Chinese solar greenhouses (CSG) play an important role in the development of horticultural facilities in China. They are widely used to grow vegetables during winter without any auxiliary heating, especially when the monthly daily average air temperature in the coldest three months of the year was below −10 °C , .
A promising prospect is shown by China's modern solar greenhouses at present levels of performances and costs exemplified by the photovoltaic (PV) greenhouses with a practicable payback period of less than 9 years.
3.2. Economic evaluation The economic evaluation including the cost, operating income and the payback time of the combined agriculture and solar system sectors is conducted to assess the potential of the application of modern solar greenhouses in China.
The Beijing Solar Heating Greenhouse Project is a demonstration project including 12 pilot modern greenhouses with coverage of 520 m 2 solar collectors . Through the solar heating system, the average temperature can be increased by 4–5 ℃.
Schematic diagram of Chinese solar greenhouse with air channel heat exchange. Air channel in the north wall (A, B), air channel underground (C, D). In CSGs, the north wall can not only bear loadings, but also absorb solar energy during the day and release heat into CSG during the night. A traditional CSG has a relatively thick north wall.
Conclusion Modern solar greenhouse is an important initiative in China's protected cultivation history for it benefits in energy saving, pollution reduction, and comprehensive competitiveness of modern agriculture improvement, especially in this low carbon production era.