This study focuses on technology and demand forecasts for photovoltaic technologies like c-Si technology and thin film technology. Energy efficiency of both technologies will improve while cost reduction of thin film technology is larger in a long run. On the other hand, customers' preference structure is modeled with attributes including price, capacity, efficiency and lifetime to find which technology customers would prefer in the future by using conjoint model. Along with the improvement on cost and efficiency, the demand of these renewable energy technologies can be forecasted. Competition and market shares of the technologies can be thus simulated. The results show demand forecasts of different competing photovoltaic technologies up to year 2030. In addition, changes of future potential market segment and corresponding customers' characteristics are described and discussed.