A method for evaluating both shading and power generation effects of rooftop solar PV panels for different climate zones of China
Summary (2 min read)
1. Introduction
- Due to the conventional energy shortage and environmental deterioration, the development and utilization of renewable energy have become inevitable in order to overcome the current energy crisis.
- Since PV panels are most commonly installed on building rooftop (Oliver and Jackson, 2001), numerous studies on the energy-saving performance of PV rooftop have been conducted.
- By substituting the comprehensive air temperature into the Eqs. (14) and (15), the indoor heat gain (heat loss) and heating load of the roof can be obtained, respectively.
- In order to illustrate the influence factors to the overall energy-saving efficiency, the test data were analyzed using SPSS 26.0.
3. Experimental results and model validation
- Therefore, the surface temperature at night of the PV rooftop was generally higher than that of the ordinary roof, and the effect of horizontal overhead PV roof is more obvious.
- This was mainly because the upper surface of the control body of the attached PV module received all solar radiation, just like the ordinary roof.
- 3. Heating and cooling load results 8. Compared with the ordinary roof, the heat gain caused by the short-wave solar radiation of the PV roofs was sheltered, and the heat loss caused by the PV roof’s long-wave radiation was reduced.
4. Analysis and discussions of overall energy-saving performance
- The overall energy-saving efficiency of a PV roof is affected by both outdoor air temperature and solar energy resources.
- In areas with hot summer and cold winter, the daily total heat loss and the peak heating load of the firmly-attached PV roof are higher than those of the ordinary roof.
- The overall energy-saving efficiencies of the selected cities in the winter are shown in Fig. 16.
- Also, the heat insulation of the PV modules was stronger than the shading effect.
- On the other hand, in the winter, the solar radiation on the inclined surface is higher than that on the horizontal surface, compared to the horizontally-mounted overhead PV roof, the tilted overhead PV roof obtained heat more.
5. Conclusions
- In addition, 13 typical cities in 5 climatic regions of China are selected for the investigations to evaluate the overall energy-saving performance of three PV roof types.
- The roof with a horizontal PV had the highest efficiency of 0.32.
- Among the selected regions, in the cold and severely cold regions with a large temperature diurnal range and low average temperature, the energy-saving efficiency was relatively high.
- For the tilted PV roof, this paper took 30° as the inclined angle, but the specific installation and the actual energy-saving effect should be determined after detailed analysis according to the local latitude and other conditions.
- The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Did you find this useful? Give us your feedback
Citations
35 citations
23 citations
21 citations
20 citations
References
482 citations
"A method for evaluating both shadin..." refers background in this paper
...…PV module relative to the roof surface assumed to be30° αC Absorptivity of PV battery pack 0.95 (Wang et al., 2006) εC Emissivity of PV battery pack 0.84 (Jones and Underwood, 2001) εb Emissivity of TPT backsheet 0.893 (National Standard of PR China, 2016) αr Absorptivity of the exterior surface…...
[...]
359 citations
337 citations
"A method for evaluating both shadin..." refers background in this paper
...(Palyvos, 2008); IDI denotes the intensity of roof incident scattered radiation in the absence of shading in W/m2; VF and εr denotes the view factor and the roof surface emissivity, and they are both dimensionless; Fa, Fsky and Fgr denote the radiation angle coefficient between the outer roof…...
[...]
327 citations
145 citations
"A method for evaluating both shadin..." refers methods in this paper
...Back panel temperature of PV panels denoted by Tb can be obtained from the empirical formula for the back temperature of PV modules in the Sandia electrical performance model developed by Sandia National Laboratory (Davis et al., 2001)....
[...]