Anne Gerd Imenes

• Paudyal, Basant Raj; Somasundaram, Sakthi Guhan; Louwen, Atse; Reinders, Angele H.M.E.; van Sark, Wilfried G.J.H.M. & Stellbogen, Dirk [Vis alle 8 forfattere av denne artikkelen] (2024). Analysis of spectral irradiance variation in northern Europe using average photon energy distributions. Renewable Energy. ISSN 0960-1481. 224, s. 1–21. doi: 10.1016/j.renene.2024.120057.
• Imenes, Anne Gerd (2022). PEARL PV Country Reports 2020 - Norway. I Farkas, Istvan; Atsu, Divine; Raghoebarsing, Amrita; Boddaert, Simon; Moser, David & Reinders, Angele (Red.), PEARL PV Country Reports 2020. University of Twente. ISSN 9789036553629. s. 187–199. doi: 10.3990/1.9789036553629.
• Høiaas, Ingeborg; Grujic, Katarina; Imenes, Anne Gerd; Burud, Ingunn; Olsen, Espen & Belbachir, Nabil (2022). Inspection and condition monitoring of large-scale photovoltaic power plants: A review of imaging technologies. Renewable and Sustainable Energy Reviews. ISSN 1364-0321. 161. doi: 10.1016/j.rser.2022.112353. Vis sammendrag

  The massive growth of PV farms, both in number and size, has motivated new approaches in inspection system design and monitoring. This paper presents a review of imaging technologies and methods for analysis and characterization of faults in photovoltaic (PV) modules. The paper provides a brief overview of PV system (PVS) reliability studies and monitoring approaches where fault related PVS power loss is evaluated. Research on infrared thermography (IRT) and luminescence imaging technologies is thoroughly reviewed, with focus on ease of implementation, efficiency and unmanned aerial system (UAS) compatibility. Furthermore, the review will provide novel insight into state-of-the-art electroluminescence (EL), photoluminescence (PL) and ultraviolet fluorescence (UVF) imaging, and how to interpret these images. The development of imaging techniques will continue to be an attractive domain of research that can be combined with aerial scanning for a cost-effective remote inspection that enable reliable power production in large-scale PV plants.

• Segbefia, Oscar Kwame; Imenes, Anne Gerd; Burud, Ingunn & Sætre, Tor Oskar (2021). Temperature profiles of field-aged multicrystalline silicon photovoltaic modules affected by microcracks. I Angus, Rockett (Red.), 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC). IEEE conference proceedings. ISSN 978-1-6654-1922-2. s. 0001–0006. doi: https:/doi.org/10.1109/PVSC43889.2021.9518939. Vis sammendrag

  In this work, the temperature sensitivities of field-aged multicrystalline silicon PV modules affected by microcracks are investigated. It is found that the temperature coefficient of efficiency of all modules has increased more than 10 times over the 20 years period, mainly due to a degradation in the temperature coefficients of fill factor. Temperature coefficient of efficiency of PV modules affected by microcracks changed from -0.44 %/ °C to -1.51 %/°C under solar irradiance conditions at 1010 - 1030 W/m 2. Inconsistent values for the Evans–Floschuetz efficiency ratio versus temperature plots for the microcrack affected modules were also observed.

• Valckenborg, Roland; Berger, Karl A.; Gusztáv, Újvári; Eder, Gabriele C.; Gaisberger, Lukas & Tabakovic, Momir [Vis alle 13 forfattere av denne artikkelen] (2021). Comparison of IEC 61853-1 Matrix Evaluations Based on Indoor and Outdoor Measurement Data from PVPS Task 15 BIPV Round-Robin, EU PVSEC 2021 – 38th European Photovoltaic Solar Energy Conference and Exhibition. EU PVSEC. ISSN 3-936338-78-7. s. 1381–1387. doi: 10.4229/EUPVSEC20212021-6DO.6.4. Vis sammendrag

  The international standard IEC 61853-1 contains two procedures for the evaluation of PV module output (Pmp) over a range of irradiances (GPOA) and module temperatures (Tmod): a procedure for indoor labs and a procedure for outdoor measurements (we neglect the option of using a tracker, which is quite challenging for BIPV-systems). The data from the IEA PVPS Task 15 (Enabling Framework for the Acceleration of Building Integrated Photovoltaics, BIPV) roundrobin has been used for an in-depth analysis of the differences between the indoor and outdoor determined Pmp-matrix. Moreover, the variety in the matrices of the eight individual test sites in various parts of the world is investigated. The approach is based on specific filtering of the outdoor data and color plot the relevant parameters in 2D matrices (of GPOA and Tmod) including the statistics of all data points that are present in each bin of that matrix. Filtering on Angle Of Incidence (AOI) and distance to center of the bin has been applied to make the comparison as precise as possible. Even after this filtering it was found impossible to decrease the standard deviation (stdev) of all points within a bin to a value lower than 5% as requested from the standard. A more realistic criterium of 10% stdev is proposed to use. The systematic fluctuations within each bin are caused by environmental factors that were not controlled or measured in our round-robin. These factors are, in random order: non-uniformity of (i) GPOA and (ii) Tmod within the module area, (iii) thermal dynamics between the Tmod sensor on the back of the PV-module and the actual Tcell that determines Pmp, (iv) soiling, (v) spectral effects. In conclusion, following the indoor and outdoor procedure of the IEC 61853-1 does not give the same Pmp-matrix for a given (BI)PV-module type. Significant differences are observed and analyzed. These results show that it might be very challenging to use the outdoor procedure without tracker for the purpose of energy rating. Leading to the recommendation to use the indoor procedure for energy rating of PV-modules and use the outdoor procedure for a well-defined quantification of energy losses caused by the aforementioned fluctuating environmental factors always present in realistic (BI)PV-systems.

• Imenes, Anne Gerd; Noori, Nadia Saad; Uthaug, Ole Andreas Nesvåg; Kröni, Robert; Bianchi, Filippo Maria & Belbachir, Nabil (2021). A Deep Learning Approach for Automated Fault Detection on Solar Modules Using Image Composites. I Angus, Rockett (Red.), 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC). IEEE conference proceedings. ISSN 978-1-6654-1922-2. doi: 10.1109/PVSC43889.2021.9518540. Vis sammendrag

  Aerial inspection of solar modules is becoming increasingly popular in automatizing operations and maintenance in large-scale photovoltaic power plants. Current practices are typically time-consuming as they make use of manual acquisitions and analysis of thousands of images to scan for faults and anomalies in the modules. In this paper, we explore and evaluate the use of computer vision and deep learning methods for automating the analysis of fault detection and classification in large scale photovoltaic module installations. We use convolutional neural networks to analyze thermal and visible color images acquired by cameras mounted on unmanned aerial vehicles. We generate composite images by overlaying the thermal and visible images to investigate improvements in detection accuracy of faint features related to faults on modules. Our main goal is to evaluate whether image processing with multi-wavelength composite images can improve both the detection and the classification performance compared to using thermal images alone. The hypothesis is that fusion of images acquired at different wavelengths (i.e., thermal infrared, red, green, and blue visible ranges) would enhance the multi-wavelength representation of faults and thus their histogram feature signatures. The results showed a successful detection and localization of faint fault features using composite images. However, the classification of the fault categories did not show significant improvements and needs continued investigation. This research represents a step towards the design of robust automated methods to improve fault detection from airborne images. Further work is still necessary to reach a classification accuracy comparable with the performance of human experts.

• Paudyal, Basant Raj & Imenes, Anne Gerd (2021). Uniqueness verification of blue fraction as a parameter of spectral irradiance quantification. I Angus, Rockett (Red.), 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC). IEEE conference proceedings. ISSN 978-1-6654-1922-2. Vis sammendrag

  The spectral distribution of global irradiance is measured in the optimal tilt (45° south) plane of array for the calender year 2020 in Grimstad, Norway. In this work the spectral distribution is quantified in terms of the Blue Fraction (BF). The uniqueness of BF has been tested and reported using the same methodology used for uniqueness verification of average photon energy (APE). The results show that the coefficient of correlation between the APE and BF was 0.98, meaning a possible bijective relation between these two parameters whereby both indicate a similar spectrum. The percentage contribution of integrated irradiance (Rc) was calculated for 25 nm wavelength bins for the BF region 350-650 nm. Spectra are grouped by their BF value in steps of 0.02, each group containing measurements falling within ±0.01 of the central value. The corresponding standard deviation (SD) varied from 0.05% to 0.21% for the spectra denoted by BF values from 0.44 to 0.60. The coefficient of variation (CV) was found as high as 12% for the wavelengths below 450 nm while it remained relatively low from 450-650 nm, meaning a low dispersion of Rc values around the mean value. The results indicate that the uniquenss of BF can be statistically confirmed for the measured wavelength range.

• Segbefia, Oscar Kwame; Imenes, Anne Gerd & Sætre, Tor Oskar (2021). Moisture ingress in photovoltaic modules: A review. Solar Energy. ISSN 0038-092X. 224, s. 889–906. doi: 10.1016/j.solener.2021.06.055. Fulltekst i vitenarkiv
• Paudyal, Basant Raj & Imenes, Anne Gerd (2021). Investigation of temperature coefficients of PV modules through field measured data. Solar Energy. ISSN 0038-092X. 224, s. 425–439. doi: 10.1016/j.solener.2021.06.013. Fulltekst i vitenarkiv
• Segbefia, Oscar Kwame; Imenes, Anne Gerd & Sætre, Tor Oskar (2020). Outdoor fault diagnosis of field-aged solar modules, European Photovoltaic Solar Energy Conference and Exhibition 37th EU PVSEC 2020. EU PVSEC. ISSN 3-936338-73-6.
• Paudyal, Basant Raj & Imenes, Anne Gerd (2020). Analysis of spectral irradiance distribution for PV applications at high latitude, 2020 47th IEEE Photovoltaic Specialists Conference (PVSC) . IEEE conference proceedings. ISSN 978-1-7281-6116-7. s. 1834–1841. doi: 10.1109/PVSC45281.2020.9300532.
• Reinders, Angele; van Slooten, Fjodor; Moser, David; van Sark, Wilfried; Oreski, Gernot & Ottersboeck, Bettina [Vis alle 13 forfattere av denne artikkelen] (2019). Development of a big data bank for PV monitoring data, analysis and simulation in COST Action ‘PEARL PV’. 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC). IEEE conference proceedings. ISSN 978-1-7281-0494-2. s. 1388–1392. doi: https:/doi.org/10.1109/PVSC40753.2019.8980650.
• Reinders, Angele; van Slooten, Fjodor; Moser, David; van Sark, Wilfried; Oreski, Gernot & Ottersboeck, Bettina [Vis alle 13 forfattere av denne artikkelen] (2019). Development of a big data bank for PV monitoring data, analysis and simulation in COST Action ‘PEARL PV’. I X, X (Red.), EU PVSEC 2019 (Marseille). 36th European Photovoltaic Solar Energy Conference And Exhibition. Proceedings . WIP. ISSN 3-936338-60-4. s. 1600–1604. doi: 10.1109/PVSC40753.2019.8980650.
• Paudyal, Basant Raj & Imenes, Anne Gerd (2019). Performance assessment of field deployed multi-crystalline PV modules in Nordic conditions . Conference record of the Photovoltaic Specialists Conference. ISSN 0160-8371. doi: 10.1109/PVSC40753.2019.8980629. Fulltekst i vitenarkiv
• Imenes, Anne Gerd & Selj, Josefine Helene Krogh (2018). Irradiance and Temperature Distributions at High Latitudes: Design Implications for Photovoltaic Systems, 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC). IEEE conference proceedings. ISSN 978-1-5090-5605-7. s. 619–625. doi: %2010.1109/PVSC.2017.8366376. Vis sammendrag

  — Irradiance and temperature distributions collected over several years at high-latitude locations in Norway (58-70°N) are presented. Measurements are coupled with standard efficiency data for selected commercial photovoltaic (PV) modules to evaluate the effect on relative efficiency. The modules display some performance variation caused by the different irradiance distributions, but the main effect is linked with temperature. The results may have implications for the choice of components and accuracy of yield estimates during the PV system design phase. The findings will provide input for the development of adapted building integrated (BIPV) modules with high performance and durability at high latitudes.

• Illich, P.; Eder, G.C.; Berger, K.A.; Ùjvàri, G.; Rechberger, P. & Moor, D. [Vis alle 22 forfattere av denne artikkelen] (2018). Comparative Performance Measurements of Identical BIPV-Elements in Different Climatic Environments - A Round Robin Action within the IEA PVPS Task 15 Collaboration. Proceedings of the European Photovoltaic Solar Energy Conference. ISSN 2196-100X. s. 1794–1800. doi: 10.4229/35thEUPVSEC20182018-6BV.1.32. Vis sammendrag

  This paper results from an on-going activity within the IEA PVPS Task 15 – Enabling Framework for the Acceleration of Building Integrated Photovoltaics (BIPV). It evaluates the performance of identical and commercially available glass/glass BIPV-elements installed in outdoor test sites at different climatic environments. These c-Si test-modules resemble those modules built in the façade of an existing reference building in Linz, Austria, and are mounted reproducing similar boundary conditions. The reference BIPV façade is currently under operation and has been monitored for more than 10 years. In total, the experiment involves 9 participants from 7 countries in Europe and Asia. Accorded monitoring method and constructive boundaries allow for the analysis of the influence of geographical and climatic conditions on the performance of the BIPV elements and can be related to the pre- and post-installation measurement results under STC conditions in a reference lab. From the experimental design of this work, it is possible to compare the performance results of a commercially available type of glass/glass BIPV elements installed in the façade of a building with those installed and monitored in outdoor-sites and measured under laboratory conditions. Furthermore, the reliability results under natural ageing conditions (high rise building with BIPV façade) are compared to those obtained after accelerated ageing in the laboratory. At this point, (incomplete) monitoring data of only six modules could be used for the first analysis. Thus, a detailed description of the the experimental design, the technical data of the laboratories, test sites and reference building and the current status of data analysis is presented.

• Paudyal, Basant Raj; Imenes, Anne Gerd & Sætre, Tor Oskar (2018). Review of Guidelines for PV Systems Performance and Degradations Monitoring. Proceedings of the European Photovoltaic Solar Energy Conference. ISSN 2196-100X. s. 2037–2050. doi: 10.4229/35thEUPVSEC20182018-6DV.1.32. Fulltekst i vitenarkiv Vis sammendrag

  The recent growth in the PV system deployment and the higher scale of their production make it necessary to pay more attention towards the performance of those systems. System monitoring will provide the status of the systems showing possible degradations and any impending system failures. It also helps with maintaining system quality and ensuring the optimal performance of the system for its lifetime. COST Action PEARL PV aims to formulate such monitoring guidelines for the PV systems applicable for all types of PV technologies, depending upon the end use and duration of the monitoring need. The objective of the present paper is to quantify and provide a review of the guidelines and standards for monitoring of PV systems performance and degradation in practice, and also some results of preliminary work done regarding important information needed to be included in the monitoring guideline.

• Sørensen, Åse Lekang; Imenes, Anne Gerd; Grynning, Steinar & Dokka, Tor Helge (2017). Energy measurements at Skarpnes zero energy homes in Southern Norway: Do the loads match up with the on-site energy production? Energy Procedia. ISSN 1876-6102. 132, s. 567–573. doi: 10.1016/j.egypro.2017.09.743. Fulltekst i vitenarkiv Vis sammendrag

  Five houses are designed as zero-energy homes in Skarpnes, Norway. The energy goal is to achieve net zero-energy balance on an annual basis. The houses have heat pumps and solar cells (PV). Energy use and delivered energy have been monitored from June 2015. Variations between calculations and measurements are explained by technical and non-technical reasons. For the first year, higher than expected energy loads result in a solar energy cover factor of 65–87% of delivered electricity. The PV generation performs satisfactorily, hence, it may be possible to achieve energy goals during later years provided technical adjustments or behavioral changes.

• Linjord, Torjus; O'Born, Reyn Joseph & Imenes, Anne Gerd (2017). Life cycle analysis of building integrated photovoltaic roof tile for use in Norwegian conditions. RIL. Suomen Rakennusinsinöörien Liitto. ISSN 0356-9403. s. 25–32. Vis sammendrag

  The main task in this study was to find the environmental impact of a photovoltaic (PV) roof tile for use in a Nordic climate with an interest in determining the energy payback time (EPBT) and global warming potential (GWP). A comparative life cycle assessment was conducted on two selected photovoltaic technologies used in Norway: a PV roof tile and a conventional PV panel. A total of five cases were examined in this analysis and the primary focus was on a monocrystalline PV roof tile, of which there were four different cases of the product. The fifth case in this study was an analysis on a conventional photovoltaic panel for baseline comparison purposes. Since there are no complete datasets available for the evaluation of annual performance of the PV roof tile, this was estimated for a location in Grimstad, Norway. The results of the study show that from an environmental perspective the use of conventional photovoltaics and building integrated photovoltaics are feasible solutions for the environment in Nordic climates.

• Fedorova, Anna; Jelle, Bjørn Petter; Andenæs, Erlend; Imenes, Anne Gerd; Aunrønning, Ole & Schlemminger, Christian [Vis alle 7 forfattere av denne artikkelen] (2017). Large-Scale Laboratory Investigation of Building Integrated Photovoltaics - A Review of Methods and Opportunities. I Kalogirou, Soteris A. & Kennedy, David (Red.), Proceedings of 1st International Conference on Building Integrated Renewable Energy Systems (BIRES 2017). Dublin Institute of Technology (DIT) Ireland. ISSN 978-9963-697-23-6.
• Imenes, Anne Gerd & Kanters, Jouri (2016). 3D Solar Maps for the Evaluation of Building Integrated Photovoltaics in Future City Districts: a Norwegian Case Study, IEEE 43rd Photovoltaic Specialists Conference 2016 (PVSC). IEEE Press. ISSN 978-1-5090-2724-8. s. 3141–3146. doi: 10.1109/PVSC.2016.7750245. Vis sammendrag

  Three-dimensional (3D) solar maps based on Radiance simulations are presented for a future city district in southern Norway. The surface mapping method provides the commercial developer with a practical tool to evaluate the potential for building integrated photovoltaics (BIPV). The solar maps identify the optimum roof and facade areas available for solar energy utilization. The importance of BIPV and facade utilization in new city developments is discussed, along with key questions raised by the commercial developer regarding the practical implementation of BIPV solutions. Based on feedback from the building industry, a simplified model has been implemented to evaluate surface areas producing a profit or a loss over the PV system lifetime. As tilted photovoltaic (PV) modules installed on flat roofs are not building integrated, three simulation variants have been performed for flat roofs with a small inclination up to ten degrees. For some buildings this will give a small gain in annual PV production and payback time. The resulting 3D solar maps give the developer a possibility to review early-stage plans in terms of building shapes and positions in the landscape, in order to maximize utilization of the available solar resource. This enables cost-and energy-efficient development of nearly zero-energy buildings in future city districts.

• Imenes, Anne Gerd (2016). Performance of Zero Energy Homes in Smart Village Skarpnes, IEEE 43rd Photovoltaic Specialists Conference 2016 (PVSC). IEEE Press. ISSN 978-1-5090-2724-8. s. 3153–3158. doi: 10.1109/PVSC.2016.7750247. Vis sammendrag

  In Smart Village Skarpnes in southern Norway, five detached houses are designed as zero energy homes. This work reports on the photovoltaic (PV) power production and energy consumption behavior of these homes and discusses whether an annual zero energy budget may be achieved. Results so far indicate that the extremely low annual energy consumption assumed for these types of homes may be difficult to achieve, and also point at a need for better matching between production and consumption power profiles. Performance results are based on monitoring data combined with estimated performances from PVsyst simulations. The work is part of a larger research project that investigates how the introduction of low-energy buildings equipped with PV systems is expected to change the power flow to and from the grid, which will require new models for efficient operation and investment in the future electric distribution grid.

• Imenes, Anne Gerd (2016). Performance of BIPV and BAPV Installations in Norway, IEEE 43rd Photovoltaic Specialists Conference 2016 (PVSC). IEEE Press. ISSN 978-1-5090-2724-8. s. 3147–3152. doi: 10.1109/PVSC.2016.7750246. Vis sammendrag

  The research community and stakeholders in the building sector seek information on the performance and reliability of PV systems in the built environment and the best solutions for maximum energy production. This paper presents results from collected information on a representative selection of existing building integrated (BIPV) and building applied (BAPV) photovoltaic systems in Norway. The work is part of a national project that aims at developing robust BIPV-solutions suitable for a Norwegian climate. The project also aims at identifying the main building-technical and architectural integration challenges for BIPV. A questionnaire has been developed to interview key personnel involved in the design, installation and operational phases, and a database is under development to build a wider knowledge base for the expected performances of different system types and geographical locations. Performance is evaluated in terms of energy production, specific yield, and performance ratio (PR) in cases where irradiation data is available. Data collected so far indicate a relatively large spread in annual specific yield with typical values in the 700-900 kWh/kWp range. A well-functioning system without significant shading may achieve PR above 0.85, in agreement with similar findings for Europe. Five selected cases are presented in more detail. The lessons learned provide useful input for the development of new guidelines and system requirements for BIPV in a Nordic climate.

• Azmi, Aimie Nazmin Bin; Dahlberg, Ivan N.; Kolhe, Mohan Lal & Imenes, Anne Gerd (2016). Impact of Increasing Penetration of Photovoltaic (PV) Systems on Distribution Feeders, 2015 International Conference on Smart Grid and Clean Energy Technologies. IEEE conference proceedings. ISSN 978-1-4673-8734-7. s. 70–74. doi: 10.1109/ICSGCE.2015.7454271.
• Imenes, Anne Gerd; Beyer, Hans-Georg; Boysen, Kjetil Rostoft; Odden, Jan Ove & Grundt, Rolf Erlend (2015). Performance of grid-connected PV system in Southern Norway, 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC 2015). Curran Associates, Inc.. ISSN 9781479979431. doi: 10.1109/PVSC.2015.7355823. Vis sammendrag

  This paper presents performance results from one of the first grid-connected photovoltaic (PV) systems in Norway. The 45 kWp system is mounted on top of a flat roof at the headquarters of a local utility company, Agder Energi, in the coastal town of Kristiansand. The system consists mainly of multi-crystalline silicon modules, with one thin film array. The system has been in operation since May 2011 and is instrumented for research and monitoring purposes. Data recorded include global and diffuse horizontal irradiation, tilted irradiation and other weather parameters, PV module temperatures, DC and AC current and voltage for three arrays, in addition to inverter power data and voltage quality measurements. Similar performance data has not yet been published for Norway. The results so far indicate good conditions for solar utilization at this location with global horizontal irradiation around 1065 W/(m2yr) and around 50 % diffuse fraction. The system produces as expected from a design perspective, with specific yield reaching 950 kWh/kWp and PR approaching 0.8 in 2014. Improvement in PR is seen as operational experience increases and system downtime is reduced. PR loss can be attributed to part-shading of PV arrays from the surrounding building structures, snow coverage in winter and inverter outages.

• Azmi, Aimie Nazmin Bin; Kolhe, Mohan Lal & Imenes, Anne Gerd (2015). Review on Photovoltaic Based Active Generator, The 9th International Symposium on Advanced Topics in Electrical Engineering. Curran Associates, Inc.. ISSN 9781479975150. s. 812–815. doi: 10.1109/ATEE.2015.7133914.
• Beyer, Hans-Georg & Imenes, Anne Gerd (2015). Influence of the Quality of Irradiance Forecasts to the Performance of Forecast Based Control of Grid-connected PV-Systems with Storage, 5th Solar Integration Workshop International Workshop on Integrating of Solar Power into Power Systems. Energynautics GmbH. ISSN 978-3-9816549-2-9.
• Beyer, Hans-Georg & Imenes, Anne Gerd (2015). Influence of the Inclusion of Storage in Grid-Connected Domestic PV-Systems on the Predictability of the Power Exchange with the Grid. Proceedings of the European Photovoltaic Solar Energy Conference. ISSN 2196-100X. 2015, s. 2770–2773. doi: 10.4229/EUPVSEC20152015-6AV.4.14.

Se alle arbeider i Cristin

• Imenes, Anne Gerd (2024). FME SOLAR - UiA's Role in a National Collaborative Effort for the Green Transition. Vis sammendrag

  UiA is a partner in the newly established FME SOLAR, a national center for environmentally friendly energy research. What is the purpose of the center, why is it necessary, and how can UiA contribute? The presentation will provide an overview of the planned R&D activities over the next eight years and explore the opportunities for UiA to contribute through outstanding research and education by involving various skills across our departments.

• Dahlioui, Dounia & Imenes, Anne Gerd (2024). Snow Impact on PV Performance: Review and Investigation Towards Optimum System Design. Vis sammendrag

  PV technology faces certain challenges in cold climates such as snow and ice acting as barriers, obstructing light from reaching the cells, but also opportunities for increased albedo during snowy winters. This work presents two sections highlighting : ▪ A review of the impact of snow on PV performance focusing on the challenges and opportunities posed by snow accumulation. ▪ Distribution of snow losses across various PV technologies and climate zones, as reported in literature. ▪ Analysis and classification of factors influencing snow losses. ▪ Description of snow soiling process. ▪ Parametric analysis of energy yield and snow losses to tilt angle and ground coverage ratio through production modelling using Solar Advisor Model (SAM) for a case study in Grimstad

• Larsen, Baard; Tømte, Thomas; Olsen, Susann Haga; Nielsen, Henrik Kofoed; Imenes, Anne Gerd & Paul, Alexander (2023). Kan ha stor betydning for framtiden. [Avis]. Grimstad Adressetidende. Vis sammendrag

  Aldri tidligere har energibruk og energioptimalisering av kirker blitt kartlagt på denne måten. Nå jobber to studenter ved UiA med å se på mulighetene som finnes.

• Imenes, Anne Gerd (2023). Klimakrise og energikrise: Kan sola være løsningen?
• Imenes, Anne Gerd (2023). Klimakrise og energikrise: Kan sola være løsningen?
• Imenes, Anne Gerd (2023). Kan sola redde oss fra energikrisen?
• Imenes, Anne Gerd (2023). Klimakrise og energikrise: Kan sola være løsningen?
• Imenes, Anne Gerd (2023). Solenergi.
• Imenes, Anne Gerd (2023). Kan sola redde oss fra energikrisen? Vis sammendrag

  Sola gir oss mer enn nok energi for vårt behov i all framtid. Hvordan klarer vi å utnytte denne energien? Er det realistisk å tenke seg en framtid med bare direkte og ren solenergi? Foredraget vil forsøke å belyse disse dagsaktuelle spørsmålene og fortelle litt om hva det forskes på innen feltet solcelleteknologi ved Universitetet i Agder.

• Strandberg, Rune & Imenes, Anne Gerd (2023). Efficiency maps for tandem solar cells using high resolution spectral data.
• Strandberg, Rune & Imenes, Anne Gerd (2022). Production estimates for tandem cells using high resolution spectral data.
• Imenes, Anne Gerd (2022). The Terawatt challenge: The key role of PV monitoring. Vis sammendrag

  As the installation of new PV capacity continues to grow at a rapid rate worldwide, expected to rise from today’s 4% of the global electricity production to almost 15% by 2030, the value of and need for PV monitoring will arguably increase in a corresponding manner. Monitoring data represent the main source of information for the evaluation of economic profitability, system operation strategies, and environmental sustainability of PV power systems. This work will discuss the need for PV monitoring towards the Terawatt transition, including important international work on PV monitoring and databases, standards and guidelines for methods and equipment, data requirements of different user groups, challenges of data access and data quality, further work needed, and consideration of trends for future data collection from various sources of PV monitoring data and as it crosses borderlines with health inspection and diagnostic tools. Examples of the collection and sharing of data as part of collaborative work in the COST Action PEARL PV on Performance and Reliability of PV Systems will be given.

• Imenes, Anne Gerd (2022). The Terawatt challenge: Why do we need PV monitoring?
• Imenes, Anne Gerd & Kubens, Valerie (2022). Solenergi kan bli like stort som vannkraft. [Avis]. Fedrelandsvennen.
• Imenes, Anne Gerd & Kallestad, Jarle (2022). Kirke og universitet samarbeider i kampen mot strømkrisen. [Avis]. Dagen.
• Imenes, Anne Gerd (2022). Kan sola redde oss fra energikrisen?
• Imenes, Anne Gerd (2022). Sola - Kan den redde oss fra energikrisen?
• Imenes, Anne Gerd (2022). Kan sola redde oss fra energikrisen?
• Imenes, Anne Gerd (2022). Kan sola redde oss fra energikrisen?
• Imenes, Anne Gerd (2022). Den store energidagen: Solenergi. Vis sammendrag

  Nye teknologier kan bidra til å redde oss fra klimakrisen, men også her oppstår konflikter, og det må gjøres avveininger. Forskere på UiA vil ha korte innlegg om ulike typer fornybar energi og hva det forskes på ved UiA. Hva går de ulike formene ut på, og hvilke muligheter og begrensinger har de?

• Imenes, Anne Gerd & Rød, Benjamin (2022). Solsagt: Anne Gerd Imenes, UiA: Bachelor og master i fornybar energi. [Internett]. https://podcasts.apple.com/us/podcast/solsagt/id1503995163. Vis sammendrag

  På UiA kan du studere til bachelor eller master i fornybar energi. Kappløpet om å finne de beste energiløsningene er i full gang. Energibransjen står overfor store utfordringer og investeringsbehov. Du kan bli med å virkeliggjøre visjonen om et energinøytralt Europa. Solsagt - en Podcast serie fra Solenergiklyngen: I møte med konjunktursvingninger vil konkurransedyktige bedrifter etterspørre mer kompetanse. Med en masterutdanning står du sterkere overfor endringer i arbeidsmarkedet. Studiet er internasjonalt rettet, og studenter kan bli engasjert i pågående forskningsprosjekter. Anne Gerd har selv lang erfaring med solenergi, ikke minst fra Australia der hun har jobbet med consentraded solar power.

• Imenes, Anne Gerd & Ulfig, Karolina (2022). Dette er utsiktene for miljøvennlig utvikling av sørlandsbyer. [Avis]. Avisen Agder Flekkefjords Tidende.
• Imenes, Anne Gerd & Rød, Benjamin (2021). Solsagt av Solenergiklyngen, 2021-12-13. Anne Gerd Imenes, UiA: Bachelor og master i fornybar energi. [Internett]. https://podtail.com/da/podcast/solenergiklyngen/.
• Høiaas, Ingeborg; Vukovic, Marija; Jakovljevic, Marko; Burud, Ingunn; Olsen, Espen & Imenes, Anne Gerd (2021). Comparison of Imaging Techniques for PV Module Inspection in the Field. Vis sammendrag

  A comprehensive PV module diagnosis can be reached by combining several imaging technologies such as infrared thermography (IRT) imaging and ultraviolet fluorescence (UVF). Other novel luminescence technologies such as electroluminescence (EL) and photoluminescence (PL) show great potential but require further development to be utilized in a large-scale inspection system. The development of imaging techniques will continue to be an attractive domain of research that can be combined with aerial scanning for a cost-effective remote inspection that enable reliable power production in large-scale PV plants.

• Imenes, Anne Gerd; Noori, Nadia Saad; Uthaug, Ole Andreas Nesvåg; Kröni, Robert; Bianchi, Filippo Maria & Belbachir, Nabil (2021). A Deep Learning Approach for Automated Fault Detection on Solar Modules Using Image Composites. Vis sammendrag

  Aerial inspection of solar modules is becoming increasingly popular in automatizing operations and maintenance in large-scale photovoltaic power plants. Current practices are typically time-consuming as they make use of manual acquisitions and analysis of thousands of images to scan for faults and anomalies in the modules. In this paper, we explore and evaluate the use of computer vision and deep learning methods for automating the analysis of fault detection and classification in large scale photovoltaic module installations. We use convolutional neural networks to analyze thermal and visible color images acquired by cameras mounted on unmanned aerial vehicles. We generate composite images by overlaying the thermal and visible images to investigate improvements in detection accuracy of faint features related to faults on modules. Our main goal is to evaluate whether image processing with multi-wavelength composite images can improve both the detection and the classification performance compared to using thermal images alone. The hypothesis is that fusion of images acquired at different wavelengths (i.e., thermal infrared, red, green, and blue visible ranges) would enhance the multi-wavelength representation of faults and thus their histogram feature signatures. The results showed a successful detection and localization of faint fault features using composite images. However, the classification of the fault categories did not show significant improvements and needs continued investigation. This research represents a step towards the design of robust automated methods to improve fault detection from airborne images. Further work is still necessary to reach a classification accuracy comparable with the performance of human experts.

• Paudyal, Basant Raj & Imenes, Anne Gerd (2021). Uniqueness verification of blue fraction as a parameter of spectral irradiance quantification. Vis sammendrag

  The spectral distribution of global irradiance is measured in the optimal tilt (45° south) plane of array for the calender year 2020 in Grimstad, Norway. In this work the spectral distribution is quantified in terms of the Blue Fraction (BF). The uniqueness of BF has been tested and reported using the same methodology used for uniqueness verification of average photon energy (APE). The results show that the coefficient of correlation between the APE and BF was 0.98, meaning a possible bijective relation between these two parameters whereby both indicate a similar spectrum. The percentage contribution of integrated irradiance (Rc) was calculated for 25 nm wavelength bins for the BF region 350-650 nm. Spectra are grouped by their BF value in steps of 0.02, each group containing measurements falling within ±0.01 of the central value. The corresponding standard deviation (SD) varied from 0.05% to 0.21% for the spectra denoted by BF values from 0.44 to 0.60. The coefficient of variation (CV) was found as high as 12% for the wavelengths below 450 nm while it remained relatively low from 450-650 nm, meaning a low dispersion of Rc values around the mean value. The results indicate that the uniquenss of BF can be statistically confirmed for the measured wavelength range.

• Paudyal, Basant Raj & Imenes, Anne Gerd (2020). Outdoor PV Monitoring: Results from Grimstad.
• Imenes, Anne Gerd (2020). Country Report Norway. I Farkas, Istvan; Atsu, Divine; Raghoebarsing, Amrita; Boddaert, Simon; Moser, David & Reinders, Angele (Red.), PEARL PV Country Reports. COST Action CA16235. Performance and Reliability of Photovoltaic Systems : Evaluations of Large-Scale Monitoring Data. University of Twente. ISSN 978-90-365-5108-3. s. 180–190. doi: 10.3990/1.9789036551083.
• Imenes, Anne Gerd (2020). Skarpnes Village, Arendal. I Reijenga, Tjerk; Ritzen, Michiel; Scognamiglio, Alessandra; Kappel, Karin & Frontini, Francesco (Red.), Successful Building Integration of Photovoltaics – A Collection of International Projects. IEA PVPS TCP. ISSN 978-3-906042-92-3. s. 196–203.
• Imenes, Anne Gerd (2020). Solsmaragden Offices, Drammen. I Reijenga, Tjerk; Ritzen, Michiel; Scognamiglio, Alessandra; Kappel, Karin & Frontini, Francesco (Red.), Successful Building Integration of Photovoltaics – A Collection of International Projects. IEA PVPS TCP. ISSN 978-3-906042-92-3. s. 138–146.
• Imenes, Anne Gerd (2020). Brynseng Primary School. I Reijenga, Tjerk; Ritzen, Michiel; Scognamiglio, Alessandra; Kappel, Karin & Frontini, Francesco (Red.), Successful Building Integration of Photovoltaics – A Collection of International Projects. IEA PVPS TCP. ISSN 978-3-906042-92-3. s. 36–44.
• Paudyal, Basant Raj & Imenes, Anne Gerd (2020). Analysis of spectral irradiance distribution for PV applications at high latitude.
• Imenes, Anne Gerd (2020). Kan sola redde oss fra energikrisen?
• Imenes, Anne Gerd (2020). Kan sola redde oss fra energikrisen? Og hva forsker vi på ved solcellegruppen ved UiA?
• Reinders, Angele; van Slooten, Fjodor; Moser, David; van Sark, Wilfried; Oreski, Gernot & Ottersboeck, Bettina [Vis alle 13 forfattere av denne artikkelen] (2019). Development of a big data bank for PV monitoring data, analysis and simulation in COST Action ‘PEARL PV’.
• Paudyal, Basant Raj & Imenes, Anne Gerd (2019). Outdoor monitoring of spectral irradiance for PV module performance testing.
• Imenes, Anne Gerd (2019). Kan sola redde oss fra energikrisen? Vis sammendrag

  Sola gir oss mer enn nok energi for vårt behov i all framtid. Hvordan klarer vi å utnytte denne energien? Er det realistisk å tenke seg en framtid med bare direkte og ren solenergi?

• Paudyal, Basant Raj & Imenes, Anne Gerd (2019). Performance assessment of field deployed multi-crystalline PV modules in Nordic conditions .
• Paudyal, Basant Raj; Imenes, Anne Gerd & Sætre, Tor Oskar (2018). Review of Guidelines for PV Systems Performance and Degradations Monitoring. Vis sammendrag

  The recent growth in the PV system deployment and the higher scale of their production make it necessary to pay more attention towards the performance of those systems. System monitoring will provide the status of the systems showing possible degradations and any impending system failures. It also helps with maintaining system quality and ensuring the optimal performance of the system for its lifetime. COST Action PEARL PV aims to formulate such monitoring guidelines for the PV systems applicable for all types of PV technologies, depending upon the end use and duration of the monitoring need. The objective of the present paper is to quantify and provide a review of the guidelines and standards for monitoring of PV systems performance and degradation in practice, and also some results of preliminary work done regarding important information needed to be included in the monitoring guideline.

• Illich, P.; Eder, G.C.; Berger, K.A.; Ùjvàri, G.; Rechberger, P. & Moor, D. [Vis alle 22 forfattere av denne artikkelen] (2018). Comparative Performance Measurements of Identical BIPV-Elements in Different Climatic Environments - A Round Robin Action within the IEA PVPS Task 15 Collaboration.
• Imenes, Anne Gerd (2018). Monitoring of PV System Performance and Degradation.
• Imenes, Anne Gerd; Jelle, Bjørn Petter; Selj, Josefine Helene Krogh; Foss, Sean Erik; Marstein, Erik Stensrud & Kolås, Tore (2017). Building integrated photovoltaics for Norway: System installation options and the effect on performance.
• Imenes, Anne Gerd (2017). Building integrated photovoltaics: Examples from Norway.
• Imenes, Anne Gerd & Selj, Josefine (2017). Irradiance and temperature distributions at high latitudes: Design implications for photovoltaic systems. Vis sammendrag

  Irradiance and temperature distributions collected over several years at high-latitude locations in Norway (58-70°N) are presented. Measurements are coupled with standard efficiency data for selected commercial photovoltaic (PV) modules to evaluate the effect on relative efficiency. The modules display some performance variation caused by the different irradiance distributions, but the main effect is linked with temperature. The results may have implications for the choice of components and accuracy of yield estimates during the PV system design phase. The findings will provide input for the development of adapted building integrated (BIPV) modules with high performance and durability at high latitudes.

• Sørnes, Kari; Tunheim, Ketil; Sartori, Igor & Imenes, Anne Gerd (2017). The impact of resolution on load matching in a Norwegian context. Fulltekst i vitenarkiv
• Sørensen, Åse Lekang; Imenes, Anne Gerd; Grynning, Steinar & Dokka, Tor Helge (2017). Energy measurements at Skarpnes zero energy homes in Southern Norway: Do the loads match up with the on-site energy production?
• Beyer, Hans Georg; Imenes, Anne Gerd & Hategikimana, pascal (2017). Der Beitrag von PV-Anlagen zur Energie- und Leistungsbilanz einer Nullenergiehaussiedlung in Südnorwegen – Einfluss des Lastprofils und Optmierungsmöglichkeiten.
• Fedorova, Anna; Jelle, Bjørn Petter; Andenæs, Erlend; Imenes, Anne Gerd; Aunrønning, Ole & Schlemminger, Christian [Vis alle 7 forfattere av denne artikkelen] (2017). Large-Scale Laboratory Investigation of Building Integrated Photovoltaics - A Review of Methods and Opportunities.
• Imenes, Anne Gerd (2016). Solar Powered Science. Vis sammendrag

  Why solar makes sense; Important R&D topics for a growing global market; Performance testing: Outdoor lab at UiA Grimstad; 'Real-life' testing on grid-connected system: Agder Energi, Kjøita Kristiansand; The reality of results; What's in it for us?; Do we dare to compare?; Enabling the green shift: Cleaner - better - smarter!

• Imenes, Anne Gerd (2016). Performance of BIPV and BAPV Installations in Norway. Vis sammendrag

  The research community and stakeholders in the building sector seek information on the performance and reliability of PV systems in the built environment and the best solutions for maximum energy production. This paper presents results from collected information on a representative selection of existing building integrated (BIPV) and building applied (BAPV) photovoltaic systems in Norway. The work is part of a national project that aims at developing robust BIPV-solutions suitable for a Norwegian climate. The project also aims at identifying the main building-technical and architectural integration challenges for BIPV. A questionnaire has been developed to interview key personnel involved in the design, installation and operational phases, and a database is under development to build a wider knowledge base for the expected performances of different system types and geographical locations. Performance is evaluated in terms of energy production, specific yield, and performance ratio (PR) in cases where irradiation data is available. Data collected so far indicate a relatively large spread in annual specific yield with typical values in the 700-900 kWh/kWp range. A well-functioning system without significant shading may achieve PR above 0.85, in agreement with similar findings for Europe. Five selected cases are presented in more detail. The lessons learned provide useful input for the development of new guidelines and system requirements for BIPV in a Nordic climate.

• Imenes, Anne Gerd & Kanters, Jouri (2016). 3D Solar Maps for the Evaluation of Building Integrated Photovoltaics in Future City Districts: a Norwegian Case Study. Vis sammendrag

  Three-dimensional (3D) solar maps based on Radiance simulations are presented for a future city district in southern Norway. The surface mapping method provides the commercial developer with a practical tool to evaluate the potential for building integrated photovoltaics (BIPV). The solar maps identify the optimum roof and facade areas available for solar energy utilization. The importance of BIPV and facade utilization in new city developments is discussed, along with key questions raised by the commercial developer regarding the practical implementation of BIPV solutions. Based on feedback from the building industry, a simplified model has been implemented to evaluate surface areas producing a profit or a loss over the PV system lifetime. As tilted photovoltaic (PV) modules installed on flat roofs are not building integrated, three simulation variants have been performed for flat roofs with a small inclination up to ten degrees. For some buildings this will give a small gain in annual PV production and payback time. The resulting 3D solar maps give the developer a possibility to review early-stage plans in terms of building shapes and positions in the landscape, in order to maximize utilization of the available solar resource. This enables cost-and energy-efficient development of nearly zero-energy buildings in future city districts.

• Imenes, Anne Gerd (2016). Performance of Zero Energy Homes in Smart Village Skarpnes. Vis sammendrag

  In Smart Village Skarpnes in southern Norway, five detached houses are designed as zero energy homes. This work reports on the photovoltaic (PV) power production and energy consumption behavior of these homes and discusses whether an annual zero energy budget may be achieved. Results so far indicate that the extremely low annual energy consumption assumed for these types of homes may be difficult to achieve, and also point at a need for better matching between production and consumption power profiles. Performance results are based on monitoring data combined with estimated performances from PVsyst simulations. The work is part of a larger research project that investigates how the introduction of low-energy buildings equipped with PV systems is expected to change the power flow to and from the grid, which will require new models for efficient operation and investment in the future electric distribution grid.

• Jelle, Bjørn Petter; Kolås, Tore; Schlemminger, Christian; Schlanbusch, Reidun Dahl; Imenes, Anne Gerd & Selj, Josefine Helene [Vis alle 8 forfattere av denne artikkelen] (2016). Building Integrated Photovoltaics for Norway.
• Imenes, Anne Gerd (2015). BIPVNO webpage: Building Integrated Photovoltaics for Norway.
• Imenes, Anne Gerd (2015). Bygningsintegrerte solcelleanlegg.
• Imenes, Anne Gerd; Aasland, Dag Gjerløw; Bjørnestøl, Katharina Reionn; Grelland, Hans Herlof & Steen-Johnsen, Tale (2023). Bærekraftanalyse for Metochi. Universitetet i Agder.
• Tømte, Thomas; Nielsen, Henrik Kofoed & Imenes, Anne Gerd (2023). Preserving the past, powering the future: Energy efficiency and renewables in Norway's wooden churches. Universitetet i Agder. Vis sammendrag

  This master’s thesis explores the potential for energy efficiency in three wooden churches built in the 19th century in the southern part of Norway. Specifically, the thesis focuses on the three churches Eide, Landvik, and Grimstad, all owned and operated by the Grimstad Church Council. Each church presents its own unique set of challenges related to heating and overall energy efficiency, largely due to their varying sizes. The thesis examines the impact of various energy efficiency measures and explores the possibilities of implementing renewable energy systems such as solar panels and geothermal energy. At Eide church, three different configurations of solar panel systems have been studied, and the thesis also considers how the implementation of a battery can increase self-consumption of the church’s electricity production. PVsyst has been used to simulate these alternatives. The thesis highlights potential energy savings in the range of 30-50% by lowering the temper- ature, making simple structural upgrades, and upgrading the heating control system in an annex adjacent to the church. A combination of solar panels and energy efficiency measures could make the church energy positive. In Landvik church, the energy calculation program Simien has been used to assess the effects of various energy efficiency measures. Among the measures mentioned are retrofitting of roof, wall, and floor insulation, window replacement, lighting system upgrades, and temperature reduction. The results show that the church can achieve annual energy savings of up to 40% of the current energy consumption by combining multiple measures. Furthermore, this master’s thesis suggests that implementing a 25.5 kW liquid-to-water heat pump in Grimstad church, supplied from two energy wells, could cover 90% of the church’s energy consumption and thus save an equivalent proportion of biofuel oil, over 13 000 liters annually. The thesis identifies a significant need to educate and inform the church’s staff about energy efficiency and points out that too much responsibility is placed on those working for the church’s daily operations. Based on the large number of churches in Norway, the results of this study have significant transferability, and the potential for energy savings at a national and Nordic level is consid- erable. In conclusion, the thesis emphasizes that the approach requires a balance between advanced technologies, awareness, and basic practices.

• Krebs Kristiansen, Martin & Imenes, Anne Gerd (2023). Performance analysis of PV power plants across Norway. Universitetet i Agder. Vis sammendrag

  This thesis examines hourly aggregated data from 501 photovoltaic (PV) installations, builds a better knowledge foundation about the geographical performance of PV systems in Norway, and provides a groundwork for how PV datasets with limited metadata can be analyzed. Metadata is supplemented with inferred tilt and azimuth by analyzing the power and irradiance relationship at different orientations, with 1-degree intervals. When tested with a known PV installation, the result shows a median accuracy of 12.2 and 14.1 degrees for tilt and azimuth, respectively. To analyze the performance of PV installations, the power output data is filtered with a linear filter (RANSAC) and a non-linear polynomial filter. The latter shows promising results, as long as specific requirements regarding the number of available timestamps are available. Unknown capacity units are inferred by selecting highly probable units (Wp, kW_p, and MW_p) and finding highly probable specific yields. Installations, where highly probable specific yields are not found using these units have been removed from further analysis.

• Ulven, Adrian Bjørge & Imenes, Anne Gerd (2023). Analysis of spectral irradiance variations and their impact on the performance of different photovoltaic modules. Universitetet i Agder. Vis sammendrag

  This thesis analyzes two years of global horizontal spectral irradiance and global tilted spectral irradiance data to see how the spectral distribution varies over these years. In addition, an attempt will be made to estimate the energy yield from four different PV modules using two years of global horizontal and angled spectral radiation. These modules are a c-Si module, an a-Si module, a CdTe module, and a CIGS module. Initially, the task was to test a hand-held spectrometer and be compared with a stationary spectrometer. Due to a defective calibration instrument, this could not be investigated further, and the main focus of the thesis was moved to the spectral data. An average spectral distribution for each month was created except for the months that were missing from the data set. The energy yield for the four PV modules was estimated through a Python script. The energy yield that was calculated turned out to be incorrect due to an error in the data processing in the method section. The measurements of the CIGS PV modules were also off due to their high performance compared to the other modules.

• Larsen, Sigrid Langholm & Imenes, Anne Gerd (2021). Investigation of Outdoor Performance of Silicon Photovoltaic Modules at Different Installation Angles. Universitetet i Agder. Vis sammendrag

  The objective of this master thesis is to analyse and compare the performance of two different PV technologies mounted at different tilt angles and orientations. The PV modules are installed on the roof of the J5 building in the University of Agder, located in Grimstad, Norway. The analysis was carried out by comparing 13 months of measured data (from March 2020 to March 2021). The technologies assessed are mono crystalline silicon and poly crystalline silicon, mounted at a tilt angle of 10 deg East/West, 45 deg South and 90 deg South. Data recorded include global and diffuse horizontal irradiance, irradiance in the plane-of-array and other weather parameters, PV module temperature, DC output power, current and voltage for the PV modules. To assess the performance, performance ratio, temperature corrected performance ratio and specific yield has been calculated for all modules on a monthly basis. Results give the DC specific yield for 10 deg tilt modules between 920 - 984 kWh/kWp. The two modules mounted on the 45 deg tilt rack and the BIPV modules all had low data availability due to missing data points. To account for this data are estimated for the missing data point using linear regression. The DC specific yield before estimating data for missing data points for 45 deg are 988 kWh/kWp (mono c-Si 45 deg), 1050 kWh/kWp (poly c-Si 45 deg), 762 kWh/kWp (BIPV normal), and 760 kWh/kWp (BIPV grey). Comparing the two PV technologies at different tilt angles and orientations, there is not detected a substantial difference in performance between the East- and West-facing modules at a 10 deg tilt. The PR for the higher tilted modules are on average slightly better than for the 10 deg tilt modules. The best indication of module performance in the various installation angles are when estimating output power for missing data. From these results the PRDC values of the 10 deg tilt modules are in the range 0.88 - 0.90 (mono c-Si E/W) and 0.88-0.92 (poly c-Si W/E), while for the 45 deg tilt modules the values are 0.92 (mono c-Si) and 0.95 (poly c-Si), and for both the normal and grey BIPV modules at 90 deg tilt the value is 0.94. PVsyst software is used to simulate five mono c-Si modules at 10 deg tilt and East-facing. This is because in the system at UiA five modules are connected in a string to one inverter. Design parameters such as module tilt, orientation, shading and inter-row spacing is defined to obtain as accurate simulation as possible. The results show a good correlation between simulation and calculated results. AC energy output for the simulation was 1436 kWh/year, compared to DC output for the real system at 1451 kWh/year. PVsyst simulation can be used to investigate other installation angles and orientations than the ones analysed in this work.

• Aigner, Birk Ludwig Schoder; Imenes, Anne Gerd & Skomedal, Gunstein (2021). System modeling and dispatch schedule optimization of combined PV battery system using linear optimization. Universitetet i Agder. Vis sammendrag

  Energy storage plays a vital role in paving the way for more renewable penetration. The technology is costly, but intelligent solutions regarding dispatch strategies and system design can help reduce the total cost over the projected lifetime of a system. For this thesis, a customizable linear programming algorithm is created within Python to optimize the battery energy scheduling based on generated PV power, electricity cost and load demand. The commercial system optimization tool HOMER is used to verify the code by running simulations based on historic data collected from NordPool and UiAs own photovoltaic system. One benefit of the custom made code is its ability to do day-ahead optimization utilizing data from APIs. To obtain forecasted irradiation and temperature data the Solcast API was used as the only paid service for the Python script to ensure market-leading accuracy. Electricity prices were imported from the transparency platform Entsoe. Implementing different incentives such as battery energy throughput and stored energy made it possible to alter the system behavior to optimize the system better while maintaining good working conditions for the battery. Carefully choosing the optimization parameters reduced battery cycling by 45.9% and average energy stored by 34.8% in two separate scenarios while maintaining cost savings. The case studied uses a power tariff power plan which means that the primary cost savings from including a battery come from peak shaving.

• Nese, Ole-Kristian Minde & Imenes, Anne Gerd (2020). Investigation of a PV System Using a Mathematical Model and Available Data . Universitetet i Agder. Vis sammendrag

  In this paper the investigation of a grid connected photovoltaic (PV) system equipped with module level DC-DC power optimizers is presented. The objective of this thesis is to investigate a PV system in a variety of mismatch conditions by creating a mathematical model with the ability to simulate it and to use this model to investigate the performance. The model will also in part be used to try and answer a research question, namely: Is it beneficial to equip a PV system with moduel level DC-DC power optimizers as opposed to a traditional string inverter with maximum power point tracking (MPPT). A mathematical model was build based on an existing model and data regarding the PV system was collected from tigo.com were the power optimizers reports a value every minute. The system was found to respond well to a number of mismatch conditions, mitigating them very successfully. However, in one instance the power optimizers were unable to allow the unaffected modules of a string to generate energy. Finally it was concluded that power optimizers have their benefit in a PV system, even without much mismatch. For further investigation of the system several new experiments and economics calculations could be performed.

• Ommundsen, Simen; Imenes, Anne Gerd; Bilal, Muhammad & Paudyal, Basant Raj (2019). Testing and Analysis of Building-Integrated Photovoltaics in Southern Norway. Universitetet i Agder.
• Lie, Camilla; Imenes, Anne Gerd; Leal, J B & Sathyajith, Mathew (2019). Power Prediction of Photovoltaic System using Neural Network Models. Universitetet i Agder. Vis sammendrag

  This work considers a photovoltaic (PV) system installed on the rooftop of Agder Energi’s headquarters located at Kjøita, Kristiansand. The system includes three different types of solar PV modules; Suntech (multi-Si), Sharp (a-Si/μ-Si) and REC (multi-Si), that have a total installed DC capacity of 45 kWp. The system is grid-connected and instrumented for research and monitoring purposes. Artificial Neural Network (ANN) models were trained to obtain the lowest mean square error (MSE), by testing different configurations using a model-based trial and error approach. The model configurations that gave the lowest (MSE) were used to predict the power production from each of the PV modules using forecasted weather parameters obtained from MEPS (MetCoOp Ensemble Prediction System), with a one-day ahead and two-days ahead forecast horizon. The input selection of the models was based on both model-free and model-based approach, where the final input selection resulted in global horizontal irradiance, wind speed, air temperature and air mass, with the power (AC) production as output (target). The results indicated that the model configurations of 20 hidden neurons in first hidden layer, and 2 hidden neurons in second hidden layer gave the lowest MSE for all PV modules. Results from the test sets showed that the best model for Suntech gave MSE = 0.0454, Sharp gave MSE = 0.0325 and REC gave MSE = 0.0492. R2-values between 0.95 and 0.96 were obtained for all three models, indicating good fitting of the predicted values and the targets. Testing the Suntech and REC models with a hold-out set provided slightly less precise predictions compared to the results from the test set, while a higher precision was found for Sharp modules. Testing the model configurations with forecasted weather parameters indicated that the forecast accuracy of the weather will influence the power prediction, and the performance parameters will be accordingly. The one-day ahead forecasts provided MSE equal to 0.2647, 0.2378 and 0.2647, and for the two-days ahead forecast horizon an MSE equal to 0.2996, 0.2252 and 0.2719 for Suntech, Sharp and REC, respectively. An error much higher compared to the test set and hold-out set for the models, which inevitably was expected due to the weather forecast uncertainties. Based on the findings in this work, it can be concluded that a further optimization of the models will be necessary before obtaining even more precise predictions. However, the models did show good fitting for several days and a potential for using ANN models for power prediction of PV modules.

• Mace, Philippe; Larsson, David; Benson, Jessica; Woess-Gallasch, Susanne; Kappel, Karin & Frederiksen, Kenn [Vis alle 16 forfattere av denne artikkelen] (2018). Transition Towards Sound BIPV Business Models - Inventory on Existing Business Models, Opportunities and Issues for BIPV. International Energy Agency (IEA). ISSN 978-3-906042-70-1. Vis sammendrag

  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. 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.

• Imenes, Anne Gerd & Birkeland, Rune (2018). Modelling and simulation of BIPV installations in Norway. Universitetet i Agder.
• Imenes, Anne Gerd; Berthod, Charly; Kråkenes, Ciaran & Jensen, Ingrid Rosland (2018). Performance Degradation and Failure Analysis of 7 Years of Field Exposed Photovoltaic System in Southern Norway. Universitetet i Agder.
• Imenes, Anne Gerd; Wold, Margrethe & Hasla, Helene Arnesen (2018). Measurements and Analysis of Spectral Irradiance Distributions in Southern Norway. Universitetet i Agder.
• Imenes, Anne Gerd & Frivold, Christian Hals (2018). Photovoltaic facade systems in Norway: An assessment of energy performance, building integration, and costs. Universitetet i Agder.
• Nazmin, Aimie; Kolhe, Mohan Lal & Imenes, Anne Gerd (2017). Grid Interaction Performance Evaluation of BIPV and Analysis with Energy Storage on Distributed Network Power Management. Universitetet i Agder. Vis sammendrag

  This research focuses on analysis of photovoltaic (PV) based active generator in microgrid and its utilization in not only for operational planning of the power system but also for instantaneous power flow management in the smart grid environment. The application of this system is part of a solution on handling a large scale deployment of grid connected distributed generators, especially PV system. By implementing the PV based active generator, it will be very flexible able to manage the power delivery from the active generator sources (e.g. PV system, energy storage technologies, active power conditioning devices). In Southern Norway, a smart village Skarpnes is developed for ZEBs. These ZEBs have Building Integrated Photovoltaic (BIPV) system. The energy efficient housing development should consider that a building should produce the same amount of electrical energy as its annual requirements (i.e. ZEB). In future, ZEBs are going to play a significant role in the upcoming smart grid development due to their contribution on the on-site electrical generation, energy storage, demand side management etc. In this work the main objective is to evaluate the usefulness of ZEBs for load matching with BIPV generation profiles and grid interaction analysis. Impact of BIPV system has been investigated on the distributed network power flow as well as on protection and protective relays analysis. Furthermore, techno-economic analysis of BIPV system is presented which will be useful to the utility for developing new business models as well as demand side management (DSM) strategies and for decentralized energy storage. The real operational results of a year are analyzed for annual energy balance with on-site BIPV generation and local load. This work provides quantitative analysis of various grid interaction parameters suitable to describe energy performance of the BIPV. The load matching and grid interaction parameters are calculated for a house to find relationship of BIPV generation and building load. The loss of load probability is analyzed for fulfilling the local load at desired reliability level. Results of this work are going to be useful for developing DSM strategies and energy storage as well as import/export energy to the grid. This work will be beneficial for future planning of the distributed network when the BIPV penetrations are going to increase.

• Imenes, Anne Gerd; Hageengen, Fredrik & Thorud, Bjørn (2016). Feasibility Study of Photovoltaic Noise Barriers in Norway. Universitetet i Agder.
• Linjord, Torjus; O'Born, Reyn Joseph & Imenes, Anne Gerd (2016). Life cycle analysis of photovoltaic roof tile. Universitetet i Agder.

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