Conference article

Retrofitting Domestic Hot Water Tanks for Solar Thermal Collectors. A Theoretical Analysis

Luís Ricardo Bernardo
Energy and Building Design, Lund Technical University, Lund, Sweden

Henrik Davidsson
Energy and Building Design, Lund Technical University, Lund, Sweden

Björn Karlsson
Mälardalen University, Västerås, Sweden

Download articlehttp://dx.doi.org/10.3384/ecp110573765

Published in: World Renewable Energy Congress - Sweden; 8-13 May; 2011; Linköping; Sweden

Linköping Electronic Conference Proceedings 57:13, p. 3765-3772

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Published: 2011-11-03

ISBN: 978-91-7393-070-3

ISSN: 1650-3686 (print), 1650-3740 (online)

Abstract

One of the most expensive components of a solar thermal system is the storage tank. Retrofitting conventional domestic hot water heaters when installing a new solar hot water system can decrease the total investment cost. In this study; retrofitting of existing water heaters using forced circulation flow was investigated. A comparison with a standard solar thermal system is also presented. Four simulation models of different system configurations were created and tested for the climate in Lund; Sweden. The results from the simulations indicate that the best configuration consists on connecting the collectors to the existing heater throughout an external heat exchanger and adding a small heater storage in series. For this retrofitted system; preliminary results show that an annual solar fraction of 53% is achieved. In addition; a conventional solar thermal system using a standard solar tank achieves a comparable performance for the same storage volume and collector area. Hence; it is worth to further investigate and test in practice this retrofitting. Furthermore; using the same system configuration; solar collectors can also be combined with new standard domestic hot water tanks at new installations; accessing a world-wide developed and spread industry.

Keywords

Solar thermal; Storage tank; Water heater; Retrofit; Domestic hot water

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