In 2008 a micro PV-Diesel Hybrid system has been installed at the Ihushi Development Center (IDC) near Mwanza in Tanzania. In April 2011 a monitoring system was installed at IDC to study the system performance and the usage of the system. Measured data from April to July 2011 have been used to model the system with the simulation software HOMER. One question was if HOMER allows accurate modelling and simulations of the actual system. In addition, it has been studied if the current system can be optimized and what system design solutions are most promising when the system need to be redesigned for a higher load.