Unfavourable scenario analysis of compensation mechanisms for excess energy in self-consumption photovoltaic installations in the Spanish residential sector

Self-consumption photovoltaic installations in the residential sector have great potential to mitigate the emissions associated with the current high consumption of fossil fuels. However, few studies analyse the technical and economic performance of these installations as a function of the electricity tariff contracted by the prosumer. This study provides a first approach to this idea, as well as analysing an emerging tariff in the Spanish electricity market, such as the virtual battery (solar piggy bank or net billing), which allows the entire bill to be offset with photovoltaic surpluses. A technical-economic analysis of a self-consumption photovoltaic installation connected to the grid is carried out for different peak power values, as well as for different consumption profiles and different electricity tariffs. The results show the importance of considering the prosumer's consumption habits, as these directly influence the performance of the installation. Thus, it is not possible to obtain a single optimal solution for all cases. Among other conclusions, it was found that for surplus-to-consumption ratios in the range of 130-180 % and above, the virtual battery tariff is the best economic option. one of the keys to tackling the existing problem of climate change [6]. Of all the renewable technologies, solar photovoltaic energy has experienced the greatest growth in recent years, which has been accentuated by the ease of integration of this technology in the residential sector and its high economic return compared to the level of risk [7,8]. During 2022, solar photovoltaic technology has followed the same trend as in previous years, i.e., standing out from other renewable technologies as the one that has increased the most, incorporating 4,498 MW to the national generation park, which has meant an increase of 29.4% over the previous year [9]. At the same time, Spain is consolidating its position as a world leader in solar energy, ranking first in the world in terms of the percentage of solar energy in the electricity supply, with a value of 19.1% [10]. Key words. Photovoltaic solar energy, prosumer, self-consumption, net metering.