الفهرس 
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Abstract
Solar stills are used in distant and arid areas to convert brackish or salty water into potable water fit for human use in a simple, affordable, as well as effective manner. Even when PCM materials are used, typical solar systems have minimal production per day. In this study, experimental tests were carried out in order to increase the performance of a single slope solar still combined with PCM material (paraffin wax) and a solar-powered electric heater. Two identical single‒slope solar stills were designed, fabricated and tested under the same climatic conditions during the summer, spring and autumn seasons 2021 in Al-Arish city, Egypt. The first one is a conventional type solar still (CVSS) and the other still is a conventional with PCM and electric heater (CVSSWPCM and electric heater). The electric heater was supplied with power directly by a PV system where fixed in the same place of the two solar stills. The electric heater was installed in the centre of the paraffin wax reservoir where located directly beneath the absorber plate of the modified still. Several parameters were measured during the experiment, including solar intensity, meteorological aspects, accumulative productivity from the two stills, and average basin water, glass, and paraffin wax temperatures. The performance of the modified solar still was evaluated at different operating temperatures and compared to the performance of the conventional one. There were four cases studied: without a heater (paraffin wax only) and with a heater operating from the beginning of experiment at 58 oC, 60 oC, and 65 oC. Also different water depths cases were studied for the two solar stills at 65 oC operating temperature conditions for the modified solar still. The resulting experimental outcomes revealed that the daily accumulated productivities of CVSSWPCM (paraffin wax only) are enhanced by 14%, 17%, and 16% at spring, summer and autumn respectively. The accumulated productivities of CVSSWPCM and heater are enhanced by 172.5%, 158.8% and 446% at control temperature of heater 58 °C at spring, summer and autumn respectively. The accumulated productivities of CVSSWPCM and electric heater are enhanced by 203.5%, 181.3% and 513% at control temperature of heater 60 °C at spring, summer and autumn respectively. The accumulated productivities of CVSSWPCM and electric heater are enhanced by 252.4%, 214.5% and 586% at control temperature of heater 65 °C at spring, summer and autumn respectively.