# Optimal Design of a Residential Photovoltaic Renewable System in South Korea
## 3 Application of the Residential PV System
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Appliance** & \
\begin{tabular}{c} **Power Consumption (W)** \\ \end{tabular} &
\begin{tabular}{c} **Daily Usage** \\ **Hours (hr)** \\ \end{tabular} \\ \hline Fluorescent Tube (20 W) & 20 & 7.9 \\ Fluorescent Tube (32 W) & 32.09 & 7.9 \\ Fluorescent Tube (40 W) & 40.18 & 7.9 \\ Fluorescent (Compact) & 37.90 & 8.1 \\ Fluorescent (Circular) & 39.85 & 5.6 \\ Fluorescent (Stand-Alone) & 25.86 & 7.9 \\ Incandescent & 71.48 & 1.7 \\ Halogen & 94.17 & 1.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Power consumption of lighting appliances. If we aggregate the above-mentioned four types of consumption, we can obtain a monthly power consumption graph, as shown in Figure 2. Here, it should be noted that a consumption amount of 2.2 kWh/day for any additional appliance was added to each monthly amount. So far, the monthly power consumption of a typical Korean house has been assessed based on four different types of consumption. Now let us assess the monthly power generation amount from the PV system (\(PV_{Electric}^{m}\)). The monthly PV generation amount is affected by two major decision variables (PV angle, \(A^{PV}\), and PV size, \(S^{PV}\)). The first affecting factor is the tilted angle of the PV panel, as shown in Figure 3. As seen in the figure, the lowest angle (15\({}^{\circ}\)) generates the highest amount in June, while the highest angle (60\({}^{\circ}\)) generates the highest amount in December. The highest amounts in March and September occur in the middle. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Appliance** & **Average Stand-By Power (W)** & **Daily Stand-By Power Amount (Wh)** \\ \hline Two TV sets & 8.6 & 147.1 \\ Audio System & 9.1 & 191.1 \\ DVD & 12.2 & 269.6 \\ Microwave & 2.8 & 66.2 \\ Air Conditioner & 2.8 & 54.2 \\ Personal Computer & 3.2 & 63.4 \\ Computer Monitor & 2.6 & 51.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Consumption amount of stand-by power. Figure 2: Monthly power consumption for a typical Korean house. For this study, in order to estimate the energy production of the residential PV system, the PVWatts calculator [9], which was developed by the National Renewable Energy Laboratory (NREL) in the U.S. Department of Energy, was utilized. After inputting various PV system specifications such as the DC system size (unit size (1 kW) in this study), array type (fixed in this study), array azimuth (180\({}^{\circ}\) (full south) in this study), system losses (14% in this study), inverter efficiency (96% in this study), and PV tilt angle (\(A^{PV}\)) into the software, we could obtain an estimation of the month-average solar radiation (kWh/m\({}^{2}\)/day), and the monthly unit-size PV generation amount (kWh) for a specific location. For the specific location, this study selected Seoul, the capital city of South Korea. However, PVWatts provided the PV generation data of Incheon, as the nearest location from Seoul (24 miles west from the center of Seoul), whose latitude is 37.48\({}^{\circ}\) N and longitude is 126.55\({}^{\circ}\) E, as shown in Figure 4.  
Figure 3: Monthly photovoltaics (PV) generation amounts with different tilt angles. The influencing factor, PV size (\(S^{PV}\)), can be multiplied by the unit-size generation amount (kWh/kW) at a certain PV angle (\(A^{PV}\)), to calculate the monthly PV generation amount (\(PV^{m}_{Electric}\)). The PV-related construction cost (\(C_{Cst}\)) in Equation (1) is the function of PV size (\(S^{PV}\)). The original PV construction cost is 7,210,000 KRW/kW in this study. However, after considering the Korean government's subsidy (60% of the original cost = 4,326,000 KRW/kW) and the building materials cost savings ($462,500/kW), the PV-related construction cost (\(C_{Cst}\)) becomes 2,421,500 KRW/kW (=7,210,000 - 4,326,000 - 462,500) multiplied by the PV size (\(S^{PV}\)). The PV-related annual maintenance cost (\(C_{Mtn}\)) in Equation (1) is 12,105.7 KRW/kW (0.5% unit \(C_{Cst}\)) multiplied by the PV size (\(S^{PV}\)).