In this paper aims to study the effect of the Tilt angle and Azimuth angle on Global irradiance of the Monocrystalline type PV module of off grid system for type fixed system in Alkhums city _ Libya using the PVsyst software. Where the study is carried out in two cases. The initial case is changed the value of the tilt angle from 0 degree to 90 degree in 10 step with freeze of azimuth angle on truth south and then at the second case it use the best value for the tilt angle as a fixed value and change the value of the azimuth angle from 310 degree to 40 degree in 10 step. To get the optimum tilt and azimuth angle for the month and year round of the year. The study showed the increase in solar radiation. Where the increase rate in the Global irradiance was 12.8%. The optimum tilt angle and azimuth angle for this study are 300 and 0.00 respectively. In order to validate the results, they were compared to other research
(Solar-Med-Atlas, Photovoltaic Geographical Information System).
Alkhums city ,Tilt angle, azimuth angle, effective irradiance.