## 2 Materials and Methods  
### Selection of Photovoltaic-System Combinations  
It is expected that the solar inverter plays a key role for EMEs in PV systems; especially, the choice of topology and solar inverter concept are of importance. EMEs are caused by the switching of the solar inverter, which contains filters to suppress EMEs [3]. Therefore, the following comparisons were discussed: transformer inverter versus transformerless inverter and string inverter versus inverter with module-level power optimizers. The comparison between transformer inverters and transformerless inverters was excluded since no new products with transformers were purchasable in the required power range.  
Figure 1 shows the three variations in solar inverter concept for the comparison of string inverter versus inverter with module-level power optimizers: (a) the string inverter (F, K, S); (b) the inverter with one module power level optimizer per PV module, further called inverter with module optimizers (SE); and (c) the string inverter with one module-level power optimizer on one PV module, further called string inverter with one optimizer (Tx).  
PV modules are seen as passive components and therefore not included in any of the abovementioned studies in connection with EMEs from PV systems. During the discussions of the selection process, the possibility was raised that the leakage current of the PV module could influence the EMEs. Hereby, the frame and the different encapsulations were suspected as possible reasons for changes in the EMEs. Hence, a comparison was made between an aluminum-framed, monofacial, monocrystalline half-cell module with glass-backsheet encapsulation (MO) and a frameless, bifacial, monocrystalline full-cell module with glass-glass encapsulation (BI). This comparison was made to include the potential impact of the leakage current.  
In the installation details, the approach was to compare best practice versus other common installations that are currently not recommended, from an EMC perspective. For the cable management, the loop area behind the PV array was either small-loop (SLS) or large-loop (LL). The string cables in the cable tray had either zero (R) or 10 cm (R10) distance between DC+ and DC\(-\). The earthing was either installed with functional equipotential earthing (W) or without functional equipotential earthing (N).  
For the case without functional equipotential earthing, the vertical equipotential bonding between the aluminum rails and the cable tray bonding were removed. The earthing clips were kept in place even without functional equipotential earthing, since removing them would have created additional time-consuming work, and some PV module clamps on the market provide integrated grounding pins, e.g., Schletter and Solar Parts Components. Therefore, we did not expect this to have a significant impact on the results.  
All abbreviations for components and installation details are listed in Table 1.  
Figure 1: PV system with modules and (**a**) string inverter, (**b**) inverter with one module-level power optimizer per module, further called inverter with module optimizers; (**c**) string inverter with one module-level power optimizer, further called string inverter with one optimizer; and (**d**) notation scheme for PV system combinations.