The economic viability of a feed-in tariff scheme that solely rewards self-consumption to promote the use of integrated photovoltaic battery systems

With reference to an integrated photovoltaic battery (PV-BES) system for grid-connected end users, a feed-in tariff scheme is discussed in this article. This scheme solely rewards self-consumption. Zero is the generation price paid for the generated renewable energy, and zero is the export price paid for the renewable energy delivered to the grid. This feed-in tariff scheme, referred to as S-FIT, also excludes the net-metering service and the possibility that the grid recharges or discharges the batteries.To calculate the incentive tariff, an optimization problem is adopted. The problem returns the minimum value of the tariff so that the subsidy given to the end user is equal to the difference between the instalments paid for the integrated PV-BES system and the savings obtained from the electricity bill. The period during which the end user has secured this grant is ten years.The S-FIT scheme is applied to the case of the Italian Public Administration from 2011 to 2015. Consequently, the real values of temperature, irradiation, and energy consumption are measured every 15 min, and the real electricity prices over the period 2011–2015 are considered. The optimal solution returned by the optimization problem allows for a significant reduction of the electricity bill by 49.56%; moreover, the self-produced energy is equal to at least 50%, whereas the self-consumed energy is equal to at least 80%.The optimal solution that is calculated using 2011 data is applied for 2012–2015. Although the electricity prices were subject to a radical change during this period, the optimal solution still allows for a significant reduction of the electricity bill; in particular, this reduction is equal to 44.98% when the PV-BES system is adopted, whereas it is equal to 33.65% when only the PV system is adopted. In both cases, the optimal solution ensures self-produced energy of at least 50% and self-consumed energy of at least 80%.This article ends with an assessment of the impact of the integrated PV-BES system on the load profile from the grid perspective and the satisfactory degree of self-sufficiency achieved by the end user.