Assessment of the Technical Performance and Investment Economics of the Photovoltaic Rooftop of the BTS Sky Train Station

Abstract

This paper presents assessment of the technical performance assessment and investment economics of the photovoltaic rooftop of the BTS Sky Train Station. The performance assessment using the PVSYST software, found that the performance ratio of the system is 77.2 while the specific energy is 1,380 kWh/kWp. The capture loss and System loss are 0.78 kWh/kWp d and 0.34 kWh/kWp d, respectively. The initial investment cost was 9,444,000 Baht with an electricity purchasing price (Feed in Tariff: FIT) of 6.55 Baht/kWh over the 25 year projected life time and discount rate at 6.875%, which were the criteria for the decision making to constructed the roof. The investment economics were evaluated using measures of Net Present Value (NPV), Internal Rate of Return (IRR), Benefit-Cost ratio (B/C), Discount payback period (DPB) and Cost of Energy (COE). The results show NPV of 3,966,819.10 Baht, IRR 4.46%, B/C 1.34, DPB 8.78 years and COE 2.39 Baht/kWh. However, the IRR was less than the MLR, indicating that the project was not worth the investment. The sensitivity analysis of the project for FIT found that less than 5 baht/kWh, the NPV and IRR were negative. With a system cost of 50 Baht/W, the project would be economically viable, or a positive NPV, IRR, B/C DPB and COE the system cost should not exceed 80 Baht/W. The project also would be feasible if the specific energy production was in the range 1,550-1,600 kWh/kWp with the discount rate not exceeding 10.875%.