Optimising behind-the-meter solar for water distribution systems: impact of network configuration and electricity tariff structure

Abstract

This research investigates the impact of different water distribution system (WDS) network configurations (i.e., with and without elevated water tanks) and various electricity tariff structures on the behind-the-meter (BTM) solar PV system design for WDSs and their overall performance. Two network configurations (i.e., with and without elevated water storage tanks) and three electricity tariff structures (i.e., zero, fixed and dynamic purchase or grid feed-in tariffs) have been investigated using two case study systems. It has been found that WDS configurations with elevated tanks typically require larger BTM solar systems, offering greater flexibility in aligning pump operations with solar energy generation. This in turn leads to higher solar energy utilisation and lower total life cycle costs (TLCC) compared to systems without tanks. In contrast, WDSs without elevated tanks tend to have smaller solar PV systems and may have low efficiency in solar energy utilisation. In addition, it has been found that although a fixed grid feed-in electricity tariff offers additional revenue through selling excess solar energy back to the grid, it has minimal impact on solar PV sizes. In contrast, a dynamic electricity tariff structure leads to smaller BTM solar systems but higher TLCC due to the impact of possible negative electricity prices. Overall, this research offers valuable insights into the design and operation of WDSs integrating BTM solar, providing guidance on determining optimal solar PV sizes based on WDS configurations and different electricity tariff structures to maximise economic and energy benefits in these integrated systems.