# Assessment of Air-Pollution Control Policy's Impact on China's PV Power: A System Dynamics Analysis
## 4 Simulation Results and Analysis
### Analysis of Policy Effect  
Based on the simulations, we analyze the impact of air-pollution control policy on China's PV power by drawing curves of the same variable in three scenarios in one graph (see Figures 7-16), and comparing the differences between them. We compared all variables presented in Tables 15-17 except for the investment of distributed PV power and PV plant, because they are not set as policy objectives, and can be reflected in installed capacity. The comparison results of PV power generation and its proportion, distributed PV power generation and PV plant power generation reflect the fulfillment of generation objectives mentioned in air-pollution control policy. The comparison results of PV power curtailment and interregional transmission capacity reflect the fulfillment of power transmission objectives. The comparison results of installed PV capacity, distributed PV installed capacity and PV plant installed capacity reflects the fulfillment of capacity objectives. In addition, the proportion of distributed PV capacity reflects the composition of PV power. In general, these ten variables cover almost all of the evaluate indexes of China's PV power development. Figure 11: Distributed PV power generation (\(10^{8}\) kWh). Figure 10: Interregional transmission capacity (\(10^{8}\) kWh)  
Figure 9: PV power curtailment  
Figure 14: Installed PV capacity (MW). Figure 12: PV plant power generation (\(10^{8}\) kWh). Figure 13: Proportion of distributed PV capacity. The differences between the curves of Scenario 1 and 2 indicate the impact of fundamental air-pollution control policy ('fundamental policy' for short) on China's PV industry. The differences between the curves of Scenario 1 and 3 indicate the impact of both fundamental and supporting air-pollution control policies ('supporting policies' for short). The differences between the curves of Scenario 2 and 3 indicate the impact of only supporting policies. We can tell from Figures 7-16 that:  
(1) Fundamental policy will obviously increase the generation of all clean energies including PV power by limiting emissions. However, the proportion of PV generation in Scenario 2 will eventually drop to nearly the same level in Scenario 1, because of the lack of special supports for PV power. Supporting policies can make PV power generation and its proportion remain stable. However these policies cannot make generation continue increasing, because wind power will still have more mature technology and more competitiveness unless new technological revolutions occur in PV power. (2) Fundamental policy will make PV power curtailment more severe because of the lack of control measures. Supporting policies will firstly aggravate PV power curtailment during 2015-2020 because of the surge of installed PV capacity. While after that supporting policies can reduce the curtailment sharply and eventually eliminate it by accelerating the construction of transmission grid. (3) Fundamental policy can promote the development of China's PV power temporarily, but cannot maintain its growth trend. When China's transmission grid stays immature, the supporting policies will keep PV power generation increasing by promoting distributed PV power, which does not need to be transmitted over distance. However, since 2021, transmission problem will no longer be an important factor to limit power generation of PV plant, and the saturation of architecture resources  
Figure 16: PV plant installed capacity (MW). Figure 15: Distributed PV installed capacity (MW). will become the restriction of distributed PV power. Thus, from that time PV power plant will be the new development priority, and the proportion of distributed PV power will start to drop slightly. (4) Fundamental policy of China's PV power only involves subsidy mechanism and capacity target, but no suitable development planning. Therefore, the development of PV power will run out of steam since 2021.