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Tianqi Ruan

Decentralized PV systems in Sweden: Techno-economic analysis with a case study of Stockholm

📅 Date & Time: 15 May 2024, 09:30–13:00
📍 Location: Kollegiesalen, Brinellvägen 6, KTH Royal Institute of Technology

About the Thesis

Photovoltaic (PV) systems hold strong potential to accelerate the energy transition in the power sector. However, their implementation in Sweden presents specific challenges due to climate, infrastructure, and integration issues.

Tianqi Ruan’s doctoral thesis investigates the feasibility and performance of PV systems in Swedish contexts, using Stockholm as a case study. The research evaluates technical and economic potential by analyzing weather data, spatial conditions, system configurations, and financial metrics. Key findings include:

  • Annual snow-related generation losses are as high as 14.7%, higher than previously reported.

  • Bifacial PV technology significantly reduces these losses and outperforms monofacial PV in terms of cost and payback.

  • Wall-mounted PV systems may offer economic advantages during snow seasons, benefiting from higher energy prices.

  • An optimal tilt angle applicable across Swedish cities can increase energy output by 3–6%.

  • Climate projections show a potential 5% increase in PV generation by 2100, with minimal year-to-year variation.

🔗 Download the full thesis (DiVA)

Publications Included in the Thesis

The thesis is based on:

  1. Potential of grid-connected decentralized rooftop PV systems in Sweden

  2. A new optimal PV installation angle model in high-latitude cold regions based on historical weather big data

  3. Potential of Wall-Mounted Solar PV Panel in high-latitude areas-A case study in Swedish contexts

  4. Impact of climate change on the potential of photovoltaic power generation in Sweden over the next 75 years

  5. Techno-economic analysis of urban bifacial PV in high-latitude area

Opponent

Prof. Thomas Olofsson, Umeå University

Grading Committee

  • Prof. Joakim Widén, Uppsala University

  • Prof. André Augusto, Högskolan Dalarna

  • Assoc. Prof. Menglian Zheng, Zhejiang University

  • Dr. Maria Xylia, Stockholm Environment Institute (substitute member)

Supervisors

  • Main Supervisor: Prof. Björn Laumert

  • Co-supervisors: Dr. Monika Topel and Dr. Wujun Wang

Photo Highlights

During the defense
Celebrating afterward

Questions?

📩 For more information, feel free to contact Tianqi Ruan .

Tianqi Ruan
Symposium on Heat and Power Technologies for Industrial Decarbonization – 2025