# Energy Communities Design Optimization in the Italian Framework
## 4 Results  
### Optimal Design Results  
The optimized selection of the energy conversion and storage systems to be installed in the condominium, to satisfy the energy needs of the users in the four cases, are reported in Table 6. To the aforementioned four cases (A-SSP, A-EC, B-SSP, and B-EC), two further cases have been added for the EC configuration, which feature the optimization of the units assuming there is no bound on the area available for the installation of the PV panels, which make them not practically feasible, though interesting from a speculative perspective. Table 6 reports also the results obtained by the objective function of the optimization model as TAC = OPEX + CAPEX; that is, total annualized costs = operating expenditures + annualized capital expenditures (for which it has been assumed a discount rate = 1% and lifetime of the investments = 20 years for PV and TES, 15 years for boiler and HP) in the considered cases. Values are normalized with respect to the TAC obtained in case A-SSP, which is the highest. Such results show the logic implemented by the optimization model: an increase of the CAPEX, due to the installation of better performing equipment, entails a sensible reduction of the OPEX, which finally leads to an overall reduction of the total annual costs. Such results become even better when the collective self-consumption scheme is adopted. Table 7 reports the natural gas, electricity, CO\({}_{2}\), and economic yearly balances. The electricity balance is expressed by condominium overall electricity consumption, production, import, and export; the electricity section features an outlook of the condominium self \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Case**} & \multirow{2}{*}{**Configurations**} & **HP** & **BOILER** & **PV** & **TANK** & **TAC** & **OPEX** & **CAPEX** \\  & [**kW\({}_{\text{th}}\)**]** & [**kW\({}_{\text{th}}\)**]** & **[**m\({}^{2}\)**]** & **[**kW\({}_{\text{th}}\)**]** & **[**m\({}^{3}\)**]** & **[**p.u.]** & **[**p.u.]** & **[**p.u.]** \\ \hline \multirow{3}{*}{**A**} & **SSP** & n.a. & 77 & 2.50 & 0.38 & n.a. & 1 & 0.96 & 0.04 \\  & **EC** & n.a. & 77 & 100 & 15.00 & n.a. & 0.91 & 0.78 & 0.13 \\  & **EC** & n.a. & 77 & 137 & 20.55 & n.a. & 0.90 & 0.74 & 0.16 \\ \hline \multirow{3}{*}{**B**} & **B-SSP** & 32.0 & 0 & 94.9 & 14.24 & 2.46 & 0.85 & 0.64 & 0.21 \\  & **B-EC** & 31.7 & 0 & 100 & 15.00 & 2.50 & 0.83 & 0.62 & 0.21 \\ \cline{1-1}  & **EC-ideal** & 28.4 & 0 & 244 & 36.60 & 3.75 & 0.80 & 0.47 & 0.34 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Sizes of installed energy systems for each scenario and configuration. consumption, expressed in terms of physical self-consumption (i.e., the amount of energy produced and consumed by the condomium POD) and collective self-consumption (i.e., the amount of energy injected by the condominium POD and consumed by the apartments' POD in the same hour). Values are expressed as a difference with respect to the reference scenario (wherein no electrification investment is made), except for self-consumption percentages, which refer to electricity production. Combining the values reported in Tables 6 and 7, it is possible to notice the potential economic and environmental benefits coming from the implementation of the EC configuration, which makes the investment in renewable energy sources, in this case PV, more attractive than the SSP configuration. Considering Scenario A, the possibility of sharing the RES production in the EC configuration leads to the utilization of all the available surfaces for the installation of PV (100 m\({}^{2}\)), whereas the SSP configuration features a very limited installed PV surface (2.5 m\({}^{2}\)), strictly limited by the low capability of the condomium POD to self-consume the RES production.