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Sommerfeldt, Nelson, PhDORCID iD iconorcid.org/0000-0002-2603-7595
Publications (10 of 30) Show all publications
Pourier, C., Beltran, F. & Sommerfeldt, N. (2024). Solar photovoltaic/thermal (PVT) technology collectors and free cooling in ground source heat pump systems. Solar Energy Advances, 4, Article ID 100050.
Open this publication in new window or tab >>Solar photovoltaic/thermal (PVT) technology collectors and free cooling in ground source heat pump systems
2024 (English)In: Solar Energy Advances, E-ISSN 2667-1131, Vol. 4, article id 100050Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Heat pumps, Low energy buildings, Passive cooling, Solar hybrid, Solar PVT
National Category
Energy Engineering Building Technologies
Identifiers
urn:nbn:se:kth:diva-343193 (URN)10.1016/j.seja.2023.100050 (DOI)2-s2.0-85183573613 (Scopus ID)
Note

QC 20240209

Available from: 2024-02-08 Created: 2024-02-08 Last updated: 2024-02-09Bibliographically approved
Sommerfeldt, N. & Pearce, J. M. (2023). Can grid-tied solar photovoltaics lead to residential heating electrification?: A techno-economic case study in the midwestern US. Applied Energy, 336, Article ID 120838.
Open this publication in new window or tab >>Can grid-tied solar photovoltaics lead to residential heating electrification?: A techno-economic case study in the midwestern US
2023 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 336, article id 120838Article in journal (Refereed) Published
Abstract [en]

This study aims to quantify the techno-economic potential of using solar photovoltaics (PV) to support heat pumps (HP) towards the replacement of natural gas heating in a representative North American residence from a house owner's point of view. For this purpose, simulations are performed on: (1) a residential natural gas-based heating system and grid electricity, (2) a residential natural gas-based heating system with PV to serve the electric load, (3) a residential HP system with grid electricity, and (4) a residential HP+PV system. Detailed descriptions are provided along with a comprehensive sensitivity analysis for identifying specific boundary conditions that enable lower total life cycle cost. The results show that under typical inflation conditions, the lifecycle cost of natural gas and reversable, air-source heat pumps are nearly identical, however the electricity rate structure makes PV costlier. With higher rates of inflation or lower PV capital costs, PV becomes a hedge against rising prices and encourages the adoption of HPs by also locking in both electricity and heating cost growth. The real internal rate of return for such prosumer technologies is 20x greater than a long-term certificate of deposit, which demonstrates the additional value PV and HP technologies offer prosumers over comparably secure investment vehicles while making substantive reductions in carbon emissions. Using the large volume of results generated, impacts on energy policy are discussed, including rebates, net-metering, and utility business models.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Photovoltaic, Solar energy, Heat pump, Electrification, Residential heating, Energy policy
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-325239 (URN)10.1016/j.apenergy.2023.120838 (DOI)000944389600001 ()2-s2.0-85148363295 (Scopus ID)
Note

QC 20230404

Available from: 2023-04-04 Created: 2023-04-04 Last updated: 2023-04-04Bibliographically approved
Adesanya, A. A., Sommerfeldt, N. & Pearce, J. M. (2022). Achieving 100% Renewable and Self-Sufficient Electricity in Impoverished, Rural, Northern Climates: Case Studies from Upper Michigan, USA. Electricity, 3(3), 264-296
Open this publication in new window or tab >>Achieving 100% Renewable and Self-Sufficient Electricity in Impoverished, Rural, Northern Climates: Case Studies from Upper Michigan, USA
2022 (English)In: Electricity, E-ISSN 2673-4826, Vol. 3, no 3, p. 264-296Article, review/survey (Refereed) Published
Abstract [en]

The development of 100% renewable electricity (RE) systems play a pivotal role in ensuring climate stability. Many municipalities blessed with wealth, an educated and progressive citizenry, and large RE resources, have already reached 100% RE generation. Impoverished municipalities in unwelcoming environments both politically and climatically (e.g., northern latitudes with long, dark winter conditions) appear to be incapable of transitioning to renewables. This study challenges that widespread assumption by conducting a detailed technical and economic analysis for three representative municipalities in the Western Upper Peninsula of Michigan. Each municipality is simulated with their own hourly electricity demand and climate profiles using an electrical supply system based on local wind, solar, hydropower, and battery storage. Sensitivities are run on all economic and technical variables. Results show that transition to 100% RE is technically feasible and economically viable. In all baseline scenarios, the 100% RE systems produced a levelized cost of electricity up to 43% less than the centralized utility rates, which are predominantly fueled by gas and coal. Current policies, however, prevent such self-sufficient systems from being deployed, which are not only detrimental to the global environment, but also aggravate the economic depression of such regions. Potential energy savings advance the prohibitive energy justice principle.

Place, publisher, year, edition, pages
MDPI AG, 2022
Keywords
just transition, municipalities, renewable electricity, rural northern climate, self-sufficient
National Category
Energy Engineering Energy Systems
Identifiers
urn:nbn:se:kth:diva-335675 (URN)10.3390/electricity3030016 (DOI)2-s2.0-85159596227 (Scopus ID)
Note

QC 20230908

Available from: 2023-09-08 Created: 2023-09-08 Last updated: 2023-09-08Bibliographically approved
Sommerfeldt, N., Lemoine, I. & Madani Larijani, H. (2022). Hide and seek: The supply and demand of information for household solar photovoltaic investment. Energy Policy, 161, 112726, Article ID 112726.
Open this publication in new window or tab >>Hide and seek: The supply and demand of information for household solar photovoltaic investment
2022 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 161, p. 112726-, article id 112726Article in journal (Refereed) Published
Abstract [en]

Buildings provide an ideal platform for solar photovoltaics (PV) towards sustainable development goals, and the decision to invest in PV lies predominantly with building owners. Information delivery is critical for the diffusion of innovations, and this study aims to improve the quality of information for household PV investors in Sweden. A User Journey Mapping approach is applied with a combination of semi-structured interviews and a review of online solar calculators. The results show that despite a rapid growth in the quantity of information there is still a gap between demand and supply due to the lack of clarity and trustworthiness of information. This is clearly demonstrated in the review of online calculators, which show a high variance in results. Payback time, for example, ranged from 7 to 18 years for a single test case. The information gap can be closed by creating neutral, non-commercial online information sources that focus on transparency and education where household investors can validate supplier offers and analyses. The PV industry risks eroding trust in the market, which will likely slow adoption by the early majority and hinder sustainability goals.

Place, publisher, year, edition, pages
Elsevier BV, 2022
Keywords
PV, Prosumers, Techno-economic analysis, Investment behavior, Information asymmetry
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-309302 (URN)10.1016/j.enpol.2021.112726 (DOI)000745980300004 ()2-s2.0-85119910108 (Scopus ID)
Note

QC 20220301

Available from: 2022-03-01 Created: 2022-03-01 Last updated: 2022-06-25Bibliographically approved
Tóth, M. & Sommerfeldt, N. (2022). PV self-consumption prediction methods using supervised machine learning. In: 2022 BuildSim Nordic, BSN 2022: . Paper presented at 2022 BuildSim Nordic, BSN 2022, Copenhagen, Denmark, Aug 22 2022 - Aug 23 2022. EDP Sciences, Article ID 02003.
Open this publication in new window or tab >>PV self-consumption prediction methods using supervised machine learning
2022 (English)In: 2022 BuildSim Nordic, BSN 2022, EDP Sciences , 2022, article id 02003Conference paper, Published paper (Refereed)
Abstract [en]

The increased prevalence of photovoltaic (PV) self-consumption policies across Europe and the world place an increased importance on accurate predictions for life-cycle costing during the planning phase. This study presents several machine learning and regression models for predicting self-consumption, trained on a variety of datasets from Sweden. The results show that advanced ML models have an improved performance over simpler regressions, where the highest performing model, Random Forest, has a mean average error of 1.5 percentage points and an R2 of 0.977. Training models using widely available typical meteorological year (TMY) climate data is also shown to introduce small, acceptable errors when tested against spatially and temporally matched climate and load data. The ability to train the ML models with TMY climate data makes their adoption easier and builds on previous work by demonstrating the robustness of the methodology as a self-consumption prediction tool. The low error and high R2 are a notable improvement over previous estimation models and the minimal input data requirements make them easy to adopt and apply in a wide array of applications.

Place, publisher, year, edition, pages
EDP Sciences, 2022
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-333443 (URN)10.1051/e3sconf/202236202003 (DOI)2-s2.0-85146889141 (Scopus ID)
Conference
2022 BuildSim Nordic, BSN 2022, Copenhagen, Denmark, Aug 22 2022 - Aug 23 2022
Note

QC 20230802

Available from: 2023-08-02 Created: 2023-08-02 Last updated: 2023-08-02Bibliographically approved
Beltran, F., Sommerfeldt, N., Padovani, F., Rolando, D. & Madani Larijani, H. (2022). Solar Heat Pumps and Self-Consumption Can (and should) electricity suppliers encourage thermal storage?. In: 2022 BuildSim Nordic, BSN 2022: . Paper presented at 2022 BuildSim Nordic, BSN 2022, Copenhagen, Denmark, Aug 22 2022 - Aug 23 2022. EDP Sciences, Article ID 06005.
Open this publication in new window or tab >>Solar Heat Pumps and Self-Consumption Can (and should) electricity suppliers encourage thermal storage?
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2022 (English)In: 2022 BuildSim Nordic, BSN 2022, EDP Sciences , 2022, article id 06005Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
EDP Sciences, 2022
National Category
Energy Systems
Identifiers
urn:nbn:se:kth:diva-333444 (URN)10.1051/e3sconf/202236206005 (DOI)2-s2.0-85146893366 (Scopus ID)
Conference
2022 BuildSim Nordic, BSN 2022, Copenhagen, Denmark, Aug 22 2022 - Aug 23 2022
Note

QC 20230802

Available from: 2023-08-02 Created: 2023-08-02 Last updated: 2023-08-02Bibliographically approved
Sommerfeldt, N., Lemoine, I. & Madani Larijani, H. (2021). A User-Centered Design Approach to Identify Behavioral Biases in the Adoption of Solar PV by Households. In: Xianli Zhu and Gabriela Prata Dias (Ed.), 6th European Conference on Behaviour Change for Energy Efficiency: . Paper presented at BEHAVE 2020‑2021 (pp. 134-137). Copenhagen
Open this publication in new window or tab >>A User-Centered Design Approach to Identify Behavioral Biases in the Adoption of Solar PV by Households
2021 (English)In: 6th European Conference on Behaviour Change for Energy Efficiency / [ed] Xianli Zhu and Gabriela Prata Dias, Copenhagen, 2021, p. 134-137Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Copenhagen: , 2021
Keywords
diffusion, communication, design thinking, user-centered design, cognitive biases
National Category
Energy Engineering Media and Communications
Research subject
Energy Technology; Media Technology
Identifiers
urn:nbn:se:kth:diva-294258 (URN)
Conference
BEHAVE 2020‑2021
Funder
Swedish Energy Agency
Note

Part of proceedings: ISBN 9788794094016, QC 20230117

Available from: 2021-05-12 Created: 2021-05-12 Last updated: 2024-03-18Bibliographically approved
Padovani, F., Sommerfeldt, N., Longobardi, F. & Pearce, J. M. (2021). Decarbonizing rural residential buildings in cold climates: A techno-economic analysis of heating electrification. Energy and Buildings, 250, Article ID 111284.
Open this publication in new window or tab >>Decarbonizing rural residential buildings in cold climates: A techno-economic analysis of heating electrification
2021 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 250, article id 111284Article in journal (Refereed) Published
Abstract [en]

Given the need for decarbonization of the heating sector and the acute need of a propane replacement in the U.S. Upper Midwest, this study quantifies the techno-economic characteristics of sustainable heating electrification in isolated rural, residential buildings in cold climates without natural gas supply. Archetypal buildings are modeled under four levels of electrification. At each electrification level, a parametric solar photovoltaic (PV) sizing analysis is performed and the total life cycle cost, renewable fraction and greenhouse gas (GHG) emissions are calculated based on the primary energy supply for each building type. Cost optimal solutions are stress-tested with multi-dimensional sensitivity analyses. The results show that the total life cycle cost favors heating electrification in all cases and combining PV with heat pumps can reduce residential building GHG emissions by up to 50% immediately. This effect will grow over time, with over 90% reduction of building emissions if renewable energy targets are met. In using primary energy and emissions along with the multi-dimensional sensitivities, this study unique demonstrates the complex techno-economic interactions of PV and heat pumps. It is concluded that electrification is an economically viable decarbonization method for cold climates both now and in the future.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2021
Keywords
Electrification, Photovoltaic, Heat pump, Solar heat pump, Decarbonization, Electrify everything
National Category
Energy Engineering Energy Systems
Identifiers
urn:nbn:se:kth:diva-302637 (URN)10.1016/j.enbuild.2021.111284 (DOI)000693461300004 ()2-s2.0-85111848656 (Scopus ID)
Note

QC 20211004

Available from: 2021-10-04 Created: 2021-10-04 Last updated: 2024-03-18Bibliographically approved
Pearce, J. M. & Sommerfeldt, N. (2021). Economics of Grid-Tied Solar Photovoltaic Systems Coupled to Heat Pumps: The Case of Northern Climates of the US and Canada. Energies, 14(4), Article ID 834.
Open this publication in new window or tab >>Economics of Grid-Tied Solar Photovoltaic Systems Coupled to Heat Pumps: The Case of Northern Climates of the US and Canada
2021 (English)In: Energies, E-ISSN 1996-1073, Vol. 14, no 4, article id 834Article in journal (Refereed) Published
Abstract [en]

Solar photovoltaic (PV) technology is now a profitable method to decarbonize the grid, but if catastrophic climate change is to be avoided, emissions from transportation and heating must also decarbonize. One approach to renewable heating is leveraging improvements in PV with heat pumps (HPs). To determine the potential for PV+HP systems in northern areas of North America, this study performs numerical simulations and economic analysis using the same loads and climate, but with local electricity and natural gas rates for Sault Ste. Marie, in both Canada and U.S. Ground-mounted, fixed-tilt, grid-tied PV systems are sized to match 100% of electric loads considering cases both with and without air source HPs for residences with natural gas-based heating. For the first time the results show North American residents can profitably install residential PV+HP systems, earning up to 1.9% return in the U.S. and 2.7% in Canada, to provide for all of their electric and heating needs. Returns on PV-only systems are higher, up to 4.3%; however, the PV capacities are less than half. These results suggest northern homeowners have a clear and simple method to reduce their greenhouse gas emissions by making an investment that offers a higher internal rate of return than savings accounts, CDs and GICs in both countries. Residential PV and solar-powered heat pumps can be considered 25-year investments in financial security and environmental sustainability.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
photovoltaic, heat pumps, electrification, solar energy, renewable energy, northern climate, solar-assisted heat pumps, sustainable energy, net zero, greenhouse gas emissions
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-292282 (URN)10.3390/en14040834 (DOI)000623461000001 ()2-s2.0-85106448085 (Scopus ID)
Note

QC 20210331

Available from: 2021-03-31 Created: 2021-03-31 Last updated: 2023-08-28Bibliographically approved
Schreurs, T., Madani Larijani, H., Zottl, A., Sommerfeldt, N. & Zucker, G. (2021). Techno-economic analysis of combined heat pump and solar PV system for multi-family houses: An Austrian case study. Energy Strategy Reviews, 36, Article ID 100666.
Open this publication in new window or tab >>Techno-economic analysis of combined heat pump and solar PV system for multi-family houses: An Austrian case study
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2021 (English)In: Energy Strategy Reviews, ISSN 2211-467X, E-ISSN 2211-4688, Vol. 36, article id 100666Article in journal (Refereed) Published
Abstract [en]

With the increasing amount of building renovations in Austria, the potential increases for replacing conventional national gas heating systems with heat pumps (HP) and thereby reduce CO2 emissions particularly when combined with solar photovoltaics (PV). The Austrian subsidization scheme for HP and PV systems are different for every state, creating confusion and inconstancy for potential adopters. This study provides a parametric technoeconomic analysis of PV + HP systems to identify the critical economic parameters on profitability and make policy recommendations. A case study in Vienna is modelled using demand from the Building Model Generator and black box efficiency models for the HP and PV simulated with hourly time steps. The results show that both air-source and ground source heat pumps are currently profitable with PV under current subsidy schemes. The benefit-to-cost ratio (BCR) is highly influenced by capital costs and subsidies, however natural gas prices have the greatest influence. Increasing natural gas prices by 0.01 euro/kWh, or 17%, is enough to replace all other complicated subsidies for both HP and PV. This is equivalent to a carbon emissions price of 33 euro/ton and could result in a reduction of CO2 emissions in multi-family houses by approximately 45%-60%.

Place, publisher, year, edition, pages
Elsevier BV, 2021
Keywords
Solar energy, Heat pumps, Systems analysis, Sustainable subsidies
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-299695 (URN)10.1016/j.esr.2021.100666 (DOI)000678404500011 ()2-s2.0-85109458890 (Scopus ID)
Note

QC 20210818

Available from: 2021-08-18 Created: 2021-08-18 Last updated: 2022-06-25Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-2603-7595

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