1. Beltram, H., Swierczynski, M., Luna, A., Vazquez, G., Belenguer, E., 2011. Photovoltaic plants generation improvement using Li-ion batteries as energy buffer. In: 2011 IEEE International Symposium Industrial Electronics (ISIE), Gdansk, Poland, pp. 2063–2069.
2. Bito, A., 2005. Overview of the sodium–sulfur (NAS) battery for the IEEE stationary battery committee. In: 2005 IEEE Power Engineering Society General Meeting, vol. 2. San Francisco, CA, pp. 1232–1235
3. EER, 2012. European Energy Exchange. 〈http://www.eex.com/de/〉(accessed 22.06.2012).
4. EPIA, 2011. Annual Report 2011. European Photovoltaic Industry Association, Brussels, Belgium, 2012, Available: 〈http://www.epia.org/index.php?eID=tx_nawsecuredl&u=0&file=fileadmin/EPIA_docs/publications/epia/Annual_Report_2011.pdf&t=1348692622&hash=283bd8714d40e172541457f047e83049〉.
5. EREC, 2008. Renewable Energy Technology Roadmap 20% by 2020. European Renewable Energy Council, Brussels, Belgium, 2008, Available: 〈http://www.erec.org/fileadmin/erec_docs/Documents/Publications/Renewable_Energy_Technology_Roadmap.pdf〉.