This research presents the study on carbon dioxide emission reduction from large scale photovoltaic (PV) power plant in Thailand using a method based on Annex 14 Methodological Tool (Version 02) “Tool to calculate the emission factor for an electricity system”. The calculation result is coefficient of green house gas emission factor (Combined Margin Emission Factor) for solar electricity generation is 0.5980 tCO2/MWh. Besides that the study on economic analysis of large scale PV power plant in Thailand, with interest rate at 6.75%, benefit from selling CO2 in 7 years shows that net present value (NPV) is 2,472,187,645 Baht, benefit cost ratio (BCR) at 12.52, economic internal rate of return (EIRR) is 20.01%, cost of energy (COE) is 7.96 Baht/kWh and payback period less than 5 years. The sensitivity analysis also presented in this research. Considering the degradable PV efficiency and initial cost have positive economic indicator results. However, adder cost at 6.5 Baht/kWh and interest rate at 10% and 15% make negative economic indicator results. Also considering the different of energy yield at 1,400kWh/kWp found that internal rate of return is 6.66% which is less than interest rate at 6.75. Thus, all PV entrepreneurs are agreeing for bright and growing future of PV industrial business in Thailand.