In this paper, CONOPT solver, embedded in program GAMS, is proposed for optimal power flow analysis in distribution network with renewable energy sources. CONOPT solver possibilities have been tested on IEEE 33 test system solving a problem o f minimizing active power losses in the network. Locations and sizes o f renewable energy sources were taken form available literature. The results obtained using CONOPT solver have been compared with results obtained by using metaheuristic and hybrid algorithms. It is shown that the CONOPT solver gives better results in terms o f minimum values o f active power losses.