1. Alternative Energy: Solar Energy. http://www.altenergy.org/renewables/solar.html . Accessed 3 July 2013.
2. U.S. Energy Information Administration: Electric Power Monthly with Data for February 2013, U.S. Energy Information Administration, Washington, DC, 2013.
3. Solarbuzz: Solar Electricity Prices (2012 March). http://www.solarbuzz.com/facts-and-figures/retail-price-environment/solar-electricity-prices . Accessed 3 July 2013.
4. PV Insight: Solar PV Cell Weekly Spot Price-PVinsights (June 30, 2013). http://pvinsights.com/index.php . Accessed 3 July 2013.
5. Green Rhino Energy: PV Cells & Modules. http://www.greenrhinoenergy.com/solar/technologies/pv_modules.php . Accessed 3 July 2013.