The increase in the electricity bills and the new opportunities to participate in the electricity market has encouraged companies with activities not related to the energy industry to engage and actively participate in the electricity market to reduce costs and become more competitive. With the overarching goal of making cost-effective investments and decarbonizing their operation, the first step to improve these companies’ bottom line is to comprehend their electricity costs. This paper focuses on detailing a methodology to model electricity commercial bills and generate real-time price curves; thus allowing customers to calculate their half-hourly true cost of electricity and to assess the challenges of reaching net zero energy buildings for different UK regions and connection voltage levels, across every month up to the financial year 2019-20.