# Exploring the Benefits of Photovoltaic Non-Optimal Orientations in Buildings
## 2 Materials and Methods
### Case Study #1: Residential PVSCS
#### 2.2.3 Residential Tariffs in Spain  
Before performing the economic evaluation, the residential tariffs for electricity in Spain need to be looked at. These tariffs are composed of three parts: a part based on the nominal contracted power (named access charge), a variable part for the energy consumed (energy charge), and taxes (a 5.11% of electricity tax and 21% VAT, resulting in a total of 27.50%). The final price of the electricity for the consumer depends on the electricity marketer company and the consumer can freely choose among a variety of commercial offers in the free market and in the regulated marked.  
The electricity tariffs not only support the costs of the production, transport, and distribution of the electricity. The costs of producing electricity exhibit in the wholesale electricity market prices. In Spain, the overall costs of the electrical system are called tolls and charges. Tolls include the electricity transport and distribution costs and are established by the National Commission for Markets and Competition (CNMC). Charges are a concept, including other costs such as renewable energy retribution (mainly the FiT for wind and solar power generation, overcharges of the Balearic and Canary Island electrical systems, tariff deficit, and other costs). The charges are established by the national government. Part of these costs are included in the access charge and part in the energy charge. For residential tariffs, there are no other charges, such as reactive power and maximum demand penalties. The maximum power demanded for these consumers is controlled by the ICP, which is a switch that turns off the electricity supply if the maximum contracted power is exceeded in a 15-min period. So, the installation of a self-consumption system does not allow a reduction in the contracted power for the residential case. A more comprehensive description of the Spanish tariffs is available in [44].  
Formerly, there were three main residential tariffs of choice in the regulated market or PVPC (voluntary price for the small consumer).  
* Time constant tariff: the price of electricity is indexed to the pool market by a fixed toll that includes part of the electrical system costs and is added to the hourly pool market price and other costs, including commercial profit.
* Two-period tariffs: the price of electricity is indexed to the pool market, but the toll has two different values depending on the hour of the day. There were the former 2.0 DHA and the 2.0 VE for electric vehicles.  
New tariffs in Spain became effective in June 2021. The new residential tariff 2.0 TD is a three pricing period structure that replaces all the 2.x tariffs [44] (see Table 1). This regulatory change establishes higher prices on periods of higher consumption to promote demand shift management habits in the customers. In Figure 4, the demand profiles for the whole Spanish electrical system in representative days of winter and spring are plotted, and the selection of peak periods in accordance with the two periods of maximum electricity demand in the Spanish electrical system are clear.  
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