Enhancing flat plate collector efficiency with microtubes and sodium sulfate decahydrate-copper oxide PCMMuhammad Shehram, Muhammad Najwan Hamidi, Aeizaal Azman Abdul Wahab and Mohd Khairunaz Mat DesaSci. Tech. Energ. Transition, 80 (2025) 53DOI: https://doi.org/10.2516/stet/2025034