# Simulation of Self-Consumption Photovoltaic Installations: Profitability Thresholds
## 1 Introduction  
Dependency on energy imports is still a reality in many countries today. Europe suffers from this problem very unevenly. Spain is one of the countries with the greatest demographic and economic weight within Europe that suffers from energy dependency and this shortfall is made up by energy imports of fossil origin. It has only been through applying renewable technologies that in some countries this dependency has improved. At an economic level it has a negative effect on the balance of payments and the country's debt capacity and also contributes to raising the cost of financing these imports [1]. Also, at an environmental level, the impact on climate change is very high [2]. Specifically, in the case of Spain, dependency stood at around 74% in 2017 (mainly oil and natural gas) and reached 20,700 million euros [3]. Therefore, reducing this dependency is a challenge long discussed at a political level in Spain, although there has not been a clear policy whose objectives were aimed at its reduction. The National Integrated Energy and Climate Plan (PNIEC) 2021-2030 of Spain aims to advance in the improvement of energy dependency abroad to reach 61% in 2030 [4]. Reducing this dependency can be tackled in Spain using its own resources and with a greater share of renewable energies in the country's energy mix. Specifically, the potential of solar energy in Spain is clear given that it is one of the European countries with the highest rate of solar radiation. Thus, for example, Madrid is the European capital with the highest direct radiation (3.39 kWh-m-2-day-1) and the second, after Athens, in globalradiation levels (4.88 kWh\(\cdot\)m\({}^{-2}\cdot\)day\({}^{-1}\)) [5]. In this context and due to the sharp decrease in costs that it has experienced in recent years [6], the photovoltaic sector is key to this strategy [7]. It has therefore become the spearhead of the objectives of the Clean energy for all Europeans package [8] to generate a decarbonized energy model. Furthermore, it is a technology with a high capacity to generate employment [9]. However, the different changes that Spanish regulations have undergone regarding energy [10; 11; 12] have generated certain instability in the solar sector. In the scope of this work, the authors will focus on photovoltaic (PV) self-consumption. A self-consumption PV installation is a PV plant that allows the owner to generate their own electrical energy from solar energy through PV panels. In addition, the installation is connected to the network, so that when the demand exceeds the self-produced energy, the difference is taken from the electrical network. The concept of pro-sumer is introduced as the user of the electrical system that not only consumes energy but also produces it [13]. It is important to highlight the influence that legislative regulation has on the implementation of such technology. The high impact that the different policies a country may adopt on energy consumption habits [14] and, therefore, on global terms of demand is noteworthy. [PERSON] et al. [15] conclude that without a clear support policy for self-consumption there are many drawbacks, mainly investment, that prosumers encounter for the development of this sector at the residential level in Chile. In this regard, [PERSON] et al. [16] have already established the limitations and the technological and administrative possibilities that would generate a profitable system in Germany and Ireland. [PERSON] et al. [17] established the conditions for the development of business models under different regulations, summarising the possible options in five profiles based on the comparison between the retail price and the LCOE. At the time of its publication, it was still in an incipient stage both at the legislative and implementation levels. To carry out a complete study of the profitability conditions of a photovoltaic installation for self-consumption, it is also necessary to detail the dimensioning of the installations. Thus, [PERSON] et al.