Design of Solar Water Heater Using Collector Cylindric Parabolic and Coil Heater as Absorber at Focus PointSari Farah Dina, Jufrizal, Siti Masriani Rambe, Harry P. Limbong and Edwin H. SipahutarE3S Web Conf., 328 (2021) 07016DOI: https://doi.org/10.1051/e3sconf/202132807016