Standalone Home Battery Systems in the UK: An Assessment of Economic Viability with Consideration of Additional Impacts

Abstract

There have been several studies conducted on the economic viability of home battery systems paired with rooftop solar PV systems over the years; however, there have been far fewer studies looking into the economic viability of standalone home battery systems, which is the main area assessed in this study. Rather than being used to store excess solar generation, a home battery system is used with time-of-use tariffs to take advantage of cheaper, off-peak rates. This works by charging the battery overnight at the off-peak rate and drawing electricity from the battery during the day, rather than from the grid at the more expensive peak rate. This study found only one of the four assessed home battery systems to be economically viable for this application, with a net cash flow of GBP 1842 over its 12-year lifetime, a return on investment of 33%, and a payback period of 9 years. Beyond their potential to save money on electricity bills, this study also investigated the potential of home battery systems to prevent GHG emissions by considering the variation in the carbon intensity of the grid between peak and off-peak times. The economically viable system has a lifetime emissions prevention potential of 308 kg CO2-e. However, when compared with the emissions associated with its manufacture based on an LCA study of home battery systems, the manufacture of the system causes more emissions than it prevents throughout its life by 1754 kg CO2-e. This shows that the systems do not have a positive impact on the environment in this respect. However, this study also considers some additional impacts of home battery systems to discuss whether they could have an overall positive impact, such as by improving grid stability, which helps facilitate the implementation of renewable energy generation.