Utilization of Electrical Energy Storage in Residential Buildings with Small-Scale Photovoltaic Production: Techno-economic research perspective

The need for flexibility in the power system will continue to increase when electrification progresses, and electricity production becomes more weather dependent. Small-scale energy production in residential buildings has become increasingly popular for alleviating rising energy costs. Simultaneously, requirements for the electricity grid increase when the grid should be capable of transferring increasing amounts of energy with a higher variation in demand and production. The grid also needs to be capable of receiving surplus energy from customers. Energy storage in residential buildings can decrease the pressure to reinforce the grid, reducing the costs for all customers. The poor profitability of battery energy storage systems has slowed down to become these systems more common. This thesis studies methods that illustrate how profitability can be increased and how specific factors can impact profitability.

Customers will invest in energy storage more likely if it is profitable. Currently, investment prices have decreased, battery lifetime has been optimized with better manufacturing, and new control systems can ensure the state of health of the battery. Profitability depends on the economic benefits of battery usage. Many incentives can affect the control targets of energy storage. Storage can be used to increase photovoltaic self-consumption or decreasing the maximum peak power or market-price-based control. This thesis examines the profitability of energy storage by utilizing simulations with measured data and modelled energy resources. Further, energy storage utilization is optimized using developed control algorithms with various control targets. Simulations conducted in this study led to many conclusions, including the identification of factors that affect the profitability of energy storage and methods that can determine how profitability can be increased.

Profitability can be increased by sizing photovoltaic systems with a battery and combining different control targets correctly. Distribution system operators can steer storage by correctly designing tariffs. Switching from hourly measurements of electricity billing to 15-min periods can increase the profitability of energy storage. Further, controlling the load in demand response operations can replace some storage capacity requirements; however, this decrease is negligible in terms of the profitability of the parallel-used battery energy storage systems. The use of energy storage can help increase the size of photovoltaic systems. Establishing energy communities expands the potential for utilizing energy storage with even larger photovoltaic systems.