# Techno-Economic Analysis of Waste Heat Recovery in Automotive Manufacturing Plants
## 4 Results and Discussion
### System Performance of Photovoltaic  
Figure 4 presents the monthly performance results of the PV system, showing energy output in AC MWh alongside corresponding average solar radiation in kWh/m\({}^{2}\)/day for a full year. The data span from January to December, illustrating variation in radiation and PV energy output; the PV energy output closely follows the solar radiation levels throughout the year. The total energy produced by PV is around 1.35 GWh AC. The peak output is in August, which marks the highest energy output at 145,917 kWh AC, with the highest average solar radiation of 6.42 kWh/m\({}^{2}\)/day. In this case, the lowest output is in December, which records the lowest energy output at 76,427 kWh AC and the lowest solar radiation at 3.34 kWh/m\({}^{2}\)/day. Indonesia's tropical climate brings two main seasons: a dry season (April-September) and a wet season (October-March). The PV system performs optimally in the dry season, when solar radiation increases from April (5.28 kWh/m\({}^{2}\)/day) to September (6.18 kWh/m\({}^{2}\)/day), contributing to high energy outputs. During the wet season, energy output declines due to cloud cover and reduced sunlight hours, indicating solar radiation between 3.34 and 4.95 kWh/m\({}^{2}\)/day.  
The PV system, which is integrated with battery banks and an inverter, is designed to meet the energy needs of a 100-kW heat pump, which operates in a manufacturing plant running 24 h a day for about 20-22 days each month. The PV system harnesses solar energy during the day to power the heat pump while also charging the battery bank. The battery bank is essential for storing surplus energy produced by the PV system. This stored energy ensures that the heat pump can operate reliably at night and during times when solar power is unavailable. Utilising the stored energy allows the heat pump to function continuously, even after sunset, minimising the need for external power sources and providing a consistent energy supply throughout the day and night. Based on the system's performance data, the daily energy produced is generally sufficient to support the heat pump and charge the battery bank (for the operation of the heat pump at night), especially during months with higher solar radiation. In peak months like August, when daily solar radiation reaches 6.42 kWh/m\({}^{2}\), the PV system not only meets the heat pump's demand,  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & \(\eta_{ORC}\) & \(\xi\) & **P2P** \\ \hline MSE (-) & 5.5947 \(\times\) 10\({}^{-5}\) & 0.1121 & 4.0907 \(\times\) 10\({}^{-4}\) \\ RMSE (-) & 0.0075 & 0.3348 & 0.0202 \\ \hline \hline \end{tabular}
\end{table}
Table 5: The MSE and RMSE between the proposed system both with and without a recuperator in the ORC.  
but also generates excess energy. This surplus can be redirected to support other operations in the manufacturing plant, thereby optimising energy use and reducing dependence on external sources. For instance, from May through September, the PV output consistently exceeds the heat pump's requirements, allowing the additional energy to be utilised for other purposes, such as powering auxiliary equipment and supporting additional heating and cooling processes. Even in months with lower radiation, like December and January, the PV system's output remains close to or meets the heat pump's daily energy requirements, ensuring reliable operation year-round.