Domestic energy system operation with PV and V2G, to minimise running cost, and provide passive grid support

Today, the number of installed domestic PV systems is increasing, and more efficient appliances are used in households. This trend is a good signal for the UK Government, which has set a target to cut the UK CO2 emissions by 80% from 1990 levels before 2050. Further legislation was passed in 2019 to amend the target to 100% by 2050, to reach net zero emissions. However, with the increasing PV penetration, the level and direction of power flow on the UK electricity grid is less predictable, which brings challenges to current power grid and energy suppliers. Smart grid technology can solve the drawbacks of the PV penetration, and is the subject of significant investigation. In this thesis, hourly load profile modelling is introduced as the basis of the research, then a PV generation profile is determined for each typical size of PV system installed in the UK. An evaluation of the combined load and PV profiles throughout a year is carried out to address the sizing of an additional battery energy storage system. This facilitates an integrated domestic energy storage facility with renewable energy source, in order to create a win-win situation for both the customers and the grid. By using PV as an alternative energy source to power the home appliances, the system can reduce the dependence of household on grid energy, and it can shave the peak grid demand by managing the loads and exporting PV overproduction back to grid. Hence, the system can cut the electricity bill for customers and make profit by selling electricity to grid. The electricity tariff is considered when calculating the annual profit available, and conducting the system payback period for performance analysis.
EV integration to the household in the form of vehicle to grid (V2G) is then examined based on the models developed. The complete domestic energy system model, including photovoltaic (PV) panels, battery energy storage system (BESS) and electric vehicle (EV) is updated to evaluate the impact of the V2G on the payback periods for a consumer. With a series of control algorithms applied, along with possible electricity tariffs, minimum energy usage and relative payback period for each variation of PV and BESS sizes within a proposed system are calculated. A battery ageing model is then developed to consider the annual battery degradation cost. It is shown that an EV can be used as extended stationary energy storage, together with a household BESS, to enhance the overall system performance.