Thailand possesses high potential for solar energy, which has been given more attention from both government and the private sector lately. While the major investment in solar energy has gradually shifted from governments to private sectors, this paper aims to compare private investment's net present value (NPV) and production risks of grid-connected photovoltaic (PV) projects. The scope of this paper includes PV projects on three different scales: 3 kW, 5 MW and 73 MW installed capacity in 74 locations across Thailand. The study utilizes RETscreen software to estimate means and variability in electricity productions in Thailand. Cost-benefit analysis is the method used to measure projects’ NPV and profitability, while portfolio theory is applied to capture the profit variability or production risk. The analysis also includes 3 feed-in-tariff (FIT or adder) scenarios that are likely to happen in the solar energy policy in Thailand; which are 8 baht/kWh, 6.5 baht/kWh and the case where there is no support at all. The study finds that 3 kW PV projects yield negative NPV, which means investment losses, in all scenarios and locations in the country. On the other hand, 5 MW PV projects result in positive NPV in all scenarios and locations and it is concluded to be the most profitable scale among three. 73 MW PV projects are considered as policy dependenceas the projectsyield negative NPV without the supports. Sensitivity analysis shows that the costs of 3 kW projects have to reduce at least by 60% in order to turn the projects to profits. With respect to allocation of risk, the production risks of 73 MW projects are slightly higher compared to the other two scales. Also, it is shown that the technologies located in north of Thailand have higher production risks, but yield approximately the same expected net benefits as technologies located in the rest of the country. As for conclusions, the future of PV technology in Thailand is still bright, but the investors should intensely consider about scale and location of the implementation. Further researches can examine other scales of PV technology and the drives behind the risk characteristics in Thailand.