Comparative evaluation of two photovoltaic multi-pump parallel system configurations for optimal distribution of the generated power

Abstract

The suitability of a strategy for distributing the power generated by a photovoltaic pumping system equipped with two equal pumps working in parallel is proven. This strategy aims to improve energy management and consists of feeding a single pump with all the power generated until it exceeds a threshold value from which the power distribution must be at 50% between the two pumps. This pumping method was compared with the operation mode usually applied in parallel PV pumping facilities (50% of the power always assigned to each pump). A system equipped with two 0.75 kW pumps was employed. The assessment of the facility’s performance under the two alternative working conditions and several pumping heads was conducted using simulation techniques. Both the pumped annual volume and the annual efficiency of the motor-pump group increased when the strategy was applied compared to operation with power distribution at 50%. This increase was greater the higher the head (6.21% at H = 18 m vs. 57.60% at H = 48 m for pumped annual volume and 6.42% at H = 18 m vs. 57.51% at H = 48 m for annual efficiency). The halving of the irradiance threshold and the improved efficiency (36.4% vs. 34.8%) may explain this increase.