This paper presents the design of an autonomous dynamic adaptability system (ADAS) for maintaining the irradiance levels of a steady-state xenon arc lamp solar simulator (SS). The solar simulator is used to carry out indoor testing and accelerated age tests on photovoltaic (PV) cells at the Fort Hare Institute of Technology (FHIT). The ADAS was designed primarily for two reasons: Firstly, to maintain a set irradiance level, irrespective of external effects which may cause unintended irradiance drift or fluctuations, while carrying out indoor tests. Secondly, to achieve the solar simulator set point quicker, thus reducing temperature build up on the target area. At a cold start, the SS runs at 20% of its rated current (145 A). At 20% of 145 A, the simulator gave an irradiance of 145.97 Wm−2 with a non-uniformity of 1.02%, and a cell surface temperature of 24.9 °C. At 50%, the simulator produced irradiance of 501.30 Wm−2, with a non-uniformity of 1.53% and a cell surface temperature of 25.0 °C. The irradiance of 1000 Wm−2, with a non-uniformity of 3.26% and a cell surface temperature of 25.9 °C, was achieved at 90% of the rated current. From the results obtained, the ADAS demonstrates that it can reliably operate the SS with very minimal human–machine interaction. Through the autonomous dynamic adaptability, set irradiance levels are maintained in a steady-state solar simulator once the user supplies operational set points via the supervisory control and data acquisition (SCADA) interface.
South Africa is the most technologically advanced nation in Africa. However, the country is plagued with constant load shedding. The country receives about 2500 sunshine hours annually, with daily average irradiation levels of 4.5–6.5 kWh/m2. Despite these potentials, the use of electricity for domestic water heating is still prevalent in the country. The mass rollout of solar water heating (SWH) technologies in the low-cost housing sector across the country were met with massive failures. This study aims to assess the energy yield of a passive flat plate and an evacuated tube solar water heating system by evaluating the performance of these systems to address the energy crisis in South Africa. The flat plate (FP) and evacuated tube (ET) solar water heating systems were monitored for four days, characterised by varying sky conditions through instantaneous data measurement at 5 s. The parameters measured were water temperature, ambient temperature, irradiance at the plane of array, relative humidity, wind speed and direction. The results obtained show that a maximum irradiance of 1050 W/m2 was obtained on a clear day and corresponded to a hot water temperature of about 58 °C and 65 °C for the FP and ET, respectively. However, a cloudy day with a maximum irradiance of 400 W/m2 produced about 22 °C and 29 °C of hot water for the FP and ET, respectively. The results obtained in this study will guide stakeholders in the renewable energy sector towards employing SWH systems to replace or augment the electric geyser. Solar water heaters (SWH) can be used in the low-cost housing sector to provide hot water. Hence, the assessments in this study offer essential information for the deployment of these systems to reduce demand on the ailing South African electricity utility, Eskom, and mitigate climate change.
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