การประเมินการลงทุนระบบผลิตไฟฟ้าพลังงานแสงอาทิตย์ บนหลังคาบ้านอยู่อาศัยในภาคเหนือของประเทศไทย

Abstract

The objective of this independent study was to evaluate the investment of solar rooftop for power generation in case of on-grid for business and domestic consumption for energy saving. The electric charge of the net metering system compared to the return on investment of government bonds. The study concentrated on the areas in 20 Meuang Districts of Chiang Mai, Chiang Rai, Mae Hong Son, Lamphun, Lampang, Phayao, Phitsanulok, Uttaradit, Phrae, Kamphaeng Phet, Sukhothai, Tak, Phichit, Nan, Lopburi, Nakhon Sawan, Phetchabun, Sing Buri, Chai Nat and Uthai Thani. The capacities of the solar cell systems in this study were 3,000 watts, 5,000 watts and 10,000 watts. The information data of the solar system investment cost were collected from available websites of contractors and Thailand solar radiation data from the data base of the Department of Alternative Energy Development and Efficiency. The results showed that the average market installation costs including VAT of the rooftop systems sizes for 3,000 watts was 221,490 baht, 5,000 watts was 326,350 baht and 10,000 watts was 631,300 baht. In case of household installation for energy saving, the net metering buyback rate would be compared with the price of electricity of household electricity authority. The price currently was 4.18-4.54 baht/kWh and also depended on the amount of electricity used per month. The electricity price increased every year. The energy cost in this study was assumed to increase by 3% per year throughout 25 years. The solar power system for solar rooftop of 3,000 watts, 5,000 watts and 10,000 watts in Chiang Mai Province showed that payback period were 12.11 years, 10.25 years and 9.51 years. The internal rate of return were 7.6%, 9.5% and 10.5%. The net present value were 12,411.91 baht, 83,830.12 baht and 225,962.55 baht. The benefit cost ratio were 1.054, 1.246 and 1.343, respectively. The study had 4 criteria for determining using financial indicators, which were as follows: PB < 10 years, IRR > 8.38%, NPV > 0 baht and B/C > 1. The study founded that 3,000 watts power system size was not suitable for all investor provinces but 5,000 watts system was more likely to pass the feasibility of the installation and to give a higher return on investment than the investment in government bonds.