ENGINEERING FOR RURAL DEVELOPMENT Jelgava, 27.-28.05.2010. 205 PECULIARITIES OF DOMESTIC WATER HEATING BY SOLAR COLLECTORS Ilze Pelece, Henriks Putans, Viktorija Zagorska, Liene Kancevica, Imants Ziemelis Latvia University of Agriculture imants.ziemelis@llu.lv Abstract. A lot of various types and modifications of solar collectors are known. Aimed to evaluate the possibilities of the use of solar collectors for warm water production in meteorological conditions of Latvia all over the year in the agency of the Latvia University of Agriculture (LLU), Research Institute of Agricultural Machinery (LTZI) in collaboration with Department of Physics of the Information Technologies Faculty in Germany produced vacuum tube type solar collector Vitosol 200 SD system with the collector area 3 m 2 was set up. Researches about efficiency of the solar collector (placed on the roof of the building) during December 2008 and in the first 11 months in 2009 were made in conditions of production in Ulbroka. Key words: collector of solar energy, temperature, warm water. Introduction To evaluate the possibilities of the use of solar collectors for warm water production in meteorological conditions of Latvia all over the year in LTZI in Germany produced vacuum tube type solar collector Vitosol 200 SD system with the collector area 3 m 2 was set up and operated. The system is not equipped with warm water registration meters, therefore HOBO H08 logger was used to estimate the warm water supply system completely, which registered water temperature inside the accumulation tank of warm water of the solar collector during the year. For this purpose HOBO temperature sensor is placed in the existing nest of the temperature sensor located inside the accumulation tank of warm water of the solar collector. The temperature values were registered with 15 minutes interval for each month separately. Making the data analysis of the diagrams (Figure 1) we can judge about the duration of operation of the solar collector during the corresponding period of time, warm water temperature variations inside the accumulation tank of the solar collector and increase of warm water temperature during the operation of the solar collector. Making the data analysis in the Excel program, i.e., getting empirical distribution of temperatures into the groups by the range of temperature values it is possible to get durations of warm water provision during a range of different temperature values. In the same way (if we know the amount of water in the accumulation tank and increase of the temperature value) it is possible to calculate the amount of heat energy produced by the heat collector during a definite period of time [1]. Using the data from the tables of the diagrams it is possible to calculate heat losses of the accumulation tank of the solar collector. In the course of the year power of global irradiance and charging power of the electric accumulator produced by the solar collector are registered as well. If we join global irradiance or the power of produced by the solar collector diagrams with the diagram of temperatures of warm water in the accumulation tank we can judge about the production capability of the solar collector in dependence on the power of solar irradiance. The aim of the research is to get a characteristic diagram of produced by the solar energy collector warm water temperature and distribution of days (amount) into the groups by the range of temperature values for separate months and for the whole year. Materials and Methods The most important element of the solar energy collector system is the warm water accumulation tank to which two loops are connected: the loop of the collector and the warm water loop. The elements of the loop of the solar collector are interconnected with copper tubes, through them heat carrier is circulating – conducting the heat gained in the solar collector to the accumulation tank. The elements of the warm water loop are interconnected with steel or plastic tubes (warm water is supplied to the users from the accumulation tank). The loop of the solar energy collector starting from the collector and going in the direction of the flow of the heat carrier is shown in the Figure 1. The loop of the solar energy collector consists of the solar collector 1 where in the output of the heat carrier temperature sensor 7 and air valve 18 are placed; the meter system 3 where the thermometer 4 is built in; heat exchangers 25 and 26; the system