# Making Optimal Location-Sizing Decisions for Deploying Hybrid Renewable Energy at B&Bs
## 5 Results and Discussion  
### Analysis of the Base Case  
#### 5.1.1 100% Self-Sufficiency in the Base Case  
Table 3 summarizes the optimal solution for the B&B to run its business with 100% solar/wind power. In the solar-only RE system, the B&B would need to install a total of 1161 solar panels at various locations to generate sufficient energy, along with a 125-kWh battery to ensure continuous energy supply. Those solar panels would generate an average 154,977 kWh of electricity in one year. The MIP model measures the annual costs for such an RE system to be USD 25,187. For the solar-wind hybrid RE system, the B&B would need to install a total of 799 solar panels, 17 wind turbines, and a 126-kWh battery. This would produce an average 116,942 kWh of electricity each year at the cost of USD 21,499. Although both systems would allow the B&B to be totally independent of the power grid, their costs are also substantially higher. To be precise, when obtaining electricity only from the power grid, the B&B would need to pay USD 9059 annually (calculated from the data in Figure 12 in Appendix D), which is approximately 36% of the costs required to adopt the solar-only RE system and 42% of those required to adopt the hybrid solar-wind RE system. The results also present that both RE systems are much costlier due to overproduction, especially in the solar-only RE system. It generates more than three times the electricity than the B&B actually needs (50,217 kWh/year). This significant overproduction is due to the time difference in energy generation and consumption as well as the seasonal difference in producing solar energy. A detailed analysis of energy flow in the solar-only RE system is performed to understand how the time difference leads to overproduction. The analysis uses energy flow in the week of July, which is considered a high-demand season for the B&B (Figure 3). The energy flow on Wednesday, the central day of the week, can be described as follows:  
Figure 3: Energy generation, demand, and battery storage in a July week: solar-only scenario. * In the first time period, \(t=9\) and REQ\({}_{9}=23\) kWh, no energy is produced during this period, as \(E_{9}=0\). Therefore, the model allocates all energy saved in the battery during the previous period to satisfy demand, as \(I_{8}=23\) kWh, and \(I_{9}=0\) kWh. * In the second time period, \(t=10\) and REQ\({}_{10}=29\) kWh, the model allocates solar panels to generate much more energy than is required to satisfy all the demand in these periods and to save energy in the battery for later use, as \(E_{10}=253\) kWh and \(I_{10}=113\) kWh. However, some of the energy was unused in this time period, as \(W_{10}=111\) kWh. * In the third time period, \(t=11\) and REQ\({}_{11}=71\) kWh, the model allocates solar panels to produce energy, as \(E_{11}=256\) kWh and the battery to save energy \(I_{11}=95\) kWh. The remaining energy would be unused, as \(W_{11}=204\) kWh. * In the fourth time period, \(t=12\) and REQ\({}_{12}=72\) kWh, no energy was produced during this time period, as \(E_{12}=0\). The model allocates energy saved in the battery from the previous time period to satisfy demand, as \(I_{11}=95\) kWh, and \(I_{12}=23\) kWh. In summary, solar panels would produce energy during daytime hours (i.e., the second and third time periods), but the B&B would consume the most energy during nighttime hours (the third and the fourth time periods). These time differences would allow sufficient surplus power to be saved in the battery to satisfy nighttime demands. Since solar radiance varies significantly from one season to the next, the 1161 solar panels (i.e., a fixed power generation capacity) certainly produce much unused energy at certain times, that is, surplus energy neither used to satisfy demand nor saved in the battery. Interestingly, the volume of unused energy exceeds the demand and occurs primarily during daytime hours. The average volume of unused energy is 10.3% higher on weekdays (Monday-Friday) than on weekends (Saturday-Sunday).