Techno-Financial Analysis of Grid Tied Solar Rooftop System A Case Study on Star Homes, Sitapaila, Nepal

Abstract

Most of the national energy demand is from the residential sector in Nepal. Thus, solar PV systems could be an attractive alternative for fulfilling the energy hungry residential sector converting each house as a power source. The objective of this thesis is to analyze the case to supply the required energy from the same demand point via the solar PV installed in the rooftop that is technically feasible. The survey is conveyed on the 20 out of 51 houses in Star Homes (Residential Sector) situated at 27°42'29.35"N latitude and 85°16'49.56"E longitude of Sitapaila, Kathmandu. There are three types of houses type 1, type 2 and type 3 categorized in this study according to their rooftop area and the load consumption pattern. The solar potential has been found to be 3.9 kWp, 4.8 kWp and 7.8 kWp in type 1, type 2 and type 3 houses respectively. Thus, the total solar potential of the Star Homes was found to be 252.8 kWp. For the comparative analysis in this thesis, the isolated PV system is designed/analyzed using PV-SYST and the grid tied PV including/excluding battery is designed/analyzed using SAM (System Advisory Model) software for three types of houses. According to the house type, there is maximum load of 1665 W, 2350 W and 4175 W for type 1,type 2 and type 3 house repectively. According to the load profile, the size of solar standalone system for type 1, type 2 and type 3 house is calculated to be 1620 Wp 26V/ 322Ah, 3240 Wp 51V/302 Ah and 6480 Wp 77V/412 Ah respectively. In standalone system, PVSYST simulation results show the designed system is capable to match the load of type 1, type 2 and type 3 with annual generation of 3067 kWh, 6300 kWh and 9592 kWh respectively and excess annual energy 795 kWh, 1744 kWh and 1429 kWh respectively. The LCOE considering 25 years life time with 7.5 % loan interest for 15 years for type 1, type 2 and type 3 is 0.21$, 0.21$ and 0.22$ per kWh. The designed system of grid tied PV for type 1, type 2 and type 3 are 3.9 kWp, 4.8 kWp and 7.8 kWp respectively utilizing the available rooftop space. The SAM simulation results show the designed system is capable of annual generation of 6483 kWh, 7812 kWh and 12781 kWh respectively and the designed system is able to export energy 5645.45 kWh, 6680.83 kWh and 11277.03 kWh respectively. The net savings of electricity bill after installation of the system for type 1, type 2 and type 3 house is 516$, 635$ and 1018$ respectively. The LCOE considering 25 years life period with net metering and excess energy charged at 0.073$ for type 1, type 2 and type 3 are 0.0703$, 0.073$ and 0.0689$