This study conducts a detailed techno-economic analysis of photovoltaic-thermal (PVT) collectors integrated with ground-source heat pumps (GSHPs) for land-constrained multi-family buildings in cold climates. Using dynamic TRNSYS simulations, the system is designed around an undersized borehole field and incorporates realistic electricity pricing models, including dynamic spot prices and capacity-based tariffs, and peak demand considerations. A stepwise analysis evaluates five PVT absorber types, array sizes, layouts, and control strategies. The most cost-effective design combines 60 m² of unglazed finned collectors, pre-borehole layout, and 80 l/h-m² fixed flow, achieving a seasonal performance factor above 2.7 and a minimum total life-cycle cost (TLCC) of €451 k€. Among all design variables, array size has the greatest impact on system performance and cost, with flow rate being the next most critical factor. Relative to a stand-alone GSHP, the hybrid system lowers peak electric load by 10 % and reduces total life-cycle cost by 4–23 % when benchmarked against alternative heating configurations including district heating, air-source heat pump, and PV-assisted GSHP. Scenario analyses show that electricity pricing structure and volatility significantly influence optimal collector sizing, with higher electricity prices favoring larger PVT array sizes. The results provide actionable design guidelines for researchers and practitioners seeking to improve performance and cost-effectiveness of heat pump systems, and to support their broader deployment in space- and grid-constrained urban environments.

One of the most promising methods of decarbonizing the global building heating and cooling load is with solar photovoltaic (PV) powered heat pumps (HP). The complex nature of these systems and the interdependent interactions between each technology and the energy markets involve various sophisticated models to simulate accurately. This often leaves model descriptions lacking, particularly when qualitative discussion is required. This article reviews the models that exist and provides best practices for designing and simulating PV + HP systems of various complexities. The key performance indicators for electricity generation and total life cycle cost are summarized. This article then provides a detailed and comprehensive method for the techno-economic analysis of heat pumps powered with PV using an example of North American cold climates. For each component of the system, a model and boundary condition are described, and motivations are explained, as well as descriptions of alternatives and motivations for not using them. The result shows a method that combines five disparate models across multiple computer programs into a single analysis that produces critical metrics for technical, economic, and climate impact analysis. This paper identified the best practices for building energy demand and supply simulation with a particular focus on prosumer electrification via PV and HPs. This model is generalizable and the economic and policy implications of replacing fossil fuel heating with solar-powered heat pumps in both rural and urban areas that are discussed here, and future work is proposed to eliminate natural gas used for heating. High-leverage opportunities exist to enhance support for the development of free and open-source integrated systems modeling tools as well as open data to provide transparent trusted results to help guide policymakers and investors.

There has been an increase in solar photovoltaic/thermal (PVT) research in recent years, however, relatively little research has been dedicated to the design of PVT collectors as part of a heat pump system. This study aims to identify cost-effective design strategies for a PVT collector absorber to be integrated into a ground source heat pump (GSHP) circuit and enhance heat capture from the ambient air. The effect of geometry, material selection, fins, and forced convection on the overall U-value and thermal performance coefficients of the collector, are evaluated under steady state conditions using numerical modelling tool COMSOL Multiphysics. An annual mean fluid temperature profile is derived from a PVT + GSHP system simulation to calculate the annual thermal energy output, energy-to-mass and energy-to-cost ratios of the absorbers. Results show that the addition of fins and forced convection have the greatest influence on collector thermal performance, while material selection has a negligible impact. The corrugated, polycarbonate absorber with 10 mm fins, generates 55 % more thermal energy (1,464 kWhth/m2-yr) than the reference metallic sheet and tube collector at an energy-to-cost ratio 1/10th the reference, suggesting good market potential. An exergy analysis reveals that thermal exergy contributes 20 % to 50 % of the total exergy output, highlighting that low-temperature PVT designs exhibiting a smaller thermal share relative to electrical exergy compared to their higher temperature counterparts. This work's novelty and contribution comes from PVT design specifically for GSHP integration, examined at component and system levels, from both technical and economic perspectives.

This study investigates the impact of cold climate weather patterns on the thermal performance of two novel designs of extruded photovoltaic thermal (PVT) collectors optimized for integration with low-temperature heat pumps. The study aims to provide a comprehensive understanding of how different weather conditions, including condensation, rainfall, frost formation, and snow, affect the thermal output of these systems. The study compares two PVT designs, one with fins attached to the thermal collector and another without, to determine the optimal configuration for maximizing efficiency under varying cold climate conditions. The results indicate significant differences in performance between the finned and non-finned designs, with the finned design showing up to 11% better thermal performance. A strong impact on the thermal performance of the PVT as a result of the different weather patterns was also observed, with up to 60% thermal gains from rainfall, and 21% thermal losses during defrosting. This research fills a critical gap in the understanding of PVT performance in cold climates and provides valuable insights that can be used to determine the appropriate control strategies for heat pumps to enhance system efficiency. The findings offer a valuable contribution to the development of more efficient renewable energy systems in regions with harsh winter conditions.

This study compares the thermal performance of two novel box-channel PVT collectors, assessing the impactof fins in low temperature operating conditions. This work will contribute the understanding of how PVTcollectors can be integrated with GSHPs for borehole regeneration in cold climates. The two prototype PVTcollectors were tested simultaneously at an outdoor testing facility in Stockholm, Sweden. The outdoor testingenvironment allows for the analysis of a variety of different weather conditions under different fluid flow ratesas well as different roof installations. It was found that the finned PVT collector displayed a potential annualthermal energy output 11% higher than that of the non-finned one at the optimal flow rate of 77 l/h m2. At theoptimal flow rate, fluctuations in wind speed also significantly impacted the observed specific thermal energyof the PVTs, mainly the finned PVT collector, with an increase of 93% being observed due to a 2.5 m/s increasein wind speed.

This study introduces a high-resolution, data-driven approach for optimizing district heating networks using source-load mapping, focusing on Stockholm as a case study. The methodology integrates detailed building energy performance data (2014–2022) with geographic data from the Swedish Survey Agency, employing advanced clustering techniques such as K-means Clustering, Agglomerative Clustering, DBSCAN, Spectral Clustering, and Gaussian Mixture Model (GMM) Clustering to identify optimal locations for distributed heat sources, including data centers, supermarkets, and water bodies. Quantitative results show that these environmentally friendly sources could supply 54 % of Stockholm's total annual heat demand of 7.7 TWh/year, equating to 4.2 TWh from residual heat sources. Data centers contribute 0.48 TWh, water bodies provide 3.4 TWh, and supermarkets contribute 0.3 TWh annually. Economic analysis further reveals that 98 % of residual heat sources are economically viable, with marginal costs of heat (MCOH) for data centers, supermarkets, and water bodies estimated at 12.7 EUR/MWh, 16.0 EUR/MWh, and 20.0 EUR/MWh, respectively—well below the Open District Heating (ODH) market price of 22.0 EUR/MWh. The policy implications of these findings are profound. Policymakers can leverage this methodology to identify economically viable heat sources, enabling the creation of regulations that incentivize the integration of distributed heat sources into existing district heating networks. This can lead to reduced energy costs, enhanced sustainability, and more resilient energy systems. Practically, urban planners and energy utilities can use clustering insights to optimize the placement of new infrastructure, such as data centers, ensuring they are strategically located in high-demand zones. Furthermore, the study's methodology can be replicated in other urban contexts, offering cities worldwide a scalable tool for improving the efficiency and sustainability of their heating networks. These findings support the transition to low-carbon energy solutions and provide actionable recommendations for the long-term development of urban energy systems.

This study assesses the performance of a PVT+GSHP system using four different PVT collectors, each withunique design features, for a multi-family building in Stockholm. Thermal performance coefficients areobtained through outdoor testing of each collector under low-temperature conditions, and incorporated into acomprehensive dynamic system model in TRNSYS. The study varies the design and array size of the PVTcollectors and evaluates their impact on the techno-economic performance of the system, consideringtraditional and undersized borehole fields. Technical performance metrics include annual thermal energyoutput, seasonal performance factor and back-up heater utilization, and economic performance is assessed withtotal life cycle cost (TLCC). The results show that when integrating PVTs with GSHP systems, lower collectorcosts should be prioritized over enhanced thermal performance. Despite the finned designs exhibiting a higherthermal yield (up to 10%) this only improves the seasonal performance factor by 0.6% compared to non-finneddesigns, but can increase TLCC by up to 5.2%

This study empirically investigates the optimal design features of photovoltaic-thermal (PVT) collectors for integration with ground source heat pump (GSHP) systems, considering technical and economic factors. Outdoor experiments are conducted in Stockholm, Sweden, comparing five unglazed and uninsulated PVT collector designs a) Reference Sheet & Tube b) Sheet & Tube with a narrow air gap between PV and absorber plate c) Box-channel polypropylene d) Finned tube and e) Box-channel aluminum with fins at operating temperatures below ambient. The findings indicate that the box-channel aluminum design with fins, characterized by a superior combination of high zero-loss efficiency and a high U-value, emerges as the ideal PVT design for integration with ground source heat pumps, taking into account both technical and economic considerations. Despite having a relative specific thermal cost 9% higher than the reference collector, this design demonstrates the capability to generate 2,096 kWh/(m2a) of thermal energy, marking an 83.3% increase compared to the reference, with a 136% higher energy-to-mass ratio.

This research raises the possibility for households in energy poverty to participate in shared photovoltaic systems in renewable energy communities (REC) to reduce their energy costs, with investment costs covered by public institutions. It begins by evaluating the current solution for vulnerable households, which relies on public subsidies to lower energy costs without addressing root causes or improving environmental impacts. The study compares traditional subsidies with REC participation for vulnerable households. By simulating a REC composed of such households, the results indicate that REC participation is more cost-effective for public institutions than energy subsidies. At the economically optimal size of 31 kWp, the cost of subsidies decreases by 58,000 €, a 50% reduction, with household savings increasing by 6%. At 58 kWp, the need for additional support checks is eliminated, increasing household savings by 65% but with a lower NPV of 22,500 €. The largest viable system, 75 kWp, increases average household savings by 82%. This approach also leads to a net reduction in GHG emissions, engaging previously excluded households in the energy transition.

Ground source heat pump (GSHP) systems offer a low carbon heating and cooling solution for the decarbonization of buildings. As global temperatures rise, the cooling requirements of buildings will grow, even in regions where cooling systems have been historically uncommon due to their colder climate, such as Sweden. The combination of free cooling (FC) with GSHPs seems like a natural way to meet the increasing cooling needs, since the heat extracted from the building during the summer months can be injected into the ground to potentially regenerate the borehole field and enhance heat pump performance. However, a technology that is generally integrated with GSHP systems for borehole regeneration are photovoltaic/thermal collectors. This study investigates the performance of a ground source heat pump system with free cooling for a multi-family building in Stockholm, Sweden, and the interference on the free cooling capabilities of the system when photovoltaic/thermal collectors are present. The results demonstrate that the integration of PVT and FC not only maintains the cooling supply but also enhances heat pump performance, all the while reducing borehole length and land area requirements.