# A Comparison of Households' Energy Balance in Residential Smart Grid Pilots in the Netherlands
## 3 Results
### Peak Load, Feed-in and Simultaneity  
Figure 5 shows the distribution of the power peaks measured for individual households at a time resolution of 15 min and of the normalized peak for the whole community. The latter is the aggregated peak divided by the number of households. JEM-Easy street was not plotted, as few peaks appeared, and PV generation data were absent. Between the pilots analyzed, the peak imported electricity ranged between \(\sim\)2 kW and \(\sim\)9 kW for all pilots, with four outliers present above 9 kW.  
By looking at an aggregated level, we see an important discrepancy between the households with and without heat pumps. The average peak per household is only around 1 kW for pilots without heat pumps, which is in line with how transformers are generally dimensioned [52]. If we define the simultaneity of electricity as the ratio between the normalized aggregated peak and the average individual peaks, then we observe a very low import simultaneity in the R4I pilot of only 23.0%. This is beneficial from a system perspective, as this low import simultaneity decreases the total capacity requirement. The same holds for Zonnedael, with a simultaneity of 20.5%. However, the simultaneity in the pilots with heat pumps is much higher: 65.1% for JEM and 70.5% for PMC. This can be explained by the fact that heat pumps' electricity demands are strongly correlated with outside temperatures,  
Figure 4: Boxplots of annually imported electricity from the grid and surplus PV (feed-in) to the grid for (**a**) household without heat pumps and (**b**) households with heat pumps. For each box, the red line indicates the median, and the bottom and top edges of the box indicate the 25 th and 75 th percentiles, respectively. The whiskers extend to the most extreme data points without considering the outliers, and the outliers are plotted individually in red.  
which are the same for all households within a community. While, on average, the electricity demand of households with heat pumps is just around 200 Watts higher than that of households without heat pumps, the community peak exceeds 3 kW on top of the baseline. This causes a stress in the LV grid and its transformers. Therefore, it is important to take this into account when designing future LV grids with a high penetration of heat pumps.  
Not surprisingly, the simultaneity of the PV feed-in is also very high: 74.9% for the R4I pilot and 89.5% for JEM (very similar to Zonnedael 88.9%). This calculation was not applicable for PMC, where the virtual PV was controlled by the DSO and distributed to households with PowerMatcher influence, since we noticed that not all households received the same amount of electricity. It is important to mention that, in the investigated pilots, these results show a low potential to cause grid issues: all aggregated feed-in peaks are lower than the aggregated import peaks. Furthermore, feed-in peaks are not as crucial as import peaks, as it is easier to curtail feed-in [32].  
From the investigated connections, only four households may present a possible risk for overloading (i.e., those with a \(1\times 40\) A connection). We do note, however, that this connection is applied only for small houses on special request. For the standard house connection, there were no households who exceeded those levels.