In Saudi Arabia, hot water for domestic uses consumes a great portion of home electricity. Thus, solar collectors can be considered as an important alternative to reduce the amount of consumed electricity. Therefore, in recent researches, a great attention was given to develop flat plate collector (FPC) with optimal performance. In this paper, a multi-objective modified imperialist competitive algorithm (MOMICA) was employed for optimizing the performance of a FPC. The optimization results showed a capability to reach higher FPC efficiency with a relatively small collector area and hence lower price. It has also been proved that the change of the insulator depth from 0.02 to 0.05 m has a strong influence on the system’s efficiency.