*2.1. Climatic Data*

The climate raw data used in this article has been obtained from the Meteonorm database [69]. This commercial software provides, for an average climatic year, among other variables: hourly data of pressure, temperature, superficial wind speed and solar irradiation incident on an optimally tilted solar panel.

Meteonorm provides weather data everywhere on the planet by means of the interpolation of registered variables in specific points. However, we have only used those locations where the meteorological stations are placed and are logging the climatic variables directly. With this criterion, 844 locations spread over the whole planet were selected.

With the objective to generalise the results of the application of the methodology, the selected locations have been classified following the Köppen–Geiger climatic regions, which divides the Earth into regions according to their weather conditions [70,71]. Figure 4 shows the location of the meteorological stations used in this study and their correspondence with the Köppen–Geiger regions.

**Figure 4.** Location of the meteorological stations in the Köppen–Geiger climate classification areas. Source: [72] and self-elaboration.

#### *2.2. Solar PV and Wind Generation Patterns*

To estimate the electricity generation, a PV+W hybrid facility prototype has been designed according to the simplified diagram shown in Figure 5.

**Figure 5.** Single line diagram of the photovoltaic+wind hybrid (PV+W hybrid) facility.

The electricity produced by the PV facility placed at the location *x* is calculated with the following expression, adapted from [73]:

$$E\_x^{pv} = G\_{\mathbf{x}'} A\_{PV} \cdot \text{PR} \cdot \eta \cdot [1 + a(T\_x - 293)] \tag{9}$$

where:


Nowadays there are different technologies used in the manufacturing of solar panels; the most widely used is multi-crystalline silicon cells [74]. For the calculation of the electricity generation, it was selected a commercial solar panel manufactured with multi-crystalline silicon cells and an efficiency η of 15.5%. The rest of the solar panel characteristics are shown in Table 5.


**Table 5.** Solar panel characteristics [75].

The PV facilities present current *PR* values in the 60 to 90% range [76,77], therefore, in this study, a mean value of 75% was considered for *PR*.

The area for solar panels was set up in 23.2 m<sup>2</sup> because it is a medium size surface suitable to be placed on every roof, pergola, etc. According to the characteristics of the solar panel selected, this area means 12 solar panels giving a power capacity of 3.6 kW.

For the wind facility, a vertical-axis wind turbine generator (VAWT) was selected. These types of wind turbines are more efficient in locations where the wind stream presents both high turbulence and continuous variations in the direction, such as in the urban environment [33,37,41]. The VAWT considered in the calculations has a nameplate power of 3.5 kW, similar to the PV installed capacity. Figure 6 shows the VAWT power curve for standard density (ρstd = 1.225 kg/cm2).

**Figure 6.** Vertical-axis wind turbine generator (VAWT) power curve for the standard air density ρstd = 1.225 kg/cm2. Source [78].

The electricity produced by the wind facility is calculated according to the following equation (adapted from [79]):

$$E\_x^w = \rho \cdot \frac{P\_x}{\rho\_{std}} \cdot t \tag{10}$$

where:


Finally, the electricity produced by the PV+W hybrid facility is:

$$E\_{\mathbf{x}}^{\text{pv}+\mathbf{w}} = E\_{\mathbf{x}}^{\text{pv}} + E\_{\mathbf{x}}^{\text{w}} \tag{11}$$

The energy produced was calculated for each type of facility (PV, wind and PV+W hybrid) in all locations, obtaining the evolution in an average year with climatic conditions characterised for the variables defined in Chapter 2.1. Figure 7 shows, as an example, the generation curves of the PV, wind and hybrid facilities in an average month of May at one of the locations considered in this study.

**Figure 7.** Time evolution of the generation in May.

One interesting result of this first step of the calculation is the contribution of the electricity sources, PV and wind, to the total hybrid facility production. Table 6 shows the PV Facility contribution to the total generation in the group of different climatic regions. Despite the PV and wind capacity being similar, the contribution of PV is a majority with 84% on average; going from 71% in polar climate zones to 91% in tropical areas. This predominance of PV is justified because the facility locations were not chosen with the criterion of having a relevant wind resource.


**Table 6.** PV contribution to the PV+W hybrid-facility generation. (See Figure 4 for climate zone codification).
