Telegraph (UK): Installing solar panels on the roof, which can cost up to £5,000, would take as long as 208 years to pay back the cost. However, owners of a terraced house who installed cavity wall protection would see a return on their investment in as little as three years. The sums have been calculated by the Royal Institution of Chartered Surveyors, which has published a ‘Greener Homes Price Guide’. The guide warns that many homeowners are being duped into making radical changes to their …