A long-term performance analysis of three different configurations for community-sized solar heating systems in high latitudes

Abstract

This paper proposes various community-sized solar heating systems configurations for cold climate. Three configurations were proposed, (I)a heat pump connected to two tanks in parallel, using charged borehole storage, (II)a heat pump connected between two tanks, using charged borehole storage to directly charge the lower temperature tank, and (III)two heat pumps used in series, one between the tanks and the other between the lower temperature tank and ground. In configurations (I) and (II) the vertical borehole field is used as a seasonal storage, in (III) it is used to extract heat only. The studied energy flows are heat and electricity. The border consists of energy production systems, heating grid and buildings. The impact of the considered system solutions on the heating renewable energy fraction, on-site electrical energy fraction, purchased energy and full cost as a function of the demand, solar thermal and photovoltaic areas, tanks and borehole volumes has been evaluated. The dynamic simulations results shows that an average renewable energy fraction of 53-81% can be achieved, depending upon the energy systems' configuration. Furthermore, Energy System II utilizes less energy compared to other systems. In all three systems medium-sized solar thermal area is more beneficial instead of large area.

Design and Optimization of a De-Centralized Community Sized Solar Heating System for Nordic Region

“…Each method provides certain advantages such as location, capacity and cost. Among these four methods, BTES is the most flexible storage technique (Rehman, et al, 2017) and therefore is the primary focus of this analysis.…”

“…It is found that charging of the ground can improve the heat pump performance as the evaporator temperature increases. Hence, it improves the coefficient of performance (COP) of the heat pump (Rehman, et al, 2017). The heat pump can be integrated with the solar thermal system in multiple ways and with varying control strategies.…”

“…While the de-centralized part consists of a small tank in each individual house that operates at higher temperature, it is being charged by the centralized tank and heat pump, and part of the space heating along with domestic hot water is provided through this tank. In this configuration the placement of the heat pump, hot short term storage tank and the overall control strategy is altered compared to the previous studies (Rehman, et al, 2017), (Sibbitt, et al, 2012). In the previous study carried out, the heat pump is centralized with the two large centralized short term storage tanks charged via solar energy and seasonal storage in parallel (Rehman, et al, 2017).…”

“…In this configuration the placement of the heat pump, hot short term storage tank and the overall control strategy is altered compared to the previous studies (Rehman, et al, 2017), (Sibbitt, et al, 2012). In the previous study carried out, the heat pump is centralized with the two large centralized short term storage tanks charged via solar energy and seasonal storage in parallel (Rehman, et al, 2017). These large tanks are divided into warm and hot tanks in order to meet the space heating (SPH) and domestic hot water demand (DHW) of the community respectively (Rehman, et al, 2017).…”

“…In the previous study carried out, the heat pump is centralized with the two large centralized short term storage tanks charged via solar energy and seasonal storage in parallel (Rehman, et al, 2017). These large tanks are divided into warm and hot tanks in order to meet the space heating (SPH) and domestic hot water demand (DHW) of the community respectively (Rehman, et al, 2017). Whereas in the present study, instead of a large centralized hot tank, a small tank is places in each of the 100 houses.…”