Rotherham has Britain’s first street with houses powered by solar rooftiles thanks to this London company, which supplies and installs solar-energy technology. Solarcentury, founded by chairman Jeremy Leggett, raised £13.5m from investors last year and expanded its operations to France, Italy and Spain, where thermal tiles are mandatory for new buildings. High oil prices have helped to fuel sales growth of 48% a year from £6m in 2005 to £19.4m in 2008.