The Thesis analyzes one of the spheres of alternative energy supply – the solar energy. The main objective of the Thesis is to determine the energy rates of the solar collector and its accumulative capacity. The Paper introduces a stand on the solar collector research which consists of a flat solar collector, heat accumulator and auxiliary equipment. The research object of the Thesis is a laboratory flat solar collector and its system. The Thesis analyses the constructions of the solar collector which is meant for water heating. For this purpose theoretical research has been made, and experimental tests have been performed in a confined room by using a simulator of solar radiation and blowing the solar collector at an average wind speed of 2 m/s. Tests on the energy characteristics of the solar collector have been performed by using transparent poly-carbon covering and the glass covering; without using transparent covering and changing the debit of the heat-carrier. The author has made the reliance of the solar collector and accumulative capacity on the in-flowing and out-flowing heat-carrier and differences of the environment temperatures by using different coverings and debits of the heat-carrier. The relation between the accumulative capacity of the solar collector and the dimension of the solar collector has been established.