# Simulation of Self-Consumption Photovoltaic Installations: Profitability Thresholds
## 1 Introduction
[18] present a methodology that maximises self-consumption based on daily consumption profiles and on the characteristics of the facility itself, regardless of the regulations applied. [PERSON] and [PERSON] [19] also developed a methodology for isolated installations in which their dimensioning was detailed for changing conditions throughout the year in orientation and demand. In the literature there are also methodologies that abound in the number of residents of each household. [PERSON] et al. [20] establish a ranking based on this methodology, as well as on the regulations of several European countries, highlighting the case of France. The complete work developed by [PERSON] et al. [21] which, although it focuses empirically on Spanish facilities, establishes a methodology that encompasses the barriers and incentives that prosumers find at various levels (economic, technological and regulatory) in southern European countries and Germany. It is noteworthy that in this work possible changes in the policies of the states leading to an increase in self-consumption are pointed out. Focusing on the Spanish case, it is worth analysing the evolution of the legislation that has generated an increase in the expectations of the sector in the last three years. The entry into force of Royal Decree 244/2019 [22] together with Royal Decree Law 15/2018 [23] promotes an energy transition towards Renewable Energy Sources (RES) and establishes the following changes regarding self-consumption: the end of any Tax charge on photovoltaic generation (sun tax, Royal Decree 900/2015 [24]), production surpluses can be discharged into the electricity grid in exchange for compensation (Figure 1), there is no limitation to the installed power and there is the possibility of collective self-consumption among several users, allowing the implementation of dynamic coefficients of use. This new legal framework offers various options for those consumers that feed surpluses into the grid (Figure 1). The surplus compensation mechanism with the demanded energy is available for those stations with power under 100 kW; those whose power exceeds that value or if preferred, will manage the surplus sales directly from the wholesaler market. The rest of the auto consumers, which represent most of the installations in service, have a regulated tariff (PVPC) where the surpluses price is stablished in the 24 h period prior to the service, or have a contract with a trading company, the latter one meaning that the surpluses price is stablished bilaterally. Since the Spanish regulation came into force, there have been several studies that present a changing and hopeful horizon regarding the increase and profitability of self-consumption in Spain. For an average household, it is more profitable to become a prosumer (1.5-2.0 kWp) than to remain just a consumer [25]. At the same time, another study [10] shows the different options that a prosumer can currently implement to increase the profitability of their installation, detailing the level of increase based on the percentage of self-consumption implemented. It is no less important to note that the authors also point out the possible risks of increased self-consumption with respect to integration costs. The study that shows how, regardless of the region or work zone chosen in Spain and whether or not the prosumer is paid, the performance is guaranteed [26] is interesting. This regional distribution of the study would facilitate the adoption of corrective measures at the legislative level depending on the area in which they worked. Along with the classic profitability studies in which a standard installation is used, it is interesting to combine the enormous amount of academic work carried out focused on relating urban morphology and possible obstructions with solar capture and energy production. An example is the one developed by [PERSON] et al. [27] in which the impact that the angle of obstruction has on the performance of solar panels in three European cities is studied.