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 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.

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.

Heat pumps and water tanks can be used to increase PV self-consumption in buildings without any additional equipment, but there is sometimes a lack of economic incentives to maximize it that limits economic gains. Therefore, pricing conditions need to change in order to make self-consumption strategies more interesting for prosumers. This study aims at determining what, if any, unsubsidized market conditions could lead to economically motivated self-consumption control strategies with solar heat pumps. A sensitivity analysis is used on multiple pricing models based on current market conditions for a solar PV and ground source heat pump system for a single-family house in Norrköping, Sweden. The results show that control strategies aimed at maximizing self-consumption have very little impact on net costs, regardless of pricing model or variation in price. Feed-in-bonus is the most important aspect when comparing different pricing schemes, and no other sensitivity comes close.

Within the heat pump sector, there are applications where photovoltaic/thermal (PVT) collectors can offer greater value with lower investment costs than the current alternatives. The first is ground source heat pumps (GSHP) with under dimensioned boreholes. The second is a solar source heat pump (SSHP) where the PVT collectors are a replacement for the traditional air heat exchanger in an air source heat pump (ASHP). Complete systems models for a multi-family house are simulated in TRNSYS to determine seasonal performance factors (SPF), which are then compared technically and economically to each respective alternative. A 156 m(2) PVT array is capable of improving the SPF of a degraded GSHP by 30%, the same gains as drilling additional boreholes but at a lower cost. The SSHP with a 235 m(2) PVT array can reach an SPF of 2.6, comparable to the performance of an ASHP, but has the cost of a GSHP. Already today, PVT can economically compete with borehole drilling for GSHP and the SSHP concept shows enough market potential to warrant investment and development towards broader adoption.

In order to improve the life quality of its inhabitants, show the world Japan's commitment to protect the environment, and position itself as a game changer in the global energy sector, what would be a better place where to start from than Minato City, in order to make it Japan’s Green Window to the World.

Four different Key Performance Indicators (KPIs) are used to quantify the accomplishment of the objective of making Minato sustainable by 2040. Based on a qualitative system model for Minato, quantitative models were developed using both HOMER Pro® and the Long-range Energy Alternatives Planning System (LEAP). For these models, three different scenarios are used: one representing a business as usual scenario, another showing what the future would look like if all the existing policies and goals were to be met, and the last one depicting what necessary improvements and investments should be made to achieve a sustainable Minato by 2040. A technical and economic analysis of the results of the models was made, resulting in what is thought to be the best proposal for Minato.

The proposal consists in the installation of 3 195 MW of onshore wind power and 456 MW of solar PV, both to be constructed in three phases. From the 16 364,2 MW of expected necessary installed capacity in Minato for 2040, 61,1% will come from the grid, 19,5% from the wind turbines, 2,8% from solar PV, 11,1% from stored energy in batteries, 5,4% from Hydrogen, and the remaining 0,1% from the already existing incineration plant. The overall proposition has a NPV of ¥ 2,64 Trillion, and decreases emissions in Minato to 1,0 million tonnes of CO2. The final system has an efficiency of 70,5% and a renewable energy fraction of 59,1%. Even though the KPIs goals are not met with this proposal, a large part of the road is covered towards a sustainable city. The renewable energy fraction increases from 9,5% to 59,1%, the total primary energy supply (per year perperson) and the CO2 emissions are reduced by 66% and 86% respectively, and the crowdedness factor is brought down from 173% to 150%, all with regards to base year 2015. If compared to the goals set by the Japanese Government for 2030, (22-24% renewables in primary energy matrix, 26% emissions reduction and 24% self-sufficiency ratio) it can be seen that the values obtained for the Nokko scenario would largely exceed them.