# Optimal Design of a Hybrid Solar PV/BG-Powered Heterogeneous Network
## 5 Performance Analysis
### Energy Issue  
The annual energy consumed (DC and AC load), surplus energy, and shared energy for the different networks with a 10 MHz bandwidth are summarized in Table 3.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline
**BW** & \multicolumn{4}{c}{**PV (\&\&\&W)**} & \multicolumn{4}{c}{**BG (\&\&W)**} & \multicolumn{4}{c}{**Battery (units)**} & \multicolumn{4}{c}{**Converter (\&W)**} \\ \cline{2-13}
**(MHz)** & **Macro** & **Micro** & **Pico** & **Femto** & **Macro** & **Micro** & **Pico** & **Femto** & **Macro** & **Micro** & **Pico** & **Femto** & **Macro** & **Micro** & **Pico** & **Femto** \\ \hline
5 & 3 & 2 & 2.5 & 2.5 & 1 & 1 & * & * & 32 & 24 & 8 & 8 & 1.5 & 1.5 & 1.5 & 1.5 \\
10 & 3 & 2.5 & 2.5 & 2.5 & 1 & 1 & * & * & 32 & 24 & 8 & 8 & 1  
The monthly statistics of power contribution by the different supply systems are presented in Figures 6-9 for the macro-, micro-, pico-, and femto-base stations, respectively. Those figures were obtained using data considering the dynamic profile of renewable energy sources with an average solar intensity of 4.59 kWh/m\({}^{2}\)/day and a 10 MHz system bandwidth. In line with our expectations, ideal renewables such as solar photovoltaics contribute more energy throughout the year. However, owing to the effective utilization of renewable energy, the biomass generator delivers less energy. It is also seen that no electrical grid energy was utilized for the maximal use of renewables. The fundamental purpose of the electric grid system is to sell the extra energy from renewables and to receive energy back in the event of a shortage or failure of renewable energy and storage system. The introduced system can decrease capital cost and carbon emissions since, under all situations, solar PV provides the most energy. A comprehensive comparison of the yearly energy breakdown by the hybrid supply system under different system bandwidths are shown in Figures 10-13, for macro-, micro-, pico-, and femto-base stations, respectively. The following are detailed energy calculations for the 10 MHz system bandwidth from the solar PV panels, and biomass generators. Figure 8: Monthly power contribution for pico-BS under 10 MHz system BW. Figure 10: Individual energy breakdown for macro-BS. Figure 9: Monthly power contribution for femto-BS under 10 MHz system BW. **Solar PV:** As referred to in Table 2, the optimum size of the solar PV panel is 3 kW for the macro-BS system under a 10 MHz bandwidth. The year-round energy produced through the solar PV module can be approximated using (1): 3 kW \(\times\) 4.59 \(\times\) 0.9 \(\times\) 365 days/year = 4523.44 kWh. Furthermore, due to the two-axis tracking mode, this value will be 6486 kWh. **Biomass Generator:** The optimal size of the biomass generator is 1 kW. The running hours of the BG are 5342 h per year (14.632 h per day) and the used up bio-feedstock is 3.46 tones/year as obtained from HOMER simulation under macro-BS. Therefore, the  
Figure 11: Individual energy breakdown for micro-BS. Figure 12: Individual energy breakdown for pico-BS. Figure 13: Individual energy breakdown for femto-BS. annual generated power is calculated using (2) as follows: \(P_{BG}\) = (3.46 tones/year (\(T_{BM}\)) \(\times\) 3411.33 Kcal/kg (\(CV_{BM}\)) \(\times\) 0.30 (h\({}_{BC}\)) \(\times\) 1000)/(365 \(\times\) 860 \(\times\) 14.632 h (\(t_{op}\)) = 0.770 kW. In contrast, the generated energy is assessed using (3) as follows: \(E_{\rm BG}\) = 0.770 kW (\(P_{BG}\)) \(\times\) 365 \(\times\) 24 \(\times\) 0.50 (capacity factor) = 3416 kWh/year for macro-BS, under 10 MHz bandwidth. In a similar procedure, the year-on-year energy produced by the other system configurations is computed. The fuel of the biomass generators is organic feedstock. The amount of energy harvested from the solar PV/BG system is linearly related to the amount of bio-feedstock consumption and base station energy demand.