Design and Performance Evaluation of Low Cost Domestic Solar Water Heating System in Kenya
| dc.contributor.author | Kwach, Sarah Acholla | |
| dc.date.accessioned | 2026-03-11T09:56:56Z | |
| dc.date.available | 2026-03-11T09:56:56Z | |
| dc.date.issued | 2025-11 | |
| dc.description | A Thesis Submitted in Partial Fulfilment of the Requirements for the Award of Degree of Master of Science (Renewable Energy) in the School of Engineering and Technology of Kenyatta University, September, 2025 Supervisor; 1.Mary Makokha 2.Moses Makayoto | |
| dc.description.abstract | Kenya’s energy consumption is dominated by biomass, with an estimated 75% of households relying on firewood and charcoal for cooking, heating, and lighting. This dependency accelerates deforestation, contributes to indoor air pollution, and poses severe health risks. Yet, Kenya’s equatorial location provides abundant solar energy, averaging 4–6 kWh/m² per day, making solar water heating (SWH) a sustainable and eco-friendly alternative. Despite this potential, SWH technology adoption has been limited due to high installation costs, dependence on imported copper collectors, and inadequate local manufacturing capacity. This study focused on the design, construction, and evaluation of low-cost flat plate solar water heating systems (FPSWHS) using locally available materials, tested under real Kenyan climatic conditions. The experiments were carried out at Kenyatta University in Kiambu County (1°10'50.0"S, 36°55'41.0"E) between March and May 2015, a period marked by alternating sunny and cloudy weather patterns. Two prototype systems were developed: System A, incorporating an aluminum absorber plate, and System B, utilizing galvanized steel. Both were designed and fabricated locally at the Kenya Industrial Research and Development Institute (KIRDI). A commercially manufactured copper-based collector imported from China (System C) was used as the control. System sizing was based on the estimated hot water demand of a typical five-member household, with each person requiring approximately 20 liters of water heated to 50°C per day. Using local solar irradiance data (approximately 800 W/m²), estimated daily water consumption, and standard thermal design equations, each system was optimized to efficiently meet domestic hot water needs The experimental setup comprised three flat plate solar water heating systems, each with a collector area of 2 m², tested simultaneously under actual field conditions. Solar radiation was measured using a pyranometer, while outlet water temperatures were recorded hourly using digital thermometers positioned at the outlets of each system. All three systems successfully heated water above the 50°C threshold recommended by the World Health Organization (WHO) for safe domestic use. The highest outlet temperatures recorded were 78.7°C for the copper collector, 74.1°C for aluminum, and 69.4°C for galvanized steel, with corresponding mean outlet temperatures of 63.5°C, 61.2°C, and 57.3°C, respectively. Thermal efficiencies were calculated as 34.0% for copper, 32.8% for aluminum, and 28.8% for galvanized steel. Although the galvanized steel system demonstrated the lowest efficiency, it was the most economical, costing Ksh 45,996.80 (USD 353.82), which is approximately 20% less than the aluminum system at Ksh 54,160 (USD 416.61) and significantly cheaper than the copper system at Ksh 68,664 (USD 528.18). Additionally, the aluminum collector showed a payback period of 24 months, indicating a favorable balance between performance and investment. The findings demonstrate that low-cost, locally manufactured solar water heating systems— particularly those constructed with galvanized steel—offer an affordable, sustainable, and effective solution for meeting domestic hot water needs in Kenya. The widespread adoption of such systems has the potential to significantly reduce reliance on biomass fuels, thereby mitigating environmental degradation and deforestation. Additionally, improved access to clean hot water can enhance public health outcomes by reducing waterborne diseases and improving hygiene. These benefits align with the objectives of Kenya’s Vision 2030 and contribute to the achievement of global sustainability goals. | |
| dc.description.sponsorship | Kenyatta University | |
| dc.identifier.uri | https://ir-library.ku.ac.ke/handle/123456789/32705 | |
| dc.language.iso | en | |
| dc.publisher | Kenyatta University | |
| dc.title | Design and Performance Evaluation of Low Cost Domestic Solar Water Heating System in Kenya | |
| dc.type | Thesis |