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Karlsson, Björn O.
Alternative names
Publications (10 of 15) Show all publications
Cabral, D. & Karlsson, B. O. (2018). Electrical and thermal performance evaluation of symmetric truncated C-PVT trough solar collectors with vertical bifacial receivers. Solar Energy, 174, 683-690
Open this publication in new window or tab >>Electrical and thermal performance evaluation of symmetric truncated C-PVT trough solar collectors with vertical bifacial receivers
2018 (English)In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 174, p. 683-690Article in journal (Refereed) Published
Abstract [en]

One way to reduce solar collectors’ production costs is to use concentrators that increase the output per photovoltaic cell. Concentrating collectors re-direct solar radiation that passes through an aperture into an absorber/receiver. Symmetrical truncated non-tracking C-PVT trough collectors based on a parabola and compound parabolic concentrator (CPC) geometries have been developed. The collector type has a central vertical bifacial (fin) receiver and it was optimized for lower latitudes. In this paper, the electrical and thermal performance of symmetric truncated non-tracking low concentrator PVT solar collectors with vertical bifacial receivers is analysed, through a numerical ray-tracing model software and a multi-paradigm numerical computing environment. A thermal (quasi-dynamic testing method for liquid heating collectors described in the international standard for solar thermal collectors ISO 9806:2013) and electrical performance models were implemented to evaluate the design concepts. The evaluation was made for heating Domestic Hot Water for a Single Family House in Fayoum (Egypt), where CPC geometries with a concentration factor of 1.6 achieved 8 to 13%rel higher energy yields (in kWh/m2/year) than the Pure Parabola geometries.

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Bifacial receiver, Electrical and thermal yield evaluation, Ray-tracing, Symmetric C-PVT collector
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-28322 (URN)10.1016/j.solener.2018.09.045 (DOI)000451499500065 ()2-s2.0-85053808056 (Scopus ID)
Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2019-01-07Bibliographically approved
Gallardo-Saavedra, S. & Karlsson, B. O. (2018). Simulation, validation and analysis of shading effects on a PV system. Solar Energy, 170, 828-839
Open this publication in new window or tab >>Simulation, validation and analysis of shading effects on a PV system
2018 (English)In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 170, p. 828-839Article in journal (Refereed) Published
Abstract [en]

A simulation program for calculating the IV-curve for series connected PV-modules during partial shadowing has been developed and experimentally validated. The software used for modelling the modules is LTspice IV. The validation has been done by means of a comparative analysis using the experimental results obtained in a set of tests performed on the mono-crystalline modules of the Gävle University's laboratory in Sweden. Experimental measurements were carried out in two groups. The first group is a string of six modules with bypass diodes while the second one corresponds to a single PV module. The simulation results of both groups demonstrated a remarkable agreement with the experimental data, which means that the designed model can be used for simulating the influence of shading on the power of a string. The model has been used for analysing the performance of strings of PV modules with shadows and the benefits of installing DC-DC optimizers or module inverters, that minimise the impact of shading, have been investigated.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Bypass diode, DC-DC optimizer, PV modelling, Single-diode
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-27356 (URN)10.1016/j.solener.2018.06.035 (DOI)000442713900076 ()2-s2.0-85048298570 (Scopus ID)
Funder
Swedish Energy Agency
Note

Funding information:

Applied PV research and development program SoEl

Swedish industries through Energiforsk

Available from: 2018-06-25 Created: 2018-06-25 Last updated: 2018-09-14Bibliographically approved
Gustafsson, M., Karlsson, B. & Rönnelid, M. (2017). How the electric meter configuration affect the monitored amount of self-consumed and produced excess electricity from PV systems: case study in Sweden. Energy and Buildings, 138, 60-68
Open this publication in new window or tab >>How the electric meter configuration affect the monitored amount of self-consumed and produced excess electricity from PV systems: case study in Sweden
2017 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 138, p. 60-68Article in journal (Refereed) Published
Abstract [en]

This study evaluates how the principal function of bi-directional electric meters affects the monitored amount of self-consumed and produced excess electricity for dwelling buildings connected to the grid by three phases. The electric meters momentarily record the sum of the phases or the phases individually and then summarize the recorded values to a suitable time period and is then collected by the grid owner. In Sweden, both electric meter configurations fulfill laws and regulations.

The meter configuration affects the monitored distribution of self-consumed and produced excess electricity significantly for the investigated single-family house but is negligible for the investigated multi-dwelling buildings. The monitored self-consumed electricity produced by the PV installation for the single-family house varies between 24% and 55% depending on the configuration and how the inverter is installed for the investigated year. The difference in economic value for the produced electricity varies between 79.3 to 142 Euros.

Due to the electric meter configuration, the profitability of PV systems will be different for identical single-family houses with identical conditions. This should be corrected for a well-functioning market. It is also important to decide how the configuration should be designed to ensure that different incentives and enablers results in desired effects.

Keywords
Buildings, Commerce, Electric measuring instruments, Electric power generation, Energy policy, Houses, Housing, Laws and legislation, Energy markets, Identical conditions, Laws and regulations, Principal functions, PV installations, PV system, Single-family house, Solar PVs, Electric power transmission networks
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-21397 (URN)10.1016/j.enbuild.2016.11.010 (DOI)000394061200006 ()2-s2.0-85006846894 (Scopus ID)
Funder
Knowledge Foundation
Note

The work has been carried out under the auspices of the industrial post-graduate school Reesbe, which is financed by the Knowledge Foundation (KK-stiftelsen).

Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2018-10-01Bibliographically approved
Cabral, D., Gomes, J., Dostie-Guindon, P.-A. & Karlsson, B. O. (2017). Ray tracing simulations of a novel low concentrator PVT solar collector for low latitudes. In: ISES Solar World Congress 2017 - IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2017, Proceedings: . Paper presented at SWC 2017: ISES Solar World Congress, SHC 2017: IEA SHC Solar Heating and Cooling Conference 2017; 29 October - 2 November 2017, Abu Dhabi, UAE (pp. 1068-1079). International Solar Energy Society
Open this publication in new window or tab >>Ray tracing simulations of a novel low concentrator PVT solar collector for low latitudes
2017 (English)In: ISES Solar World Congress 2017 - IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2017, Proceedings, International Solar Energy Society , 2017, p. 1068-1079Conference paper, Published paper (Refereed)
Abstract [en]

One way to reduce solar collector's production costs is to use concentrators that increase the output per photovoltaic cell. Concentrating collectors re-direct solar radiation that passes through an aperture into an absorber. The current study evaluates electrical performance of symmetric C-PVT solar collectors with a vertical bifacial receiver, through a numerical ray tracing model software, Tonatiuh. Several designs have been analysed, such as the Pure Parabola (PP) and MaReCo CPC geometries, both symmetric. Parameters such as concentration factor, electrical performance, transversal and longitudinal IAM (Incidence Angle Modifier), the influence of optical elements and influence of the length of the reflector in the shadow effect have been studied for different geometries. The simulations were performed for Mogadishu, Somalia and showed good results for the Pure Parabola collector (PPc) annual received energy, 379 and 317 kWh/m2/year for a focal length of 15 e 30 mm, respectively. A symmetrical double MaReCo CPC collector has been simulated with the annual received energy of 315 kWh/m2/year. The addition of the optical elements will decrease the annual received energy of the PPc by around 11.5%, where the optical properties (7.1%) and glass (4.1%) have the biggest impact in the annual received energy. Overall, symmetric geometries proved to be the most suitable geometries for low latitudes applications, being the geometry f1 (focal length of 15 mm) the best one. 

Place, publisher, year, edition, pages
International Solar Energy Society, 2017
Keywords
MaReCo CPC geometry, Pure Parabola collector, Symmetric C-PVT, Tonatiuh, C (programming language), Geometry, Optical properties, Photoelectrochemical cells, Photovoltaic cells, Rhenium compounds, Solar collectors, Solar heating, Solar power generation, Solar radiation, Concentrating collector, Concentration factors, Direct solar radiation, Electrical performance, Ray tracing simulation, Ray tracing
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-27631 (URN)10.18086/swc.2017.18.05 (DOI)2-s2.0-85050544604 (Scopus ID)978-3-9814659-7-6 (ISBN)
Conference
SWC 2017: ISES Solar World Congress, SHC 2017: IEA SHC Solar Heating and Cooling Conference 2017; 29 October - 2 November 2017, Abu Dhabi, UAE
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-13Bibliographically approved
Gustafsson, M., Thygesen, R., Karlsson, B. & Ödlund, L. (2017). Rev-Changes in Primary Energy Use and CO2 Emissions: An Impact Assessment for a Building with Focus on the Swedish Proposal for Nearly Zero Energy Buildings. Energies, 10(7), Article ID 978.
Open this publication in new window or tab >>Rev-Changes in Primary Energy Use and CO2 Emissions: An Impact Assessment for a Building with Focus on the Swedish Proposal for Nearly Zero Energy Buildings
2017 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 7, article id 978Article in journal (Refereed) Published
Abstract [en]

In the European Union's Energy Performance of Buildings Directive, the energy efficiency goal for buildings is set in terms of primary energy use. In the proposal from the National Board of Housing, Building, and Planning, for nearly zero energy buildings in Sweden, the use of primary energy is expressed as a primary energy number calculated with given primary energy factors. In this article, a multi-dwelling building is simulated and the difference in the primary energy number is investigated when the building uses heat from district heating systems or from heat pumps, alone or combined with solar thermal or solar photovoltaic systems. It is also investigated how the global CO2 emissions are influenced by the different energy system combinations and with different fuels used. It is concluded that the calculated primary energy number is lower for heat pump systems, but the global CO2 emissions are lowest when district heating uses mostly biofuels and is combined with solar PV systems. The difference is up to 140 tonnes/year. If the aim with the Swedish building code is to decrease the global CO2 emissions then the ratio between the primary energy factors for electricity and heat should be larger than three and considerably higher than today.

Keywords
Emissions (Air pollution), Building, Energy consumption, Dwellings, Heat pumps, decentralized energy generation systems, district heating, energy performance of buildings, heat pump, primary energy, primary energy factors
National Category
Energy Engineering
Identifiers
urn:nbn:se:hig:diva-24872 (URN)10.3390/en10070978 (DOI)000406700200149 ()2-s2.0-85042470517 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2017-08-17 Created: 2017-08-17 Last updated: 2018-10-01Bibliographically approved
Francisco Contero, J., Gomes, J., Gustafsson, M. & Karlsson, B. O. (2017). The impact of shading in the performance of three different solar PV systems. In: PROCEEDINGS OF THE 11TH ISES EUROSUN 2016 CONFERENCE: . Paper presented at 11th ISES EuroSun Conference, 11-14 October 2017, Palma, Spain (pp. 1168-1179). INTL SOLAR ENERGY SOC
Open this publication in new window or tab >>The impact of shading in the performance of three different solar PV systems
2017 (English)In: PROCEEDINGS OF THE 11TH ISES EUROSUN 2016 CONFERENCE, INTL SOLAR ENERGY SOC , 2017, p. 1168-1179Conference paper, Published paper (Refereed)
Abstract [en]

Partial shading decreases the performance of PV modules due to the series connection between the solar cells. In the recent years, several new technologies have emerged within the photovoltaics field to mitigate the effect of shading in the performance of the PV modules. For an accurate assessment of the performance of these devices, it is required to evaluate them comparatively in different circumstances. Three systems with six series-connected PV modules (each containing 60 cells) have been installed at the University of Gavle. System One comprises a string inverter system with 6 PV modules; System Two features a DC-DC optimizer per panel and a string inverter; System Three incorporates three micro inverters for six modules. A major conclusion of this study was that under partial shading of one (or more) modules both System Two (DC-DC optimizers) and System Three (micro inverters) perform considerably better than System One (string inverter), as long as the Impp of the shadowed module is lower than the Impp of the unshaded string It is also important that the Vmpp in the shaded module is higher than the lowest allowed voltage of the DC-DC optimizer or module inverter. The economic implications of the usage of these devices were also analyzed.

Place, publisher, year, edition, pages
INTL SOLAR ENERGY SOC, 2017
Keywords
Shading; PV-cells; DC-DC; inverter; installation; Impp; Vmpp; Pmax
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-26397 (URN)10.18086/eurosun.2016.08.25 (DOI)000426895100118 ()
Conference
11th ISES EuroSun Conference, 11-14 October 2017, Palma, Spain
Funder
Swedish Energy Agency
Available from: 2018-04-03 Created: 2018-04-03 Last updated: 2018-06-26Bibliographically approved
Gustafsson, M., Rönnelid, M., Trygg, L. & Karlsson, B. (2016). CO2 emission evaluation of energy conserving measures in buildings connected to a district heating system: case study of a multi-dwelling building in Sweden. Energy, 111, 341-350
Open this publication in new window or tab >>CO2 emission evaluation of energy conserving measures in buildings connected to a district heating system: case study of a multi-dwelling building in Sweden
2016 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 111, p. 341-350Article in journal (Refereed) Published
Abstract [en]

When taking action to fulfill the directives from the European Union, energy conserving measures will be implemented in the building sector. If buildings are connected to district heating systems, a reduced heat demand will influence the electricity production if the reduced heat demand is covered by combined heat and power plants.

This study analyze five different energy conserving measures in a multi-dwelling building regarding how they affect the marginal production units in the district heating system in Gävle, Sweden. For CO2 emission evaluations, two different combinations of heat and electricity conserving measures are compared to an installation of an exhaust air heat pump.

The different energy conserving measures affect the district heating system in different ways. The results show that installing an exhaust air heat pump affects the use/production of electricity in the district heating system most and electricity conserving measures result in reduced use of electricity in the building, reduced use of electricity for production of heat in the district heating system and an increase of electricity production.

The conclusion is that electricity use in the building is the most important factor to consider when energy conserving measures are introduced in buildings within the district heating system in Gävle.

Keywords
District heating system, Energy efficiency, Greenhouse gases, Refurbishment, Simulation
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-21396 (URN)10.1016/j.energy.2016.05.002 (DOI)000384776900029 ()2-s2.0-84973177469 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2018-10-01Bibliographically approved
Contero, F., Gomes, J., Gustafsson, M. & Karlsson, B. O. (2016). The impact of shading in the performance of threee different solar PV systems. In: : . Paper presented at 11th ISES Eurosun 2016, International Conference on Solar Energy for Buildings and Industry, 11-14 October 2016, Palma, Mallorca.
Open this publication in new window or tab >>The impact of shading in the performance of threee different solar PV systems
2016 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-25761 (URN)
Conference
11th ISES Eurosun 2016, International Conference on Solar Energy for Buildings and Industry, 11-14 October 2016, Palma, Mallorca
Available from: 2017-12-07 Created: 2017-12-07 Last updated: 2018-03-13Bibliographically approved
Mantei, F., Henriques, M., Gomes, J., Olsson, O. & Karlsson, B. (2015). The night cooling effect on a C-PVT solar collector. In: ISES Solar World Congress 2015, Conference Proceedings: . Paper presented at International Solar Energy Society, ISES Solar World Congress 2015, SWC 2015, 8-12 November 2017, EXCODaegu, South Korea (pp. 1167-1175). International Solar Energy Society
Open this publication in new window or tab >>The night cooling effect on a C-PVT solar collector
Show others...
2015 (English)In: ISES Solar World Congress 2015, Conference Proceedings, International Solar Energy Society, 2015, p. 1167-1175Conference paper, Published paper (Refereed)
Abstract [en]

Night cooling consists in running a fluid through a solar panel during the night in order to reduce the fluid temperature which can be used for cooling applications. Radiative heat losses can allow the fluid to reach temperatures below ambient while conduction and convection works to equalize the collector with the ambient temperature. This paper analyzes the possibility of using an asymmetric concentrating photovoltaic thermal solar collector (C-PVT) for cooling applications during the night by losing heat through convection, conduction and irradiation. The cooling performance of the C-PVT collector has been measured during the night at different inlet temperatures in the interval of 13 to 38°C which corresponded to a AT (between the collector average and the ambient) from 6 to 28°C. The performance of the tested C-PVT collector has been measured at different inlet temperatures in an interval of 13 to 38°C. During all performed measurements, the radiation losses did not drive the collector temperature below ambient temperature. With high AT (between the inlet and the ambient) of 30°C, a 1,85°C temperature decrease in the fluid was obtained. For AT of 14°C, the temperature decrease was only 0,88°C. The measurements showed a night U-value for the Solarus C-PVT of 4,2 W/m2K This correlates well with previous papers showing measurements taken during the day. Heat losses seem to be dominated by convection and conduction due to the existence of the glass in the collector. Despite this, a measurable relation between heat losses and cloudiness factor exists. This shows that the irradiance losses are not negligible. Only very specific applications can be suited for night cooling with this collector design, since it is not so common to have applications that require low grade cooling during the night time or justify storing this energy. However, if the C-PVT design was made without a glass cover, the results could potentially be very different for locations with many clear nights.

Place, publisher, year, edition, pages
International Solar Energy Society, 2015
Keywords
Asymmetric collector, Collector testing, Concentrating PVT, CPC-collector, Night cooling, Glass, Heat convection, Heat losses, Solar collectors, Solar energy, Solar power generation, Temperature, Asymmetric collectors, CPC collectors, Cooling
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-25747 (URN)10.18086/swc.2015.10.33 (DOI)2-s2.0-85016956998 (Scopus ID)9783981465952 (ISBN)
Conference
International Solar Energy Society, ISES Solar World Congress 2015, SWC 2015, 8-12 November 2017, EXCODaegu, South Korea
Available from: 2017-12-06 Created: 2017-12-06 Last updated: 2018-03-13Bibliographically approved
Davidsson, H., Bernardo, R., Gomes, J., Gentile, N., Gruffman, C., Chea, L. & Karlsson, B. (2014). Construction of laboratories for solar energy research in developing countries. Paper presented at 2013 ISES Solar World Congress, 3-7 November 2013, Cancún, Mexico. Energy Procedia, 57, 982-988
Open this publication in new window or tab >>Construction of laboratories for solar energy research in developing countries
Show others...
2014 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 57, p. 982-988Article in journal (Refereed) Published
Abstract [en]

A large number of PV-systems have been installed in developing countries around the world duringnumerous projects. The aim is often to improve the quality of life in rural areas, often lacking electricity.Many of these installations provide important services such as lighting and charging of different devices.However, when the projects are finished, there is a large risk that maintenance is not carried out properlyand that malfunctions are never repaired. This situation can leave an otherwise well functioning systemunusable. A key problem is that there are not enough trained technicians that can maintain and repair thesystem locally. One reason to this is the lack of practical education in many developing countries.Furthermore, the availability of spare parts is essential for the long term effectiveness.During 2011 a group of researchers from Lund University in Sweden built a small scale laboratory inMaputo, Mozambique, together with local researchers. The project was successful and today thelaboratory functions both as a teaching facility and as a measurement station for solar energy research forlicentiates, masters and PhD students.The main goal is now to widen the project in order to incorporate more universities in developingcountries. We are now looking for new interested partners in developing countries that believe that such alaboratory could strengthen their possibility to teach practical work and to perform research at the localuniversity. Partners for planning and executing the project are also needed.

Keywords
Sustainable Development; Solar Laboratory; Research and Education
National Category
Energy Systems
Identifiers
urn:nbn:se:hig:diva-18535 (URN)10.1016/j.egypro.2014.10.081 (DOI)
Conference
2013 ISES Solar World Congress, 3-7 November 2013, Cancún, Mexico
Available from: 2014-12-13 Created: 2014-12-13 Last updated: 2018-03-28Bibliographically approved
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