SmartSol²

Smart Solar hybrid Solutions for sustainable European buildings

Summary (1 page)

Achieving the ambitious national goals in Swedish building sector are impossible without a smart, cost-effective, scalable, and integrated solution for heating, cooling and electricity. The combination of solar PV/thermal collectors and ground source heat pumps are a scalable sustainable energy alternative for Swedish neighborhoods. This project aims to make heating, cooling, and electricity micro-districts more cost effective by developing solar PV/thermal collectors specifically designed for GSHP integration, optimizing the micro-district system, and verifying the performance in pilot installations.

The project focuses on both component and system development and optimization. At the component level, the collector must be improved from design, material, and production perspectives. A computational fluid dynamics (CFD) model of the collector is developed and validated against the lab measurement results. Then the CFD model will be used to evaluate the possible improvements. After evaluation and analysis of several hypothetical improvements, the most effective modifications, from both technical and economic perspectives, will be identified and implemented physically. Consequently, the new prototype will be developed both physically and digitally by KTH and Sunhybrid.

At the system level, a holistic dynamic model is further developed including the solar PV/Thermal collector, brine to water heat pump unit, ground borehole heat exchanger field, thermal storage, a residential district made of several multi-family house buildings (which incorporates the dynamic electrical, heating and cooling demand), parasitic losses (liquid pumps and fans), heating distributions systems, etc. A system model has already been developed by KTH in TRNSYS (Transient System Simulation Tool) which needs further improvement as well as validation. The holistic model is used as a powerful tool to evaluate the dynamic behavior of the system under a large variety of conditions e.g. different mass flow rates, different load conditions, and borehole field configurations.

The TRNSYS system modeling and dynamic simulation finally leads to size and parameter optimization and more importantly development of smart control strategies to maximize solar energy utilization and economic performance. Following the results and conclusions from system modeling and simulation, KTH, Sunhybrid and Sonority build the prototype of an integrated system solution to be tested in real life condition. The last but not least part of the project is dedicated to the in-situ field measurement and the integrated system prototype. The results from this part will be used for further understanding of the system behavior, system optimization, as well as validation of the dynamic model of the system. Field measurements and model validation are two interconnected parallel processes that support each other iteratively for system optimization.

The project ultimately aims to increase renewable utilization and low-carbon energy sources in Swedish multi-family houses towards meeting national energy targets. The in-house competence to be built during the project will help the Swedish industry to pioneer in innovative combination of two promising energy technologies, ground source heat pump and solar PV/Thermal technologies.

Project Description (8 pages max)

Motivation

Sweden has some of the most ambitious energy and climate goals in the world, however, the district heating sector is lagging in reduction of greenhouse gas emissions. 85% of heat is sourced from combusted fuels, which leads to 76 g/kWh_thof CO2 equivalent (Energiföretagen, 2018). By comparison, the Nordic electricity supply has some of the lowest emissions in the world at 47 g/kWh_el(Moro and Lonza, 2018). When the electricity is converted into heat with a heat pump, the emission for heat supply can be reduced to 12-16 g/kWh_th, an 80% reduction as compared to district heating.

Over 90% of multi-family houses (MFH) are connected to district heating networks (Energimyndigheten (Swedish Energy Agency), 2019). While it is indeed a convenient solution, it is often their only choice. This leaves them at the mercy of price rises and fuel sources decided by the heating providers. If a building owner wants to switch to heat pumps, they run into several challenges stemming from the densely populated areas most common to MFH:

• a lack of land for boreholes with ground source heat pumps (GSHP)
• noisy heat exchangers with air source heat pumps (ASHP), and
• older buildings often lack suitable ventilation systems for exhaust air heat pumps.

Older buildings also tend to have the greatest heating demands and thus should be highlighted for retrofit. For example, Miljonprogrammet buildings account for 25% of the Swedish housing stock, requiring 8800 GWh of heat and emitting 670,000 tons of CO2 (equivalent) annually (Energiföretagen, 2018; Swedish Energy Agency, 2015).

A promising pathway to the electrification of MFH are solar heat pumps (SHP). There are numerous methods for combining the two technologies, however one increasingly interesting approach is the integration of photovoltaic/thermal (PVT) hybrid collectors with GSHP in a series configuration, shown in Figure 1. The main benefit of this approach is the reduction of borehole count, spacing, or both in combination, decreasing the amount of land needed for boreholes up to 87% (Sommerfeldt and Madani, 2019). The low temperatures used in a borehole circuit are beneficial for the PVT modules as well; the cooler PV cells become more efficient and produce enough additional electricity to cover the additional pumping power, making the additional thermal gains energetically free.

Recent cost reductions have dramatically increased the solar PV market in Sweden, mostly in buildings (Lindahl et al., 2019). PVT collectors have virtually no market share in comparison, in Sweden or elsewhere, and the PVT+GSHP concept is at a very early stage in commercialization. This project is motivated by the potential for the SHP concept to scale and decarbonize the building sector in Sweden and Europe, and the remainder of the description will;

• review the state-of-the-art in research and development,
• identify knowledge gaps and corresponding objectives of this project,
• introduce the partners, their interests, motivations, and relevance,
• the approach planned for meeting the objectives, and
• outline the impact of a successful project on society, industry and academia.

Figure 1– PVT+GSHP concept with PVT connected in series

Background

The foundation for this project stems primarily from two recently completed projects – the Mistra Innovation project “Sunhybrid” (number MI15.18) led by Solhybrid i Småland and the Effsys Expand project “Ground Source Heat Pumps for Swedish Multi-Family Houses: Innovative Co-Generation and Thermal Storage Strategies” (number 40936-1) led by KTH.

The Mistra project was dedicated to modeling and development of a PVT collector specifically for heat pump integration. Results were generated using a combination of modeling and collector testing. Numerous insights into heat exchanger design were gained, such as ideal flow patterns and collector construction, and a validated model of the second generation design was generated for use in systems analysis. An early prototype of a third generation design was constructed, however more work is needed to get a working version. A short summary of the project outcomes can be found on the Mistra Innovation website and is listed in the references (Johansson, 2018).

Historically, PVT collectors used typical solar thermal collector designs based on the sheet-and-tube configuration with PV cells applied to the absorber plate. They were designed to operate between 40-70°C, however high temperatures during stagnation led to accelerated degradation and delamination of the PV cells (Brahim and Jemni, 2017; Zondag, 2008; Zondag et al., 2005). In response, most manufacturers have moved to mechanically pressing the heat exchanger to the rear of standard PV module, which increases thermal resistance and lowers efficiency. By increasing the surface area of the working fluid in contact with the absorber, such as with a roll-bond technique, the heat transfer can be increased, but at a greater cost of production (Bombarda et al., 2016).

PVT efficiency and lifetimes are also increased with reduced operating temperatures(Brahim and Jemni, 2017; Jordan and Kurtz, 2013), such as when they are integrated with heat pumps and boreholes. The proposed PVT design is relatively inefficient at traditional operating temperatures, however the low temperatures in a borehole circuit (-5 to 20 °C) boost productivity to a level on par with a high performance solar thermal system (Sommerfeldt and Madani, 2018; Weiss and Spörk-Dür, 2018). This is because about 50% of the thermal gains come from the air rather than solar radiation, even without any forced convection aside from the wind. The cooler PV cells also produce more electricity, enough to cover the additional circulation pump demand, thus making the collected heat a free resource (Sommerfeldt and Madani, 2019). In total, this PVT collector produces 3x more energy than the PV module alone.

The Effsys Expand project was dedicated to systems modeling of PVT hybrid GSHP systems. Results were generated by developing a detailed model of the complete system, including; a typical Swedish multi-family house (like those from the miljonprogrammet), GSHP, a borehole field, solar PV and PVT, and thermal storage. Dynamic simulations were carried out in the powerful modeling tool TRNSYS, where the impact of PVT collectors on energy and economic performance is demonstrated theoretically. Sample results from an MFH in Stockholm are given in Figure 2which show where the PVT thermal energy is delivered in the system over the year (left) and how that impacts the boreholes (right). Approximately 55% of the PVT thermal energy is delivered while the heat pump is running, and the rest is injected into the boreholes. This regenerates the ground temperatures after the heating season and between June and August the heat pump is capable of operating exclusively on PVT. Over the whole year, 20% of the total heat supplied to evaporator comes from the solar collectors.

Figure 2– PVT thermal energy distribution (left) and borehole energy balance (right)

The numerous design variables make strict rules of thumb difficult to state, however with a full-roof of PVT collectors supporting the boreholes the total drilling length can be reduced by about 20% while maintaining a similar seasonal performance factor. When pushed to the extreme, the borehole length could be reduced by 65% before the heat pump evaporator temperature limits are reached. Another option is to reduce borehole spacing, potentially saving up to 87% of the land area required for drilling. A PV-only system with a traditionally sized borehole field was found to have a lower life cycle cost, however PVT+GSHP has a lower cost than district heating, making the concept particularly interesting for properties with limited land resources. The final report is available online at the Effsys Expand website and is listed in the references (Sommerfeldt and Madani, 2018).

The benefits of a combined heat and power solution using PVT and GSHP systems are most compelling and cost effective in large systems. First, the technical and economic benefits of a reduced borehole length are much greater in a larger system than a single-family house where there is only one borehole and the marginal cost of drilling is lower. Second, the high efficiency of a PVT collector has more value on a roof with limited space, and they have long been considered more useful for multi-family houses or commercial buildings than single-family homes (Zondag, 2008). And finally, the complicated installation of a solar hydraulic system has a high fixed cost that can be absorbed by a larger system, making the final cost of heat much lower than in single-family homes (Weiss and Spörk-Dür, 2018).

Research into PVT based solar heat pump systems has been rising in the past 10 years, in particular as a secondary heat source for GSHP (Kamel et al., 2015; Poppi et al., 2018; Sommerfeldt and Madani, 2016). As the two leading countries in GSHP installations, Sweden and Switzerland have also been leading in the technique with PVT in multiple demonstration and research projects (Good et al., 2015). In addition to the applicant’s Mistra Innovation and Effsys Expand projects, Research Institutes of Sweden (RISE) recently completed a study monitoring and simulating a PVT+GSHP system near Gothenburg, coming to similar conclusions about borehole field reduction potential (Benson et al., 2018; Gervind et al., 2016). In addition to the industrial partners in this project, the applicants are aware of two other Swedish companies working with the concept; Samster AB and Free Energy AB. In Switzerland, several large demonstration projects have been constructed in new, low-energy housing developments where the PVT collectors are used to pre-heat domestic hot water, provide heat to the heat pump, or recharge the boreholes (Good et al., 2015; Rommel et al., 2015). They are also used in an advanced “low-exergy” housing concept that is driving new, high efficiency heat pump development (Baetschmann and Leibundgut, 2012; Meggers et al., 2012).

Solar sourced heat pumps, where solar thermal collectors are the only heat exchangers on the source side, have been on the market for a number of years with limited success (Hadorn, 2015), but only recently have PVT collectors been considered. This is in part due to the recent cost reduction and popularity of PV modules that now make PVT collectors more interesting economically. During the winter of 2018, a PVT-sourced heat pump test system at Fraunhofer-ISE successfully provided peak heating and domestic hot water loads for a simulated single-family house during a clear night reaching -10 °C (Schmidt et al., 2018). Frost formation was also much less than a typical air heat exchanger due to the reduced air mass passing over the collector. The PVT collectors in the test had insulation on the rear, and if it were removed the authors estimated that evaporator inlet temperatures would increase by 10K, highlighting the potential for improvement.

Research into heat pump controls are increasingly influenced by solar PV. Storage is usually relatively expensive, therefore utilizing existing components in the system such as the hot water tank (Fischer et al., 2015, 2014)or boreholes (Hirvonen et al., 2018)can be more effective than batteries or selling to the grid. This project aims to further improve on previous work by developing a smart and adaptive systems control towards the maximization of PV electricity utilization and economic value for the building owner.

References

Baetschmann, M., Leibundgut, H., 2012. LowEx Solar Building System: Integration of PV/T Collectors into Low Exergy Building Systems. Energy Procedia 30, 1052–1059. https://doi.org/10.1016/j.egypro.2012.11.118

Benson, J., Ollas, P., Räftegård, O., Gervind, P., 2018. Solhybrid och bergvärme – Optimering av systemprestanda (2018:03).

Bombarda, P., Di Marcoberardino, G., Lucchini, A., Leva, S., Manzolini, G., Molinaroli, L., Pedranzini, F., Simonetti, R., 2016. Thermal and electric performances of roll-bond flat plate applied to conventional PV modules for heat recovery. Appl. Therm. Eng. 105, 304–313. https://doi.org/10.1016/j.applthermaleng.2016.05.172

Brahim, T., Jemni, A., 2017. Economical assessment and applications of photovoltaic/thermal hybrid solar technology: A review. Sol. Energy 153, 540–561. https://doi.org/10.1016/j.solener.2017.05.081

Energiföretagen, 2018. Fjärrvärmens Lokal Miljövärden 2017.

Energimyndigheten (Swedish Energy Agency), 2019. Energiläget (Energy in Sweden) - ET 2019:3.

Fischer, D., Rautenberg, F., Wirtz, T., Wille-Haussmann, B., Madani, H., 2015. Smart Meter Enabled Control for Variable Speed Heat Pumps to Increase PV Self-Consumption. 24th IIR Int. Congr. Refrig. ID:580. https://doi.org/10.13140/RG.2.1.2566.3762

Fischer, D., Toral, T.R., Lindberg, K.B., Wille-Haussmann, B., Madani, H., 2014. Investigation of Thermal Storage Operation Strategies with Heat Pumps in German Multi Family Houses. Energy Procedia 58, 137–144. https://doi.org/10.1016/j.egypro.2014.10.420

Gervind, P., Benson, J., Jardeby, Å., Nordman, R., 2016. Solhybrid och bergvärme- Förnybart med ny systemlösning (2016:01).

Good, C., Chen, J., Dai, Y., Hestnes, A.G., 2015. Hybrid Photovoltaic-thermal Systems in Buildings – A Review. Energy Procedia 70, 683–690. https://doi.org/10.1016/j.egypro.2015.02.176

Hadorn, J.-C. (Editor), 2015. Solar and Heat Pump Systems for Residential Buildings, First. ed. Ernst & Sohn GmbH & Co., Berlin.

Hirvonen, J., ur Rehman, H., Sirén, K., 2018. Techno-economic optimization and analysis of a high latitude solar district heating system with seasonal storage, considering different community sizes. Sol. Energy 162, 472–488. https://doi.org/10.1016/j.solener.2018.01.052

Johansson, M., 2018. Mistra Innovation - Solhybrid Resultat [WWW Document]. URL http://www.mistrainnovation.se/download/18.1533c93215be4b634bc213e/1527530779381/SunHybrid - Resultat -MJLF.pdf (accessed 2.7.19).

Jordan, D.C., Kurtz, S.R., 2013. Photovoltaic Degradation Rates — an Analytical Review. Prog. Photovoltaics Res. Appl. 21, 12–29. https://doi.org/10.1002/pip

Kamel, R.S., Fung, A.S., Dash, P.R.H., 2015. Solar systems and their integration with heat pumps: A review. Energy Build. 87, 395–412. https://doi.org/10.1016/j.enbuild.2014.11.030

Lindahl, J., Stoltz, C., Oller-Westerberg, A., Berard, J., 2019. National Survey Report of PV Power Applications in Sweden 2018.

Meggers, F., Ritter, V., Goffin, P., Baetschmann, M., Leibundgut, H., 2012. Low exergy building systems implementation. Energy 41, 48–55. https://doi.org/10.1016/j.energy.2011.07.031

Moro, A., Lonza, L., 2018. Electricity carbon intensity in European Member States: Impacts on GHG emissions of electric vehicles. Transp. Res. Part D Transp. Environ. 64, 5–14. https://doi.org/10.1016/j.trd.2017.07.012

Poppi, S., Sommerfeldt, N., Bales, C., Madani, H., Lundqvist, P., 2018. Techno-economic review of solar heat pump systems for residential heating applications. Renew. Sustain. Energy Rev. 81, 22–32. https://doi.org/10.1016/j.rser.2017.07.041

Rommel, M., Zenhäusern, D., Baggenstos, A., Türk, O., Brunold, S., 2015. Development of Glazed and Unglazed PVT Collectors and First Results of their Application in Different Projects. Energy Procedia 70, 318–323. https://doi.org/10.1016/j.egypro.2015.02.129

Schmidt, C., Schäfer, A., Kramer, K., 2018. Single source “solar thermal” heat pump for residential heat supply: Performance with an array of unglazed PVT collectors, in: 12th ISES Eurosun Conference. Rapperswil, Switzerland.

Sommerfeldt, N., Madani, H., 2019. In-depth techno-economic analysis of PV/Thermal plus ground source heat pump systems for multi-family houses in a heating dominated climate. Sol. Energy 190, 44–62. https://doi.org/10.1016/J.SOLENER.2019.07.080

Sommerfeldt, N., Madani, H., 2018. Ground Source Heat Pumps for Swedish Multi-Family Houses: Innovative co-generation and thermal storage strategies (Effsys Expand final report).

Sommerfeldt, N., Madani, H., 2016. Review of Solar PV/Thermal Plus Ground Source Heat Pump Systems for European Multi-Family Houses, in: 11th ISES Eurosun Conference. Palma de Mallorca, Spain, pp. 1360–1371. https://doi.org/10.18086/eurosun.2016.08.15

Swedish Energy Agency, 2015. Energy statistics for multi-dwelling buildings in 2014 (ES 2015:04). Eskilstuna.

Weiss, W., Spörk-Dür, M., 2018. Solar Heat Worldwide. IEA Solar Heating and Cooling Programme.

Zondag, H., 2008. Flat-plate PV-Thermal collectors and systems: A review. Renew. Sustain. Energy Rev. 12, 891–959. https://doi.org/10.1016/j.rser.2005.12.012

Zondag, H.A., van Helden, W.G.J., Bakker, M., Affolter, P., Eisenmann, W., Fechner, H., Rommel, M., Schapp, A., Sörensen, H., Tripanagnostopoulos, Y., 2005. PVT Roadmap: a European guide for the development and market introduction of PVT technology, in: 20th European Photovoltaci Solar Energy Confefrence. Barcelona.

Knowledge Gaps

Much has been learned about the performance of PVT collectors and the techno-economic potential of PVT+GSHP systems by the applicants over the past projects. The results have been consistent with other published studies, however there are some knowledge gaps that need to be filled to reach broader commercialization.

Component level

The PVT+GSHP concept is relatively undeveloped and thus has had little design dedicated to PVT collectors as part of a heat pump system. For example, making the heat exchanger with the roll-bond technique is known to improve efficiency due to its greater surface area contact with the PV module but at a higher cost. When the gains come from both sides, the PV and the surrounding air, the cost-benefit balance could change, therefore a comprehensive techno-economic analysis is needed to identify the benefits of the current design to roll-bond or extrusion alternatives. The low operating temperatures afforded by heat pump integration also make polymers a more viable material choice, which needs to be considered in the design and analysis.

From a pragmatic standpoint, supply chain and business model issues surrounding PVT production also require further investigation. This is in part connected to manufacturing techniques and in-house capabilities, but also certifications (e.g. Solar Keymark or IEC) which are challenging for PVT producers due to the combined electrical and thermal components. Prior to scaling production, an investigation into supply chain management, heat pump system packaging, and business models should be assessed.

Systems level

Previous systems modeling by the applicants has identified large, mainly residential, properties as the ideal initial customer for new PVT+GSHP systems. There is an opportunity for PVT to reduce the land required for GSHP boreholes, however there have not been any pilot installations to demonstrate the concept. Proving this potential in a real system is critical to market acceptance. From a research standpoint, a pilot system with a reduced borehole field would permit the quantitative validation of a complete systems model would have high scientific value.

There is also room for further development and optimization of the PVT heat pump concept. Advance control strategies for maximized utilization of solar energy are missing from the previous project, as are alternative building applications and system configurations. For example, there is a large market potential in Swedish villas that are now ready to replace their first (or second) heat pump. With shorter, degraded boreholes, a new, high efficiency heat pump will underperform and PVT could be a cost-effective, low-impact alternative to additional drilling. This is a unique problem to the Swedish market, and the authors are unaware of any prior research that addresses it.

Furthermore, the expansion of solar PV and heat pumps across Europe signal an export opportunity. The PVT+GSHP concept simulated for Sweden should be tested in other geographical locations, but also alternative PVT heat pump configurations. For example, GSHP systems are less common in the milder climates of central Europe where ASHP have an economic advantage. The disadvantage of a noisy air heat exchanger remains however, and using PVT as a solar/air heat exchanger would be quieter and less intrusive. To the applicant’s knowledge, the work at Fraunhofer ISE is the only study that quantified the potential and those studies only examined peak capacity. A full systems analysis has yet to be performed, but would be valuable to quantify the techno-economic potential for this concept in Sweden and Europe.

Objectives

The overall objective of this project is to advance the development of an integrated heating, cooling and electricity system solution for European buildings using solar PVT technology and heat pumps. This systems solution aims to reduce cost and improved technical performance towards the increased share of renewables in buildings and thus a more sustainable society.

At a component level, the goal is to develop a PVT module specifically for heat pump integration that improves thermal efficiency while reducing production cost. The process will be holistic in that the final design will need to balance not only performance and cost, but also pragmatic issues around manufacturing and durability. By the end of the project, the aim is to have a digitally optimized and physically prototyped PVT product that is ready for the market.

At a systems level, the goal is to validate and optimize the PVT heat pump concept in an expanded range of applications. Validating includes the successful deployment of a pilot system which confirms the benefits of a reduced borehole field. Optimization includes integration of the new PVT design and apply smart control strategies. The project also aims to demonstrate the techno-economic potential in a wider variety of building types, system configurations, geographical locations, and export markets.

At a business level, the goal is to create the necessary business models for deploying PVT collectors and PVT heat pump systems considering supply chains, component certification, systems integration and installer qualifications. The disparate components and stakeholders in a PVT heat pump system require a clear pathway from pilots and prototypes to commercial scale and export.

Partners

Developing PVT heat pumps requires input from each aspect of the system’s design and installation, with a broad and objective overview, and this project brings the necessary partners together. Research partner, KTH Energy Technology, has extensive experience in techno-economic analysis of complex systems, including solar PV and PVT collectors, heat pumps, and buildings. Previous studies are appended to this application, which have been published in leading scientific journals. The industrial partners are SMEs dedicated to the PVT+GSHP concept and its future potential in Sweden and abroad.

• Solhybrid i Småland AB(Project Leader) is a solar energy provider developing a PVT collector specifically for hybrid heat pumps. A second generation product manufactured in partnership with Lenhovda Radiatorfabrik is ready for the market and the research in this project would help to further develop the technology towards improving performance and reducing manufacturing costs.
• MegaWatt Solutions Nordic AB(within BrainHeart Energy AB) is developing a modular and scalable GSHP system solution, constructed in a Swedish factory, specifically designed for large properties. A PVT hybrid heat pump helps increase borehole life circle and performance, increase Heat Pump performance, reduce installation time and operational electricity cost. Critical aspects of their goals towards renovating existing buildings for sustainability as quickly as possible.
• Bengt Dahlgren Stockholm Geo ABis a progressive engineering consultancy with expertise in ground thermal modeling and is looking to incorporate PVT into their GSHP projects. This project will help them develop that expertise and further expand the PVT+GSHP concept into the marketplace.

Methodology

Accomplishing the project’s objectives can be broken down into a matrix based on the need for digital prototyping (modeling/simulation) and empirical testing (prototype/experiment) at the component (PVT collector) and system (PVT heat pump) levels. This matrix is visualized in Figure 3, where the main work packages are mapped and interconnected, including a work package for business model development that incorporates the lessons learned from all of the other work packages. Additional work packages are defined for administrative and communication tasks.

Figure 3– Work package structure towards meeting project objectives

WP1: Project management

. KTH is the primary responsible with support from MegaWatt Solutions Nordic, Solhybrid, and Begnt Dahlgren Stockholm Geoenergy.

Management from Solhybrid and KTH will ensure that the work packages are executed successfully and the project’s objectives met, with adaption to unforeseen circumstances. Regular project meetings will be held with all partners together to review and maintain progress. The project will be administered by Solhybrid i Småland CEO Magnus Johansson, with research management led by Associate Professor Hatef Madani and post-doctoral researcher Nelson Sommerfeldt at the Applied Thermodynamics and Refrigeration division of KTH Energy Technology (all CVs attached). Research will be carried out by a new PhD student and the project will be the basis for their doctoral thesis.

WP2: PVT collector optimization

Advanced modeling techniques will be used to develop digital PVT collector prototypes towards improved design, material selection, and manufacturability. A novel design that increases surface area contact between the working fluid, PV module, and air will be modeled using CFD to identify optimal flow distribution patterns and heat flux potential. The influence of materials (i.e. metals versus polymers) on heat transfer will be tested with considerations for manufacturing technique and cost-effectiveness. The goal of this work package is to deliver a techno-economically optimized PVT solution for scalable production. KTH is the primary responsible for this work package, with support from Solhybrid and their manufacturing partner, Lenhovda Radiatorfabrik.

WP3: Physical PVT prototyping and testing

A physical prototype based on the most promising digital prototype design(s) will be constructed and tested under outdoor laboratory conditions at KTH. The laboratory tests will be used to confirm real world performance and validate the digital twin for use in systems simulation. Lessons learned from this work package, both in thermal performance and practical construction, will feed back into digital prototyping in an iterative development cycle. KTH is the primary responsible for this work package, with support from Solhybrid and their manufacturing partner, Lenhovda Radiatorfabrik.

WP4: Systems optimization through holistic and dynamic modeling

Building upon existing PVT+GSHP system models, the newly optimized PVT design from WP2/3 will be applied in holistic optimizations. The simulations, made in TRNSYS, are dynamic and include all components in the system, including heating and electrical demands from multiple buildings, heating distribution system with parasitic losses, and component interactions between the PVT, boreholes, and brine-to-water heat pump. The system solution will be evaluated under a variety of design and environmental conditions, including component sizing, building load conditions, and geographic locations with high export potential. In particular focus are smart control strategies which maximize the solar energy utilization and economic performance. In summary, this work package seeks to deliver techno-economically optimized system solutions for PVT integrated heat pumps for Swedish and European markets. KTH is the primary responsible with support from MWS, Solhybrid, and BD Stockholm Geo.

WP5: Pilot installation and validation

This work package is dedicated to the design, installation, and monitoring of a pilot PVT+GSHP system based on the concept developed during the previous Effsys Expand project. This system will be unique in that it will have a variable size borehole field that can validate the conclusions from previous research but still be converted to a full sized system if needed, thereby reducing the risk for the building owner. Sonority is the primary responsible for the work package with the GSHP system being designed, manufactured, and installed by MegaWatt Solutions and the PVT collectors supplied by Solhybrid. Hundreds of sensors will be installed and monitored using a state-of-the-art SCADA system supplied by Sonority. This pilot will use the PVT collector design from the previous Mistra project but includes the opportunity to replace the panels by the new panels developed under the current project. KTH will support the design and monitoring efforts from a research perspective, and after at least one year of operation utilize the data to validate a complete PVT+GSHP systems model.

WP6: Business model development

Business model innovation has been a driving force for sustainable product adoption around the world. This work package focuses on development of innovative business models in order to enhance the mass commercialization of the integrated energy solution provided by PVT heat pumps. The key elements of the business model canvas such as cost and revenue structure, the key activities, key resources, key partners, channels, etc. are analyzed; the barriers for the market penetration will be investigated. The final goal of this work package is to devise a roadmap for the commercialization of the product from the perspective of the SMEs involved in the project.

WP7: Strategies for communication and dissemination

There are three distinct target groups for this project; customers, suppliers, and researchers. To increase communications impact on the benefits of PVT heat pumps, a semi-customizable systems tool will be developed based on KTH systems models. KTH will work together with Sonority to develop the tool. Research results will be regularly published in national magazines, international conferences, and leading scientific journals. This project will also result in the publication of a Phd thesis. The timing of publications during the project will be coordinated with any patentable intellectual property accordingly. Both the tool and research results will be presented at industry events, and a public workshop will be held for actors outside the project to ask questions and provide external insights.

Expected Outcomes and Impact

In the social dimension, the results of this project can directly benefit large property owners by making renewable, low-carbon electric heating more accessible and affordable. This is the explicit goal of all the applicants who will combine their strengths from the academic and commercial perspectives towards installing more solar heat pump systems, with a mission of reducing the 670 kilotons of CO_2-eqemitted by MFH heating supply in Sweden and millions more in Europe. The project also promotes the seamless integration of solar energy into the building energy system, creating a new pathway towards increased renewable energy share. The communication tool to be developed in WP6 will be specifically dedicated to educating the public on these benefits, which we believe to be a critical aspect of increased adoption.

These goals can be achieved by building interest and trust amongst engineering and equipment installers across the industry. The PVT+GSHP system concept is still at an early development stage, and publishing results from successful pilot projects and validated simulations helps build acceptance and adoption. Additionally, successful development of the PVT collector and climate specific PVT heat pumps can lead to exporting the system concept to larger international markets, boosting domestic industry.

In the academic dimension, this project is a strategic part of KTH’s research portfolio in developing technologies to accelerate the electrification of the built environment. Interest in PVT from researchers is growing and KTH will be amongst the leading universities and institutions across Europe developing the concept. PVT has had difficulties expanding beyond pilot projects, however this project and its partners are uniquely qualified to break through.