1. Renewable Energy Policy Network for the 21st Century (REN21). Renewables 2011 Global Status Report, REN21, Paris; 2012.
2. Keeping the energy debate clean: how do we supply the world's energy needs?;Abbott;Proceedings of the IEEE,2010
3. International Energy Agency (IEA), 2011. IEA Guide to Reporting Energy RD&D Budget/Expenditure Statistics, IEA, France, p. 51–53.
4. AES Ltd. Solar Collectors, AES Ltd, UK. Available from: 〈http://www.aessolar.co.uk〉; 2012 [accessed 03.05.12].
5. Energy Saving Trust (EST) UK, 2011. Here Comes the Sun: A Field Trial of Solar Water Heating Systems, EST, UK, p. 1–23.