A b s t r a c t. The investigation was aimed at defining the characteristics of the hops drying process under the real condition in a solar dryer. The 25, 55, 85, and 115 cm thick hops layer were solar dried in 2x2 m boxes. This paper presents the results of changes in moisture content depending on each layer thickness at the unchanged fan power (0.5 kW, 3 900 m³/h). The paper also describes the changes in moisture content at different heights within the 85 cm layer. The energy consumption and the quantity of dried material were used as the criteria for defining the optimal thickness of a layer to be dried, which for the described type of equipment is about 55 cm. When the layers over 90 cm are dried in this type of a dryer, if the climatic condition are unfavourable and only solar energy is used, the hops may lose in quality. The height of the dried hops layer containing 9 % of moisture is around 70 % at the beginning of drying, when the moisture content was 73 %. No statistically significant differences in eteric oil, alfa-acid and humulen content have been found between the samples consisting of solar dried hops layer up to 85 cm, and the samples consisting of hops dried in dark drafty places.