『Abstract
　Solar energy utilization can not only decrease conventional energy consumption but also reduce environmental pollution. China has abundant solar energy resources and has the biggest solar water heater market in the world, so it is necessary for Chinese government to enact incentive policies and measures to enlarge the utilization scale of solar water heaters. According to international experience, solar obligation is probably the most powerful instrument for promoting the use of solar thermal in buildings and expanding the solar water heater market. Currently, there are many provinces and cities in China having adopted the solar obligation, leading to the discussion of solar obligation at national level. This paper firstly analyzed basic conditions to implement the solar obligations in China. Then, 34 provinces and cities' local regulations were reviewed and main problems of them were analyzed. According to domestic and international practices, some recommendations for the design and implementation of solar obligations at national level were induced at the end.

Keywords: Solar obligation; Solar water heater; China』

Contents
1. Introduction
2. Basic conditions for the implementation of solar obligations in China
　2.1. Solar energy resources in China
　2.2. SWH industry in China
　2.3. Existing renewable energy policies in China
　2.4. Existing technical standards and quality certification system
3. Local regulations including solar obligations in China
4. Problems and recommendations for solar obligations at national level
　4.1. Contents of the solar obligation
　4.2. Enforcement procedures and sanctions
　4.3. Quality assurance system
　4.4. Support measures for solar obligations
　4.5. Technical standard system
5. Conclusion
Acknowledgements
References

Fig. 1. The SWH enterprise share of different province and city at the end of 2009 Table 1 Four zones of solar radiation in China Zone No. Solar availability Annual irradiation (MJ/m2) Annual sunlight (h) Region Percent of soil area (%) I Very abundant >6700 3200-3300 Most of Tibet, south of Xinjiang, west of Inner Mongolia, west of Gansu, west of Qinghai 17.4 II Abundant 5400-6700 3000-3200 Most of Xinjiang, east of Gansu, east of Qinghai, Ningxia, Shanxi, Shaanxi, Hebei, Beijing, Tianjin, northeast of Shandong, east of Inner Mongolia, Yunnan, west of Sichuan 42.7 III Available 4200-5400 1400-3000 Heilongjiang, Jilin, Liaoning, Anhui, Jiangxi, south of Shaanxi, Shandong, Henan, Zhejiang, Jiangsu, Hubei, Hunan, Fujian, Guangdong, Guangxi, Shanghai, Hainan, south of Guizhou 36.3 IV Poor <4200 1000-1400 Sichuan, Guizhou, Chongqing 3.6 Table 2 The holding accumulative total and annual yield of SWH from 1998 to 2009 Year Annual yield (104 m2) Annual growth of yield (%) Holding accumulative total (104 m2) Annual growth of holding (%) 1998 350 - 1500 - 1999 500 43 2000 33 2000 640 28 2600 30 2001 820 28 3200 23 2002 1000 22 4000 25 2003 1200 20 5000 25 2004 1350 12.5 6200 24 2005 1500 11.1 7500 21 2006 1800 20 9000 20 2007 2300 30 10,800 19.7 2008 3100 32.5 12,500 15.7 2009 4200 35.5 14,500 16 Xie et al.(2012)による『Review of solar obligations in China』から