## 2 Materials and Methods  
### Methodology  
The aim of the present study is to focus on the potential photovoltaic system, integrated on a stadium suspended roof, from a local community point of view. The work starts by analyzing the solar radiation throughout the whole year for the specific site. Therefore, the stadium electric loads and site availability for PV installation were estimated. A monthly energy PV performance analysis was conducted to prove the concept. The PV system is integrated with energy storage. We developed a numerical model to evaluate the energy output from the PV system and how much of this is delivered to the public grid and stored in the static battery. PV system dynamic simulations were conducted through an open-source software tool known as the System Advisor Model 2023.12.17 (SAM) [28]. The SAM was developed by the National Renewable Energy Laboratory (NREL) in collaboration with Sandia National Laboratories and the U.S. Department of Energy (U.S. DOE) Solar Energy Technologies Program. The SAM provides a robust platform for analyzing and modeling the performance of renewable energy projects. It supports a wide range of technologies, including solar, wind, and geothermal systems. The simulation is carried out in hourly steps since this is also the given resolution of the generation and load profiles. It was estimated the equivalent energy generated by the PV system and fed into the public grid able to supply enough energy for local household utilities and public lighting. The flowchart of the methodological approach is shown in Figure 1.  
The economic performance of the solar PV system is assessed using key economic parameters, including payback period (PP), net present value (NPV), and internal rate of return (IRR). The initial investment cost is calculated from kW cost of the PV system. According to the renewable energy market analysis, reported in 2021 by the International Renewable Energy Agency (IRENA) [29], the rooftop PV and the battery energy storage systems were implemented in 2021 at 724.5 EUR/kW and 1020.7 EUR/kWh, respectively. The initial cost refers to the cost of the system components and implementation. The operation and maintenance costs amount to 9.2 EUR/kWh. The initial investment and operating costs are regarded as the cost outflows of the designed system. Cash inflows are determined by the cost of energy that satisfies the load demand and the revenue generated from energy exported to the utility grid. The cost of electricity is taken according to ARERA the Regulatory Authority for Energy, Networks and the Environment [30]. It publishes an update on the economic conditions of protection services quarterly for electricity. This price ranged from 0.44 EUR/kWhe (if the electricity is acquired from the national grid) to 0.11 EUR/kWhe (in case the electricity is sold and delivered to the national grid). The project lifetime is 25 years, which is the same as the replacement time for the PV panel [31].  
Finally, the CO\({}_{2}\) emission reductions were investigated considering the value (258.3 gCO\({}_{2}\)-eq/kWhe) as the CO\({}_{2}\) emission factor for electricity energy reported by the ISPRA Report 2021 [29].