Optimal Collector Tilt Angle to Maximize Solar Fraction in Residential Heating Systems: A Numerical Study for Temperate Climates

Krzysztof Kupiec () and Barbara Król ()
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Krzysztof Kupiec: Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24 St, 31-155 Cracow, Poland
Barbara Król: Faculty of Chemical Engineering and Technology, Cracow University of Technology, Warszawska 24 St, 31-155 Cracow, Poland

Sustainability, 2025, vol. 17, issue 14, 1-16

Abstract: The performance of solar thermal systems for space heating and domestic hot water (DHW) production depends on the tilt angle of solar collectors, which governs the amount and seasonal distribution of captured solar radiation. This study evaluates the impact of fixed collector tilt angles on the annual solar fraction ( SF ) of a solar heating system designed for a typical single-family house located in Kraków, Poland (50° N latitude). A numerical model based on the f -Chart method was employed to simulate system performance under varying collector areas, storage tank volumes, heat exchanger characteristics, and DHW proportions. The analysis revealed that although total annual irradiation decreases with increasing tilt angle, the SF reaches a maximum at a tilt angle of approximately 60°, which is about 10° higher than the local geographic latitude. This configuration offers a favorable balance between winter energy gain and summer overheating mitigation. The results align with empirical recommendations in the literature and offer practical guidance for optimizing fixed-tilt solar heating systems in temperate climates.

Keywords: solar collector; tilt angle; solar heating system; annual energy efficiency (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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