Volume 5: Innovative Solutions for Energy Transitions: Part IV

Comparison of the Optimal Design of PV-Battery and PV-PHS off-Grid Energy Systems-a Case Study in Sweden Masoume Shabani, Erik Dahlquist, Fredrik Wallin, Jinyue Yan



This study deals with the investigating of the potential of employing two energy storage technologies., i.e. battery storage and pumped hydro storage (PHS), for PV powered supply system on a small island in Sweden. The optimal design of two hybrid PV-Battery and PV-PHS systems are compared and analyzed. Genetic Algorithm (NSGA-II) is employed as the optimization algorithm. Investment cost and loss of power supply probability are considered as objective functions. Number of PV modules and battery capacity are considered as design variables for PV-Battery system and a wide range of design variables including number of PV modules, turbine capacity, pump capacity, volume, installation height and depth to diameter ratio of reservoir, pipes diameters constitute for PV-PHS system. As a result, a hybrid pareto front is proposed for case study, that means, regarding objective functions, designer can decide that which of two systems are more suitable for current case study. The results show that pareto fronts of two hybrid systems intersect each other at a point. In this case, PV-PHS led to the lower pareto front for LPSPs up to about 6.94% and for LPSPs higher than 6.94%, pareto front of PV-PHS system lies above that of PVBattery system. This implies that under LPSPs range of 0- 6.94%, the PV-PHS system resulted in the lower initial cost, therefore, it is better option for the current case study. In contrast, for LPSPs higher than 6.94%, for the same LPSP, PV-Battery system led to the lower investment cost in comparison with PV-PHS, so it can be chosen as a better option regarding designer’s priorities. Also, results show that the proposed strategy can reach a design with the full satisfaction of fluctuating demand and system constraints. In this case, for the yearly average demand of 16.3 kW, the investment cost is obtained to be 2.1M$ and 1.87 M$ for the PV-battery and PV-PHS, respectively. The paper compares in detail the optimal designs and operations obtained for the two hybrid PV-Battery and PV-PHS systems.

Keywords PV-Battery, PV-PHS, Optimal design, Sweden

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