Development and performance evaluation of indigenous flat plate solar water heating systems under Kenyan climatic conditions

Year 2025, Volume: 9 Issue: 3, 207 - 228, 30.09.2025

Sarah Kwach , Thomas N. Thoruwa Mary Makokha , Emmanuel Y. Kombe Moses Makayoto

https://doi.org/10.30521/jes.1512933

Abstract

This work presents the performance of three solar water heaters equipped with 2 m2 flat plate collectors. The experimental setup included a copper absorber plate manufactured in China (System C), along with two locally built flat plate collectors. One collector was made of aluminum material (System A), while the other was made of galvanized steel material (System B). The systems were tested over a period of three months. For systems A, B, and C; the average maximum outlet water temperatures were measured as 74.1 oC, 69.4 oC, and 78.7 oC, respectively. Systems A, B, and C had mean water outlet temperatures of 61.2 oC, 57.3 oC, and 63.5 oC, respectively. The efficiency of the aluminum-based flat plate collector was 32.8%, slightly below the copper-based flat plate collector, which reached an efficiency of 34%. On the other hand, the galvanized flat plate collector exhibited the lowest thermal efficiency of 28.8%. It can be inferred that even though the galvanized steel solar water heater had low thermal efficiency, it was 20% more cost-effective than systems constructed from copper and aluminum. These results would contribute to the widespread adoption of the inexpensive solar water heaters produced in the region as a reasonable alternative to conventional energy sources including biomass.

Keywords

Collector , Flat plate , Low-cost , Performance , Solar , Water heating

Ethical Statement

The authors have no conflicts to disclose. or personal relationships that could have appeared to influence the work reported in this paper.

Supporting Institution

Kenyatta University

Project Number

001

Thanks

I would like to convey my heartfelt gratitude to my supervisors; Prof. Thomas Thoruwa, Dr.Moses Makayoto and Dr.Mary Makokha for their priceless time, direction, constant motivation, and recommendations throughout this research work, without which this publication would not have been as herein presented. I also convey my appreciation to all the KIRDI’s Management Team for the funds provided to support the acquisition of materials during the design and manufacturing stages of the project and their guidance and support throughout the process. Gratitude is also expressed to Kenyatta University and particularly Former chairman Mr. Elias Ako and the current Chairman of Energy department, Dr. Njoka, for granting me permission to utilize their location and resources for my research and trials, as well as Dr,Emmanual Yeri for his time, words of motivation and excellent backing in the reviewing the document and to the technical people; Bernard Onyango and Maurice Asunda for their resilience and tremendous effort they provided during the construction and assembly of the systems. Many gratitude also go to Rael Achieng of Kenya Marine and Fisheries Institute-Mombasa who assisted in the examination of data. I express my gratitude to the DIVINE for all his favor, blessings, and benevolence.

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