The calculation of solar energy used by hot water systems in permafrost region: an experimental case study for Yakutia

Abstract This paper presents a mathematical model for the collection and efficient use of solar energy in hot water systems at permafrost regions. A case study was presented for northern territories of the Russian Federation in the Republic of Sakha (Yakutia). Daily maximum diffuse solar radiation on a horizontal and inclined surface was predicted during the year taking into account cloud coverage. The cloud coverage data was taken from the results of five-year monitoring on the heliometric station of the Yakutsk city. The modelling of the hourly, daily, monthly, and annual amount of solar radiation was performed. The mathematical model was turned and finally proved by experimental data obtained from the testing rig. The modelling of the domestic hot water supply system of particular northern territories was performed using solar energy and energy storage. Both models were integrated and verified by experimental data accounting a seasonal fluctuation. The estimation of the solar energy potential for practical application in Yakutia was executed. The operating features of permafrost regions were analysed by the developed experimental unit. The application of solenoid valve reduces the heat losses during the night by 57 % in June and by 69 % in November. The case study provides the results of modelling and efficient use of solar energy for different daily water flow rates during January and June. The results of the case study show the possibility to use of solar energy in a hybrid energy system at permafrost regions, decarbonize the energy input and contribute regional sustainability of northern territories.