1. http://www.greentechmedia.com/articles/read/gtm-research-global-solar-pv-installations-grew-34-in-2015
2. http://resources.solarbusinesshub.com/solar-industry-reports/item/global-market-outlook-for-solar-power-2015-2019
3. http://www.pv-magazine.com/investors/module-price-index/
4. https://www.ise.fraunhofer.de/de/downloads/pdf-files/aktuelles/photovoltaics-report-in-englischer-sprache.pdf
5. Solar cell efficiency tables (version 48);Green;Prog. Photovol.Res. Appl.,2016