In the present paper, an analysis of the operation conditions of two flat plate solar collectors that differ in the geometry of the tube line system (harp and meander) is carried out. The collectors were tested to evaluate the influence of the type of system on the thermal parameters due to the geometric differences. In both cases, tubes with a thickness of 2 mm and an outer diameter of 30 mm were used. The working medium in the systems was water with an inlet temperature of 288K (15oC) and a velocity of 1m/s. Numerical investigations were carried out on full-scale simulations using the Ansys Fluent software. The conducted simulations provided information on the dynamics of changes in the operating parameters of the installation. The analysis showed that the efficiency of the system can be significantly improved by installing an appropriate absorber system. The results show that the greatest heating of the circulating medium occurs in the elbows and curves of the meander collector. After comparing the flows of the working medium through the meander and harp collectors, it was noticed that the meander collector is a more efficient system than the harp collector.