## 5 Current Tariff Situation  
As discussed above, across the EU, electricity prices are mainly affected by fossil fuel costs and carbon emission allowances. In addition, power generation from renewable sources such as solar and wind has started to reduce prices in certain countries due to their increasing competitiveness. However, retail electricity costs are not uniform across countries, as governments take varying measures to mitigate the effects of recent energy crises, such as those caused by the war in Ukraine and the pandemic. It is therefore essential that policymakers develop long-term strategic energy planning [17]. It is also important to bear in mind that consumers in countries such as Spain and Portugal have received aid to curb the impact of wholesale prices. In contrast, in other countries such as Germany and Italy, costs have been more volatile. This aspect is an important factor when choosing which tariff is more appropriate depending on the country. Some countries are also applying special tariffs to incentivize the installation of renewable energies, which is directly linked to the assessment of the profitability of the PV installation. Below are the most relevant tariffs in some EU countries:  
1. Spain: * Time discriminatory tariff (TDH): this tariff varies according to the time of day. It is divided into two or three periods (peak, flat and valley), with the valley being the cheapest. Figures 4 and 5 illustrate the allocation of periods to specific hours, contingent on the day of the week. * Indexed prices: prices vary according to the wholesale market, allowing consumers to take advantage of times of low demand to pay less, but exposing them to higher prices at times of high demand. * PVPC tariff (Voluntary Price for Small Consumers): the price varies every hour according to the wholesale market, regulated by the government. 2. Germany: * Fixed vs. variable tariffs: electricity tariffs in Germany are highly influenced by environmental taxes and the cost of renewable energies. Consumers can choose between tariffs with long-term fixed prices or variable tariffs that fluctuate according to the market. * EEG-Umlage: this is a specific surcharge to finance renewables, which is added to the basic cost of electricity. 3. France: * Regulated Blue Tariff (TRV): this is a fixed tariff regulated by the government, available to households and small businesses, which guarantees some stability against market fluctuations. * Green tariff options: some suppliers offer renewable energy tariffs that guarantee that the electricity supply comes from sources such as wind or solar. 4. Portugal: * Social Electricity Tariff: similar to Spain, Portugal offers subsidized tariffs for vulnerable consumers, with a discount on the bill for low-income households. * Hourly tariffs: these are structured according to the hours of the day, similar to Spain's time discriminatory tariffs, with three periods: peak, flat and off-peak. Energy consumption decisions in Europe are deeply influenced by electricity tariffs, which vary by location, which also impacts the cost-effectiveness of installing solar panels. These differences depend on factors such as the tariff structure, the share of renewable energy and the fiscal and energy policies of each country. As we have already seen, in Spain, the tariff with hourly discrimination allows users to take advantage of off-peak hours to obtain lower prices. This type of tariff encourages the  
Figure 4: Consumption periods from Monday to Friday on working days according to the new electricity bill [18]. Figure 5: Periods of consumption on Saturdays, Sundays and public holidays according to the new electricity bill [18]. installation of photovoltaic systems to maximize savings during sunlight hours. However, the high volatility of tariffs such as the Voluntary Price for Small Consumers (PVPC), linked to the wholesale market, means that consumers must weigh the risks of variable prices against the advantages of solar self-generation.