Tilt optimization of a double-glazed air solar collector prototype Hocine Mzad, Abdessalam Otmani, Abdallah Haouam, Stanisław Łopata and Pawel Ocłoń MATEC Web Conf., 240 (2018) 04006 Published online: 27 November 2018 DOI: 10.1051/matecconf/201824004006