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A simplified skyline-based method for estimating the annual solar energy potential in urban environments


Architects, engineers and urban planners have today at their disposal several tools for simulating the energy yield of photovoltaic systems. These tools are based on mathematical models that perform repetitive calculations to determine the annual irradiation received by solar panels; hence when photovoltaic systems are installed in complex urban environments, the simulations become highly computationally demanding. Here we present a simplified and yet accurate model for the direct calculation of the annual irradiation and energy yield of photovoltaic systems in urban environments. Our model is based on the correlation between the solar radiation components and the shape of the skyline profile. We show how calculations can be simplified by quantifying the skyline using two indicators: the sky view factor and the sun coverage factor. Model performance is evaluated in different climates using measured data from different photovoltaic systems. Results indicate that the proposed model significantly reduces the required computation time while preserving a high estimation accuracy.

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Fig. 1: Irradiance-based approach.
Fig. 2: Synthetic and real skyline profiles.
Fig. 3: Model fitting to an actual PV system.
Fig. 4: Model performance in sunny and cloudy climates.
Fig. 5: Model validation in the Netherlands.
Fig. 6: Model validation using four PV systems in different climates.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.


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We thank the Dutch company Solar Monkey ( for providing skyline profiles and annual AC yield measurements of PV systems monitored in the Netherlands for the validation of our model.

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Authors and Affiliations



A.C., O.I. and M.Z. conceived the research. A.C. worked on modelling and the validation analysis. H.Z. and O.I. helped with the analysis and validations. O.I. and M.Z. supervised the whole project. All authors discussed the results and contributed to the writing of the paper.

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Correspondence to Andres Calcabrini.

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The authors declare no competing interests.

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Supplementary Information

Supplementary Notes 1–2, Supplementary Figures 1–6, Supplementary Tables 1–7, Supplementary References

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Calcabrini, A., Ziar, H., Isabella, O. et al. A simplified skyline-based method for estimating the annual solar energy potential in urban environments. Nat Energy 4, 206–215 (2019).

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