“…So, the results of this work are in a good agreement with those of Uba & Sarsah (2013) for the first and third periods while the result of Uba & Sarsah (2013) should be corrected for the second period because 1) the solar collector should be orientated to the North during April -August period and 2) the proposed value is too high. Ng et al (2014) found, for Bangi, Malaysia (L = 3° N), that Bopt,m = 22, 16, 5, -8, -18, -22, -21, -11, 0, 11, 19, 24 for January to December respectively. When calculating Bopt,m for theses months using the proposed methodology of this work one obtains that Bopt,m = 33.5°, 23.1°, 7.2°, -11.9°, -25.5°, -31.2°, -28.5°, -17.4°, -5.6° (12) Table 6) it was found that the results of (O) set of equations are not compatible with other results and they could not be justified.…”