Optimizing Large-Scale Solar Field Efficiency: Latvia Case Study

Solar energy transformation technologies are increasingly being used worldwide in the district heating sector. In the Baltic states, only one district heating company has implemented a large-scale solar collector field into its thermal energy production system, which is analyzed within this research. In this study, we analyzed the first year operation of the solar field, solar collector efficiency, and several influencing factors, i.e., ambient air temperature, heat carrier flow, and the temperature difference between the supply and return heat carrier temperatures. The study includes collecting and compilation of the data, analyzing influencing factors, and data analysis using the statistical analysis method. In addition, the research presents a simplified multi-regression model based on the actual performance of a large-scale solar field, which allows for forecasting the efficiency of solar collectors by taking into account the main operational parameters of the DH system. The results show that solar energy covers around 90% of the summer heat load of a particular district heating system. However, they also show room for improvements in producing all the necessary heat in the summer using solar energy. The regression analyses show that the most significant correlation between all parameters examined was obtained in May, reaching R2 = 0.9346 in solar field efficiency evaluation. This is due to several suitable conditions for solar energy production, i.e., placing solar collectors at an angle for them to be the most productive, having enough space in the storage tank, and the demand for thermal energy being still higher than in the summer months

Multi-Criteria Analysis to Select Renewable Energy Solution for District Heating System

The research paper is focused on how to choose the most suitable renewable energy solution using multi-criteria analysis for a district heating system. Making choices is based on indicators – economic, environmental and social. In this case, the study used five indicators: resources costs, totals investments, reduction of greenhouse gas emissions, specific weight of renewable energy resources and impact on utilized land. Three situations have been compared – current situation: gas boiler, planned: solar collectors 21 595 m2 + accumulation tank 8000 m3 and alternatives: solar PV panels 5504 m2 – heat pump COP 3 are used in the estimation. The multi-criteria decision-making analysis shows that solar collectors 21 595 m2 + accumulation tank 8000 m3 are considered as the best alternative. The methodology is based on choosing a solution for a district heating company in Latvia

Climate Index for District Heating System

District heating (DH) has been highlighted as an important part in future carbon neutral energy supply. However, the performance of different DH systems varies a lot and the existing regulations do not always motivate DH companies to move toward more sustainable heat production. Therefore, this article presents novel methodology for Climate index determination which can be further used for the comparison of DH systems. The Climate index includes seven different indicators which show DH system performance according to energy efficiency, sustainability and environmental impact dimensions. The methodology is applied for 20 different DH systems operating in Latvia. The results show that the performance of 5 natural gas-based DH systems is below the determined climate benchmark