**Acknowledgements**

The total number of solar panels n that can be installed on the surface is given in Eq. (1), where Ai is the combined effective area of the facade and rooftop of the Civil Building, while S is the

The total electrical energy Q generated by solar panels installed on the Civil Building can be calculated by Eq. (2), where η is the conversion efficiency of the solar panel, w is the power output of solar panels, and Ti is the effective sunshine duration per year of each surface.

As is shown in Eq. (3), the solar panels yield more than 60 billion joules of savings in electricity, which shows that the solar panels installed on "Civil Building" reduce traditional energy consumption and in turn contribute to the overall energy efficiency. To assess economic benefit of solar panels, the payback period for solar panel cost can be calculated using Eq. (4).

In this case, p is the price of each solar panel and C is the operating cost of solar panels. Considering an average electricity price 0.88 RMB per kilowatt-hour in Nanjing, the daily sav-

Through the cost analysis, after year 11, the investment status solar panels become positive, which means that after 11.5 years, the solar panel system will operate as a positive cash flow source. Based on the 30-year estimated lifespan of the solar panels, there will be more years benefitting from the solar panel installation than years paying for it. After fully analyzing all

The switch to alternative energy sources of electricity is increasing, especially solar energy. The installation of solar panels is advertised throughout the world including China by use of information technologies. Based on the application of building energy modeling and sunlight simulation by BIM technology, and taking advantage of information modeling with 3D

ing on electricity rates P and the recovery period T can be calculated as follows.

*P* = 0.88 × (651860789.2/3600) = 159343.7485*RMB*

*T* = *C*/*P* = 1831680/159343.7485 = 11.5 *years*

the results, the investment is definitely cost-beneficial.

**5. Conclusions**

The amount of the electricity converted by solar panels can be calculated in Eq. (3).

(1)

(2)

(3)

(4)

cross-sectional area of the solar panel.

124 Emerging Solar Energy Materials

The authors' special thanks go to the National Science Council of P. R. C. for financially supporting this research (NSFC-71302138), and fund by the National Key Research and Development Program of China (2016YFC0702001-06).
