1. https://www.eia.gov/outlooks/aeo/pdf/aeo2019.pdf
2. https://www.irena.org
3. https://www.eurobserv-er.org/pdf/photovoltaic-barometer-2018-en/
4. Jan Kleissl, Solar Energy Forecasting and Resource Assessment (Academic Press, 2013)
5. Viorel Badescu, Modeling Solar Radiation at the Earth's Surface (Springer, Berlin, Heidelberg, 2014)