Distributed solar energy applications in commercial buildings across China: value comparison and policy implication

China is experiencing rapid economic growth and urbanization. In China's continuously growing urban areas, solar photovoltaic (PV) application in buildings is one of the most suitable renewable energy resources. Building PV systems can be categorized into two types: building attached PV (BAPV) and building integrated PV (BIPV). However, in China, there is a lack of research comparing the two systems, especially from the economic perspective. Meanwhile, policy changes play an important role in the economic benefit of building PV projects in China. Among them, changes in national subsidy and electricity price are of great importance for distributed building PVs with high self-consumption ratio. A better understanding of the impacts of these policy-related factors on the economic performance of building PVs is required. Additionally, China is a large country with diverse geographic conditions and policy conditions. The complexities of the regional situation make it difficult for investors and policy-makers to have a clear understanding of actual value of building PV systems, which hinders the uptake of both BAPV and BIPV in China. <br><br>This research aims to address these research gaps. Through the literature review, the most popular building PV applications in China are identified. Hence, five building PV scenarios are developed based on real-word cases, including BAPV, roof BIPV and window BIPV. Given the diverse geographic conditions and policy conditions in China, 12 typical cities are selected for the research. A MATLAB program is established to calculate energy generation and evaluate the economic performance of the building PV applications in the 12 cities. By changing the input of the national subsidy and tariff growth rate in the program, the impacts of the two policy-related parameters on the economic results are investigated. The impact of shading loss in the urban environment is also incorporated.<br><br>The results show that, under current geographic conditions and local policy, roof BIPV replacing glazing roof is the most attractive investment option for investors among all building PV types. In terms of cities, Shanghai is the first option for both BAPV and BIPV investment, while cities including Guangzhou, Chengdu, Guiyang and Chongqing are less financially attractive to investors. The findings can improve the investment confidence of building PVs in China, especially for BIPVs. <br><br>For the national subsidy, the results can be categorized based on economic performance and sensitivity to the subsidy. For different stakeholders, different implications are generated based on economic performance and sensitivity. Generally, Shanghai, Taiyuan and Tianjin are believed to be the best investment destinations of building PVs among the 12 cities at the risk of shrinking subsidy. Policy-makers can reduce national subsidy in the cities categorized as having good economic performance, while seeking other incentives to stimulate the economic performance for PV scenarios and cities with bad economic performance and low sensitivity.<br><br>Regarding the impact of tariff growth rate, the results show that the outlook on the future electricity price can significantly affect the economic performance of building PV applications in the cities with high sensitivity to electricity price change. Thus, building PV applications can be promoted in the cities with high potential of the electricity price growth. On the other hand, there are cities that make building PV application a safe and profitable investment, such as Shanghai and Taiyuan.<br><br>Moreover, the shading loss analysis shows that roof BAPV with large capacity and roof BIPV replacing glazing roof are still recommended for investment. In terms of city, Shanghai remains the first option for all kinds of building PV investment. By contrast, more attention should be paid in Chengdu, Chongqing and Urumqi to confronting the increasing city density. <br>The contributions of this research are to: (1) improve investors¿ and policy-makers¿ understanding of the value of PV buildings across China; (2) provide policy implications to encourage the healthy growth of the building PV applications in China; and (3) demonstrate feasibility of building PV systems for other cities in similar climates and/or for cities in developing countries like China.