    Hangula, A.
    Namibia Energy Institute, Namibia University of Science and Technology, Windhoek, Namibia.
    Araoz, F. B.
    School of Chemical Science & Engineering, KTH Royal Institute of Technology, Teknikringen 42, Stockholm, Sweden.
    Zhang, Y.
    School of Chemical Science & Engineering, KTH Royal Institute of Technology, Teknikringen 42, Stockholm, Sweden.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB AB, Corporate Research, Västerås, Sweden.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. School of Chemical Science & Engineering, KTH Royal Institute of Technology, Teknikringen 42, Stockholm, Sweden.
    An open-source optimization tool for solar home systems: A case study in Namibia2016In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 130, no 15, p. 106-118Article in journal (Refereed)
    Abstract [en]

    Solar home systems (SHSs) represent a viable technical solution for providing electricity to households and improving standard of living conditions in areas not reached by the national grid or local grids. For this reason, several rural electrification programmes in developing countries, including Namibia, have been relying on SHSs to electrify rural off-grid communities. However, the limited technical know-how of service providers, often resulting in over- or under-sized SHSs, is an issue that has to be solved to avoid dissatisfaction of SHSs’ users. The solution presented here is to develop an open-source software that service providers can use to optimally design SHSs components based on the specific electricity requirements of the end-user. The aim of this study is to develop and validate an optimization model written in MS Excel-VBA which calculates the optimal SHSs components capacities guaranteeing the minimum costs and the maximum system reliability. The results obtained with the developed tool showed good agreement with a commercial software and a computational code used in research activities. When applying the developed optimization tool to existing systems, the results identified that several components were incorrectly sized. The tool has thus the potentials of improving future SHSs installations, contributing to increasing satisfaction of end-users.

  • 4.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Landelius, T.
    Swedish Meteorological and Hydrological Institute, Norrköping, Sweden.
    Andersson, S.
    Swedish Meteorological and Hydrological Institute, Norrköping, Sweden.
    Lundström, Lukas
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Nordlander, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    He, T.
    Wuhan University, Wuhan, China.
    Zhang, J.
    Uppsala University, Uppsala, Sweden.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    A gridded optimization model for photovoltaic applications2020In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 202, p. 465-484Article in journal (Refereed)
    Abstract [en]

    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 STRÅNG 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. STRÅNG 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.

  • 5.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Li, Hailong
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zaccaria, Valentina
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zhang, Yang
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Flexibility Services Provided by Building Thermal Inertia2018Conference paper (Refereed)
  • 6.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Amaducci, S.
    Università Cattolica del Sacro Cuore, Department of Sustainable Crop Production, Via Emilia Parmense 84, Piacenza, Italy.
    Colauzzi, M.
    Università Cattolica del Sacro Cuore, Department of Sustainable Crop Production, Via Emilia Parmense 84, Piacenza, Italy.
    Optimisation of vertically mounted agrivoltaic systems2021In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 325, article id 129091Article in journal (Refereed)
    Abstract [en]

    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.

  • 7.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Hörndahl, T.
    Swedish University of Agricultural Sciences, Department of Biosystems and Technology, Alnarp, Sweden.
    Svensson, S. -E
    Swedish University of Agricultural Sciences, Department of Biosystems and Technology, Alnarp, Sweden.
    Zainali, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ma Lu, Silvia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zidane, Tekai Eddine Khalil
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    De Luca, P.
    Barcelona Supercomputing Center, Barcelona, Spain.
    Amaducci, S.
    Università Cattolica del Sacro Cuore, Department of Sustainable Crop Production, Piacenza, Italy.
    Colauzzi, M.
    Università Cattolica del Sacro Cuore, Department of Sustainable Crop Production, Piacenza, Italy.
    Experimental results, integrated model validation, and economic aspects of agrivoltaic systems at northern latitudes2024In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 437, article id 140235Article in journal (Refereed)
    Abstract [en]

    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.

  • 8.
    Campana, Pietro Elia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zainali, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ma Lu, Silvia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Andersson, Ulf
    Kärrbo Prästgård AB, Sweden.
    Nordström, Josefin
    Solkompaniet Sverige AB, Sweden.
    Bergdahl, Pontus
    Solkompaniet Sverige AB, Sweden.
    Hörndahl, Torsten
    Swedish University of Agricultural Sciences, SLU, Sweden.
    Svensson, Sven-Erik
    Swedish University of Agricultural Sciences, SLU, Sweden.
    Evaluation of the first agrivoltaic system in Sweden2023Report (Other academic)
    Abstract [en]

    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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  • 9.
    Elkadeem, M. R.
    et al.
    Interdisciplinary Research Center for Renewable Energy and Power Systems (IRC-REPS), King Fahd University of Petroleum & Minerals (KFUPM), Dhahran, Saudi Arabia.
    Zainali, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ma Lu, Silvia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Younes, A.
    Geography and GIS Department, Faculty of Arts, Kafrelsheikh University, Kafrelsheikh, Egypt.
    Abido, M. A.
    SDAIA-KFUPM Joint Research Center for Artificial Intelligence, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia.
    Amaducci, S.
    Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Piacenza, Italy.
    Croci, M.
    Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, Piacenza, Italy.
    Zhang, J.
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden.
    Landelius, T.
    Swedish Meteorological and Hydrological Institute, Norrköping, Sweden.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Agrivoltaic systems potentials in Sweden: A geospatial-assisted multi-criteria analysis2024In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 356, article id 122108Article in journal (Refereed)
    Abstract [en]

    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. 

  • 10.
    Johansson, F.
    et al.
    Mälardalen University.
    Gustafsson, Bengt Erik
    Mälardalen University, School of Innovation, Design and Engineering, Innovation and Product Realisation.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    3D-thermal modelling of a bifacial agrivoltaic system: a photovoltaic module perspective2022In: Energy Nexus, ISSN 2772-4271, Vol. 5, article id 100052Article in journal (Refereed)
    Abstract [en]

    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 conditions

    The 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.

  • 11.
    Larsson, David
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Karlsson, Björn
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Solar Electricity in Swedish District Heating Areas: Effective Energy Measures in Apartment Buildings to Increase the Share of Renewable Energy in Europe2014In: Proceedings from the 14th International Symposium on District Heating and Cooling / [ed] Anna Land, Stockholm: Svensk Fjärrvärme , 2014Conference paper (Refereed)
    Abstract [en]

    To overcome the climate challenge is one of the greatest tasks of our time. In EU, renovating the existing building stock has been found an effective measure. In Swedish buildings with district heating, lowering heat demand could be questioned, because the energy used is mainly renewable bio energy or waste heat from industries. In addition many district heating systems cogenerate electricity, which could reduce the overall European greenhouse gas emissions.

    The aim of this article is to find effective measures for Swedish apartment buildings, in order to increase the share of renewable energy in European energy consumption. As a basis we use a previous study of energy saving potentials in apartment buildings. Added to this we study the impact of heat savings in 30 of Sweden’s largest district heating systems.

    The results show that on average heat reductions will lead to a decreased share of renewable energy, while electricity reductions will lead to an increased share of renewables. Of the investigated measures, using photovoltaics for local solar electricity generation has the largest potential.

    Our conclusion is that using the potential of solar electricity production should be considered in national energy policy and future building requirements. Heat reduction, on the other hand, could have lower priority in district heating areas, at least for existing buildings.

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  • 12.
    Lu, Silvia Ma
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yang, D.
    School of Electrical Engineering and Automation, Harbin Institute of Technology 2 , Harbin, Heilongjiang, China.
    Anderson, M. C.
    USDA ARS, Hydrology and Remote Sensing Laboratory 3 , Beltsville, Maryland 20705, USA.
    Zainali, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Photosynthetically active radiation separation model for high-latitude regions in agrivoltaic systems modeling2024In: Journal of Renewable and Sustainable Energy, E-ISSN 1941-7012, Vol. 16, no 1, article id 013503Article in journal (Refereed)
    Abstract [en]

    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.

  • 13.
    Ma Lu, Silvia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zainali, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Amaducci, S.
    Univ Cattolica Sacro Cuore, Dept Sustainable Crop Prod, Via Emilia Parmense 84, I-29122 Piacenza, Italy..
    Colauzzi, M.
    Univ Cattolica Sacro Cuore, Dept Sustainable Crop Prod, Via Emilia Parmense 84, I-29122 Piacenza, Italy..
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Photosynthetically active radiation decomposition models for agrivoltaic systems applications2022In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 244, p. 536-549Article in journal (Refereed)
    Abstract [en]

    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.

  • 14.
    Ma Lu, Silvia
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zainali, Sebastian
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sundström, Elin
    Mälardalen University.
    Nygren, Anton
    Mälardalen University.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Validation of Vertical Bifacial Agrivoltaic and Other Systems Modelling: Effect of Dynamic Albedo on Irradiance and Power Output Estimations2023Conference paper (Refereed)
    Abstract [en]

    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. 

  • 15.
    Molin, Elin
    et al.
    Dalarna Univ, Energy Technol, SE-79188 Falun, Sweden.;PPAM Solkraft AB, Corp Res, SE-59072 Ljungsbro, Sweden..
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Molin, Andreas
    PPAM Solkraft AB, Corp Res, SE-59072 Ljungsbro, Sweden.;Linkoping Univ, Dept Management & Engn, Div Energy Syst, SE-58183 Linkoping, Sweden..
    Waeckelgard, Ewa
    Dalarna Univ, Energy Technol, SE-79188 Falun, Sweden..
    Experimental Yield Study of Bifacial PV Modules in Nordic Conditions2018In: IEEE Journal of Photovoltaics, ISSN 2156-3381, E-ISSN 2156-3403, Vol. 8, no 6, p. 1457-1463Article in journal (Refereed)
    Abstract [en]

    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 Linkoping (58 degrees N) and were studied fromDecember 2016 to November 2017. Site 1 has monofacial and bifacial modules with a 40 degrees tilt facing south, which is optimal for annual energy yield for monofacial modules at this location. Site 2 has monofacial 40 degrees tilt south-facing modules and bifacial vertical east-west orientated modules. The annual bifacial energy gain (BGE) was5% at site 1 and1% 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.

  • 16.
    Philippe, Macé
    et al.
    Becquerel Institute, Belgium.
    Larsson, David
    Solkompaniet, Sweden.
    Benson, Jessica
    RISE, Sweden.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Inventory on Existing Business Models, Opportunities and Issues for BIPV: IEA PVPS Task 15 Subtask B – Transition towards sound BIPV business models2018Report (Other academic)
    Abstract [en]

    Building integrated photovoltaics (BIPV) can have a vastly different business model than other PV installations; applied on buildings or ground mounted. Business models for ordinary PV installations generally focus only on revenues from the electricity generated, whereas BIPV has the potential to also reduce costs through the replacement of other building materials.

    This report includes examples of various BIPV installations ranging from simple in-roof installations to innovative facade designs. The timing of introducing BIPV in the design process affects the complexity of the façade. The façade examples cover the use of standard modules to custom-made modules adapted to the design. The BIPV roof examples cover both small, simple in-roof installations and a full roof BIPV solution. Results from the studied cases, show that only one of the involved companies have a BIPV-specific business model in place.

    A basic BIPV-specific business model could be based solely on cost savings from replacing other building materials and revenues from electricity generation. This is viable if the BIPV installation has sufficiently low cost, or if the value of the replaced materials and electricity generated is sufficiently high. A BIPV specific business model is found in the case with a full BIPV roof, an installation that arose from the need for a roof renovation. The other examples are also based on material savings and electricity revenues but many were made with publicly funded incentives like investment subsidies.

    The purpose of the case study is to identify the main drives for choosing BIPV in each example. These drives and values can be used as a basis in the development of new business models. For example, there is a green value, i.e. value of being environmentally friendly and sustainable, attached to PV, which could be significantly higher for a good looking, architecturally integrated BIPV installation than for the average PV system. For example, the green identity attracts high paying customers as tenants in two of the cases, which allows for higher rental fees. Future work is needed to explore ways to fully capture and monetize the green value of a building with BIPV.

    Another business model, shown in one example, could be to build and sell the building at a premium. So far, there is no clear evaluation of the price premium of a building with BIPV. On the other hand, compared to the total cost of a new building, the cost of a BIPV installation is seemingly moderate. In two of the examples with large BIPV facades, the added cost was only 1-2 % of the building cost. A leasing arrangement with the utilty is also described in one example.

    In the future, it is likely that BIPV must cope without investment subsidies and that electricity revenues will be high from self-consumption, but low from excess production. Highlighted in the analysis of regulatory environment is the need for collective self-consumption to be allowed. BIPV can also benefit from regulatory measures imposing a reduced purchased energy demand of new or retrofitted buildings.

    Download full text (pdf)
    Inventory on Existing Business Models, Opportunities and Issues for BIPV
  • 17.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sveriges första MW-solcellspark och dess forskningssystem: En systembeskrivning2016Report (Other academic)
    Abstract [en]

    In 2013 began the construction of a 1 MW solar park immediately north of the E18 at Onsmyran, 10 km east of Västerås. It was inaugurated on February 5, 2014. It was at that time the largest photovoltaic plant in Sweden and the second largest in the Nordic region.

    The project's aim was to increase understanding and provide an opportunity to influence how future PV installations should be carried out in Sweden in as cost effective manner as possible and thereby become an attendant for increased solar electricity generation in Sweden.

    In the project ten smaller research systems were evaluated in detail. The purpose of this report is to provide a description of the MW solar park and provide a detailed description of the ten research systems with 3.0 to 8.4 kW power as assessed in detail in the project.

    The different research systems were

    • 2-axis tracking freestanding.

    • 1 axis tracking freestanding, tilted axis 30°.

    • Fixed mounting freestanding, 19° tilt.

    • Fixed mounting freestanding, 41° tilt.

    • Fixed mounting on a roof, 19° tilt.

     

    All of the above PV systems were available with and without power optimizer on each module.

    Installation and operating experiences of especially the research systems are described in this report, since it may be useful information for future PV installations in Sweden. Problems with data logging is a more common source of error than failure of solar modules. The conclusions give reflections on things to consider when setting up a logging system.

    In this report no measurement results or conclusions based on the measurement results were made. This will be reported in a separate report.

  • 18.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Abrahamsson, Roger
    Tekniska verken Linköping Elnät AB.
    Etherden, Nicholas
    Vattenfall AB.
    Rydqvist, Mari
    HESAB.
    Utvärdering av egenanvändning av solel i Sverige2020Report (Other academic)
    Abstract [sv]

    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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    Utvärdering av egenanvändning av solel i Sverige - Slutrapport
  • 19.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Sandra, Andersson
    SMHI.
    Thomas, Carlund
    SMHI.
    Tomas, Landelius
    SMHI.
    Nordlander, Eva
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Vadiee, Amir
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Förbättrad beräkning av solelproduktion i Sverige2020Report (Other academic)
    Abstract [en]

    Northern location with lower solar radiation than southern Europe and relatively low electricity prices means that accurate predictions of energy yield from photovoltaic (PV) systems are of great importance when making investment calculations in Sweden. More accurate calculations of expected PV yield result in less economic uncertainty, which results in a more resource-efficient development. The choice of meteorological data and calculation method for PV yield is therefore of great importance

    One question is which simulation program for PV yield is best to use in Sweden. OptiCE, Polysun, PVsyst and PV*SOL using the programs meteorological databases are relatively equivalent in this work for Stockholm, Norrköping and Visby. The agreement is relatively good with the measured values ​​for PV yield in 2019, with differences of less than ±5%. But they all give 13%-15% too high values ​​for Kiruna. PVGIS with database ERA5 gives slightly larger deviations for Stockholm, Norrköping and Visby than the above-mentioned programs but gives a value close to the measured in 2019 in Kiruna. SAM and PVGIS with the databases SARAH or COSMO give larger deviations than the above-mentioned programs. As SARAH in a comparative study had best accuracy, it is conceivable that PVGIS calculations could be improved by choosing SARAH in combination with a lower value than the default setting of 14% for system losses.

    The greatest uncertainty in estimating solar cell systems electricity production comes from solar radiation data. By improving solar radiation data and making it publicly available, investors are helped to make decisions with reduced uncertainty. There is a need for an industry standard for solar radiation data in Sweden. A further development of the STRÅNG model for solar radiation data is desirable. A standard procedure for calculating the effect of shading would also be valuable, as shading can have a major impact on PV yield.

    Data for solar radiation, wind, temperature and albedo from the climate scenario for two periods (2030-2065 and 2066-2095) were used to estimate how solar production may be affected in a future climate. The results indicate that PV yield is declining somewhat, but that the change is only statistically significant in the scenario that represents continued high carbon dioxide emissions and then only for northern Sweden during the recent period. Across the country, the change for this period is estimated to be between -9% (10th percentile) and -2% (90th percentile) with an average value of about -6%.

    The maps for Sweden for optimized slopes, solar radiation and solar production produced with the developed model OptiCE are a tool for better understanding, designing and improving installations of PV systems in Sweden.

    Among the models examined for the decomposition of global horizontal solar radiation into diffuse and direct radiation to produce own solar radiation data for use in simulation programs, the conclusion is that for hourly values ​​Engerer2 or Paulescu and Blaga are suitable choices. Of the models studied for 1-minute values, Yang2 shows the best performance.

    Download full text (pdf)
    Förbättrad beräkning av solelproduktion i Sverige - Slutrapport
  • 20.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Larsson, David
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Investeringskalkyl för solceller2016Report (Other academic)
  • 21.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Macé, Philippe
    Becquerel Institute, Belgium.
    Frieden, Dorian
    Joanneum Research, Austria.
    Woess-Gallasch, Susanne
    Joanneum Research, Austria.
    Frederiksen, Kenn
    Kenergy, Denmark.
    Larsson, David
    Solkompaniet, Sweden.
    van Oorschot, John
    Zuyd University, Netherlands.
    Benson, Jessica
    RISE, Sweden.
    Román, Eduardo
    Tecnalia, Spain.
    Burgun, Françoise
    CEA, France.
    Development of BIPV Business Cases: Guide for stakeholders2020Report (Other academic)
    Abstract [en]

    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. 

  • 22.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Moser, David
    Institute for Renewable Energy, Eurac Research, Bolzano, Italy.
    Lindig, Sascha
    Institute for Renewable Energy, Eurac Research, Bolzano, Italy.
    Richter, Mauricio
    3E, Brussels, Belgium.
    Ascencio-Vásquez, Julián
    3E, Brussels, Belgium.
    Horvath, Imre
    IMEC, Leuven, Belgium.
    Müller, Björn
    Fraunhofer ISE, Freiburg, Germany.
    Green, Mike
    Green Power Engineering, Israel.
    Vedde, Jan
    European Energy, Denmark.
    Herz, Magnus
    TUV Rheinland, Cologne, Germany.
    Herteleer, Bert
    KU Leuven, Gent, Belgium.
    Weiss, Karl-Anders
    Fraunhofer ISE, Freiburg, Germany.
    Uncertainties in Yield Assessments and PV LCOE: Report IEA-PVPS T13-18:2020 November 20202020Report (Other academic)
    Abstract [en]

    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? 

  • 23.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB Corporate Research, Sweden.
    Rosenlind, Johanna
    Mälarenergi, Sweden.
    Bagge, Patrik
    Mälarenergi, Sweden.
    Sahoo, Smruti
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Zetterström, Patrik
    Uppsala University, Sweden.
    Power quality experiences from Sweden's first MW photovoltaics park and impact on LV planning2016In: IEEE ISGT 2016: Innovative Smart Grid Technologies, 2016Conference paper (Refereed)
    Abstract [en]

    The first 1 MW PV park in Sweden was installed in 2014. A concern from the grid owner perspective is how the growing number of PV installations will influence the power quality in their grids. The power quality impact from the 1 MW park was demonstrated to fall within the regulating limitations in EIFS 2013:1 for the following aspects: voltage changes, voltage harmonics, interharmonics, and voltage unbalance. However, the slow voltage variations were exceeding the Swedish industry recommendations (AMP) governing a single production source. This deviation occurred during 0.74% of the studied two-month period. To meet AMP recommendations it would have been necessary to install a separate cable intended only for the solar park itself and connected closer to the substation. Perhaps a more appropriate alternative would have been to connect the solar park on the closest 20 kV grid.

  • 24.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yard, Stefan
    Lunds Universitet.
    Larsson, David
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Karlsson, Björn
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Production cost of PV electricity in Sweden2013In: EU PVSEC Proceedings, 2013, p. 4718-4722, article id 6CV.5.13Conference paper (Other academic)
    Abstract [en]

    The photovoltaic (PV) market in Sweden is small in comparison to most of the other PV markets in the European countries. However, the market is growing and about 8 MW was installed during 2012 that is 1/3 of the totally installed power. It is expected that the market will continue to grow during 2013.The PV levelized cost of electricity (LCOE) in Sweden was studied for grid connected PV systems to understand how competitive PV is on the Swedish market. It is concluded that PV production cost is still too high to be competitive in utility scale on the Nord Pool spot market without subsidies. However, for residential or commercial systems the production cost for PV electricity is today in some cases in the same order of magnitude as, or lower than, the running cost for bought electricity even without investment subsidy or electricity certificates, with the assumed parameters for estimation of LCOE. With investment subsidy the calculation improves substantially resulting in a LCOE lower than the running cost for bought electricity. To a much smaller extent an improvement of LCOE is also seen with electricity certificates.

  • 25.
    Stridh, Bengt
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB Corp Res, SE-72178 Vasteras, Sweden.
    Yard, Stefan
    Lund Univ, Sweden..
    Larsson, David
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Solkompaniet, SE-72178 Vasteras, Sweden..
    Karlsson, Björn
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Profitability of PV electricity in Sweden2014In: 2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), IEEE , 2014, p. 1492-1497Conference paper (Refereed)
    Abstract [en]

    The Swedish PV market is still limited compared to many other countries in Europe. However, the growth is strong. 19 MW was installed in 2013 showing that the market more than doubled during 2013 in comparison to 2012. Hence there is of interest to more in detail study the profitability of PV electricity in Sweden for grid connected PV systems, to understand how competitive PV is on the Swedish market. LCOE and payback period are presented for a PV system that is installed to replace retail electricity with PV electricity. Both the cases of private residential systems and of non-private systems are considered.

  • 26.
    Vedde, Jan
    et al.
    SiCon.
    Richter, Mauricio
    Tjendgdrawira, Caroline
    KU Leuven.
    Herteleer, Bert
    KU Leuven och CAT Projects.
    Herz, Magnus
    TÜV Rheinland Energie und Umwelt GmbH.
    Jahn, Ulrike
    TÜV Rheinland Energie und Umwelt GmbH.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. ABB Corporate Research.
    Frearson, Lyndon
    CAT Projects.
    Green, Mike
    M.G. Lightning ltd.
    Technical Parameters Used in PV Financial Models: Review and Analysis2016In: 32nd European Photovoltaic Solar Energy Conference and Exhibition, 2016, p. 2897-2902, article id 7DO.14.4Conference paper (Refereed)
    Abstract [en]

    When photovoltaic (PV) projects are developed and constructed for investment purposes, financing from professional investors and banks are required, and financial models are developed that describe the expected cash-flow generated by the PV plant over the economic lifetime of the project. The calculation is based on models that require both technical and financial inputs. In this paper we will review and analyse the technical assumptions in these models and discuss how the technical assumptions are typically used and to what extent the uncertainty related to the input parameters are appropriately addressed. Finally, a calculation and visualisation method is presented that highlights the nature and effect of this uncertainty.

  • 27.
    Yang, Ying
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. Department of Chemical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Potential analysis of roof-mounted solar photovoltaics in Sweden2020In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 279, article id 115786Article in journal (Refereed)
    Abstract [en]

    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 Västerås, a typical Swedish municipality and ranking seventh among the largest cities in Sweden. An estimate of 5.74 km2 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 Västerås 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 km2 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. 

  • 28.
    Zainali, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lindahl, Johan
    Chalmers University of Technology, Department of Technology Management and Economics, SE-412 96, Göteborg, Sweden.
    Lindén, Johan
    Mälardalen University, School of Business, Society and Engineering, Industrial Economics and Organisation.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    LCOE distribution of PV for single-family dwellings in Sweden2023In: Energy Reports, E-ISSN 2352-4847, Vol. 10, p. 1951-1967Article in journal (Refereed)
    Abstract [en]

    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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  • 29.
    Zainali, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ma Lu, Silvia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Amaducci, S.
    Università Cattolica del Sacro Cuore, Dept. of Sustainable Crop Production, Piacenza, Italy.
    Colauzzi, M.
    Università Cattolica del Sacro Cuore, Dept. of Sustainable Crop Production, Piacenza, Italy.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Direct and diffuse shading factors modelling for the most representative agrivoltaic system layouts2023In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 339, article id 120981Article in journal (Refereed)
    Abstract [en]

    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.

  • 30.
    Zainali, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Ma Lu, Silvia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Amaducci, Stefano
    Università Cattolica del Sacro Cuore, Dept. of Sustainable Crop Production, Emilia Parmense 84, Piacenza, Italy.
    Colauzzi, Michele
    Università Cattolica del Sacro Cuore, Dept. of Sustainable Crop Production, Emilia Parmense 84, Piacenza, Italy.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Direct and diffuse shading factors modelling for the most representative agrivoltaic system layoutsManuscript (preprint) (Other academic)
    Abstract [en]

    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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  • 31.
    Zainali, Sebastian
    et al.
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Qadir, Omar
    Mälardalen University.
    Parlak, Sertac Cem
    Mälardalen University.
    Lu, Silvia Ma
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Avelin, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Computational fluid dynamics modelling of microclimate for a vertical agrivoltaic system2023In: Energy Nexus, ISSN 2772-4271, Vol. 9, article id 100173Article in journal (Refereed)
    Abstract [en]

    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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  • 32.
    Zhang, Y.
    et al.
    KTH-Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH-Royal Institute of Technology, Stockholm, Sweden.
    Yang, Ying
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Stridh, Bengt
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center.
    Lundblad, Anders
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. RISE Research Institutes of Sweden, Borås, Sweden.
    Yan, Jinyue
    Mälardalen University, School of Business, Society and Engineering, Future Energy Center. KTH-Royal Institute of Technology, Stockholm, Sweden.
    Energy flexibility from the consumer: Integrating local electricity and heat supplies in a building2018In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 223, p. 430-442Article in journal (Refereed)
    Abstract [en]

    The increasing penetration level of renewable energy requires more flexibility measures to be implemented in future energy systems. Integrating an energy consumer’s local energy supplies connects multiple energy networks (i.e., the electrical grid, the district heating network, and gas network) in a decentralized way. Such integration enhances the flexibility of energy systems. In this work, a Swedish office building is investigated as a case study. Different components, including heat pump, electrical heater, battery and hot water storage tank are integrated into the electricity and heat supply system of the building. Special focus is placed on the flexibility that the studied building can provide to the electrical grid (i.e., the building modulates the electricity consumption in response to the grid operator’s requirements). The flexibility is described by two metrics including the flexibility hours and the flexibility energy. Optimization of the component capacities and the operation profiles is carried out by using Mixed Integer Linear Programming (MILP). The results show that the system fully relies on electricity for the heat demand when not considering the flexibility requirements of the electrical grid. This suggests that district heating is economically unfavorable compared with using electricity for the heat demand in the studied case. However, when flexibility requirements are added, the system turns to the district heating network for part of the heat demand. The system provides great flexibility to the electrical grid through such integration. The flexibility hours can be over 5200 h in a year, and the flexibility energy reaches more than 15.7 MWh (36% of the yearly electricity consumption). The yearly operation cost of the system slightly increases from 62,273 to 65,178 SEK when the flexibility hours increase from 304 to 5209 h. The results revealed that flexibility can be provided from the district heating network to the electrical grid via the building.

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