Performance Analysis of Selected Forced Circulation Solar Thermal Installations at the University of Botswana - A Comparative Study

Abstract

This study undertakes a comprehensive monitoring, evaluation and comparative analysis of forced circulation solar thermal installations at the University of Botswana. The primary aim is to conduct a performance audit to determine the operational efficiency, reliability and hot water delivery effectiveness of forced circulation solar thermal systems installed in student hostels over a one-year monitoring period. The methodology involved system identification, real- time data collection using Winsol and CMI software and performance evaluation using key metrics such as useful heat gain and collector efficiency. Results revealed significant performance variations across the systems. While one system achieved an overall efficiency of 79% and solar fraction of 74%, others underperformed at efficiency of 4-8% due to excessive thermal losses, possible data acquisition errors and operational issues including pump failure and insulation degradation. Key challenges identified included data inconsistency, potential scaling in pipes, insulation-related thermal losses, reliance on electric backup during low radiation and temperature fluctuations. Despite these challenges, the systems significantly reduced electricity consumption, with solar fractions reaching up to 80% in optimally performing systems. The findings validate the practical viability of large-scale forced circulation systems in institutional settings and provide a replicable framework for sustainable energy management. The study also highlights the need for regular maintenance, sensor calibration and robust data logging to ensure reliable long-term performance.