## 4 Results and Discussion
### Results
#### 4.1.2 Comparison of Economic Performance: Low and High Usage of Kindergarten
However, in certain cases where the values remain identical across different reconciliation periods or schemes, this outcome occurs because the PV system generates sufficient surplus energy to cover the building's demand. At the end of the reconciliation period, any remaining credits ensure that grid electricity is not required, resulting in the same LCC, WLC, and payback periods across those conditions. The LCOE is a key indicator for assessing the economic viability of the PV systems [62] implemented in the kindergarten's energy upgrade. The results in Table 11 represent the average cost of electricity generated over the lifetime of the PV system, considering the installation, operational, and maintenance expenses. The LCOE values for all scenarios demonstrate the economic feasibility and competitiveness of the PV system installation. For comparison, the Fraunhofer Institute for Solar Energy Systems) reported that, as of 2021, the LCOE for PV systems in Germany ranged from EUR 0.0312 to EUR 0.1101 per kWh, depending on system size and location [63]. The kindergarten's LCOE values fall well within this range, confirming the financial viability of the energy upgrade. The low-usage scenario achieves the lowest LCOE due to reduced energy demand, which allows the PV system to meet a larger share of the building's needs while exporting surplus energy to the grid. In the high-usage scenario with a larger PV system, the LCOE remains financially viable, showing a 9.1% increase compared to the low-usage case, driven by higher energy demand and greater reliance on grid electricity. However, in the high-usage scenario with a smaller PV system, the LCOE rises further, reflecting a 16.9% increase compared to the low-usage scenario and a 7.1% increase relative to the high-usage case with the larger PV system. This increase highlights the impact of reduced PV capacity, which limits energy production and spreads fixed costs over a smaller output. Figure 8 from the ROI analysis reveals that net metering consistently outperforms net billing across all usage cases, particularly under favorable conditions like yearly reconciliation, where surplus energy offsets cost on a 1:1 basis. In contrast, net billing undervalues exported energy, leading to comparatively lower returns. Yearly reconciliation achieves the highest ROI for both policies by aggregating surplus energy over an extended period, significantly reducing costs. However, as reconciliation intervals shorten to quarterly, monthly, or daily, ROI declines due to surplus energy being penalized or unused, which diminishes its cost-saving potential. For instance, in the High Usage scenario under net metering, ROI decreases from 2.29 (yearly) to 1.89 (daily), marking a 17.4% drop. When it comes to maximizing the financial benefits of the investment, the analysis also highlights the importance of appropriately selecting the PV system size under the constraint of covering the building's energy needs. As observed in the High Usage Low PV case, the payback \begin{table}
\begin{tabular}{c c} \hline
**Scenarios** & **LCOE (EUR/kWh)** \\ \hline High Usage & 0.0885 \\ Low Usage & 0.0811 \\ High Usage (Small PV) & 0.0948 \\ \hline \end{tabular}
\end{table} 
Table 11: Levelized Cost of Electricity Results. period is 6.01 years (yearly), and ROI is significantly higher compared to the full High Usage scenario, underscoring the importance of appropriately sized PV systems to optimize cost-effectiveness and ensure balanced economic outcomes.