Hot on the heels, as it were, of recent news that the Prince of Wales has installed 32 solar photovoltaic panels on the roof of his London residence, Clarence House, comes the announcement from the Obama administration that the White House will be installing a mix of solar thermal and photovoltaic panels, spring 2011, which will generate both hot water and renewable electricity.This marks the return, after a quarter of century, of a solar thermal system not seen since the original 32 solar panels, installed by Jimmy Carter, were removed by Ronald Reagan in 1986.President Obama's strong commitment to showing belief in the future of solar energy, is being accompanied by the senate Republicans and Democrats endeavouring to push through a renewable energy standard requiring utilities to source 3% of their energy from renewables such as wind and solar power over the next two years.In the UK, over 40,000 systems have already been installed, making solar power fast becoming the leading source of alternative 'clean' energy. Solar PV systems are one of the renewable energy sources that a property can be assessed for the safe installation on a domestic household roof without?