*3.4. Simulation, Calculation and Evaluation*

To analyse the grid-side synergy effects between e-mobility and PV potentials, load flow calculations with annual load profiles (15-min mean values) are performed for different scenarios. These scenarios differ between the penetration of EV, the penetration of PV, charging power and charging strategy (controlled and uncontrolled charging). The results from the load flow calculations are analysed with regard to the utilisation of the equipment (e.g., transformer, lines). This is followed by the identification of overloaded equipment, the percentage value, the duration and time of occurrence of these overloads and thus the identification of worst-case weeks. In addition, the influence of PV and EV interactions on these overloads is investigated. Besides the grid-side synergy effects, energy-based analyses are carried out for the same scenarios. For this purpose, the following four key performance indicators are defined: (i) the residual load *PRes*, (ii) the degree of self-generation (DSG), (iii) the degree of self-sufficiency (DSS) and (iv) the self-consumption ratio (SCR). The residual load describes the difference between the power of consumers and e-mobility *PConsumer*+*EV* and the power of the photovoltaic potential *PPV*. If in a certain 15-min time step the PV production exceeds the total load, the residual load becomes negative and vice versa.

$$P\_{\text{Res}} = P\_{\text{Consumer} + EV} - P\_{PV} \tag{1}$$

While the residual load is determined for each 15-min time step of the annual total load profile and the annual PV potential profile, the defined time frame for the determination of DSG, DSS and SCR is defined as one day (96 15-min time steps). The calculation of daily values, in comparison to the determination of an annual value, enables the seasonal consideration of the interaction between the e-mobility and PV potentials.

To explain the DSG, DSS and SCR, Figure 8 shows a generic load profile (consumer and EV) and a generic PV production profile as an example.

**Figure 8.** Relevant areas for calculating the DSG, DSS and SCR.

The degree of self-generation (DSG) describes the locally produced energy in relation to the locally consumed energy for a defined time frame:

$$DSG = \frac{E\_{PV}}{E\_{Consumer+EV}} = \frac{\int\_{t\_{start}}^{t\_{end}} (P\_{PV}(t)) \, dt}{\int\_{t\_{start}}^{t\_{end}} (P\_{Consumer+EV}(t)) \, dt} \tag{2}$$

where *EPV* is the total locally produced energy and *EConsumer*+*EV* is total energy demand for the defined time frame.

The degree of self-sufficiency (DSS) considers the ratio between the directly consumed part of the locally produced energy *ESC* and the total energy demand. This means that this criterion describes the proportion of the total load required that can be covered directly by the PV potential:

$$DSS = \frac{E\_{SC}}{E\_{\text{Consum}r+EV}} = \frac{\int\_{t\_{start}}^{t\_{end}} \left(\min\{P\_{\text{Consum}r+EV}(t), P\_{PV}(t)\}\right) dt}{\int\_{t\_{start}}^{t\_{end}} \left(P\_{\text{Consum}r+EV}(t)\right) dt} \tag{3}$$

The self-consumption ratio (SCR) relates the directly consumed part of the locally produced energy to the total locally produced energy:

$$\text{SCR} = \frac{E\_{\text{SC}}}{E\_{PV}} = \frac{\int\_{t\_{\text{start}}}^{t\_{\text{end}}} \left( \min \{ P\_{\text{Consumer} + EV}(t), \ P\_{PV}(t) \} \right) dt}{\int\_{t\_{\text{start}}}^{t\_{\text{end}}} (P\_{PV}(t)) \, dt} \tag{4}$$
